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Su YL, Dong K, Zheng H, Doyle MP. Generation of Diazomethyl Radicals by Hydrogen Atom Abstraction and Their Cycloaddition with Alkenes. Angew Chem Int Ed Engl 2021; 60:18484-18488. [PMID: 34043866 DOI: 10.1002/anie.202105472] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 05/23/2021] [Indexed: 12/16/2022]
Abstract
A general catalytic methodology for the synthesis of pyrazolines from α-diazo compounds and conjugated alkenes is reported. The direct hydrogen atom transfer (HAT) process of α-diazo compounds promoted by the tert-butylperoxy radical generates electrophilic diazomethyl radicals, thereby reversing the reactivity of the carbon atom attached with the diazo group. The regiocontrolled addition of diazomethyl radicals to carbon-carbon double bonds followed by intramolecular ring closure on the terminal diazo nitrogen and tautomerization affords a diverse set of pyrazolines in good yields with excellent regioselectivity. This strategy overcomes the limitations of electron-deficient alkenes in traditional dipolar [3+2]-cycloaddition of α-diazo compounds with alkenes. Furthermore, the straightforward formation of the diazomethyl radicals provides umpolung reactivity, thus opening new opportunities for the versatile transformations of diazo compounds.
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Affiliation(s)
- Yong-Liang Su
- Department of Chemistry, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA
| | - Kuiyong Dong
- Department of Chemistry, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA
| | - Haifeng Zheng
- Department of Chemistry, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA
| | - Michael P Doyle
- Department of Chemistry, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA
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102
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Lamhauge JN, Corti V, Liu Y, Jørgensen KA. Enantioselective α-Etherification of Branched Aldehydes via an Oxidative Umpolung Strategy. Angew Chem Int Ed Engl 2021; 60:18728-18733. [PMID: 34087048 DOI: 10.1002/anie.202105721] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Indexed: 11/05/2022]
Abstract
Saturated carbonyl compounds are, via their enolate analogues, inherently nucleophilic at the α-position. In the presence of a benzoquinone oxidant, the polarity of the α-position of racemic α-branched aldehydes is inverted, allowing for an enantioselective etherification using readily available oxygen-based nucleophiles and an amino acid-derived primary amine catalyst. A survey of benzoquinone oxidants identified p-fluoranil and DDQ as suitable reaction partners. p-Fluoranil enables the preparation of α-aryloxylated aldehydes using phenol nucleophiles in up to 91 % ee, following either a one-step or a two-step, one-pot protocol. DDQ allows for a more general etherification protocol in combination with a broader range of alcohol nucleophiles with enantioselectivities up to 95 % ee. Control experiments and isolation of a key quinol intermediate supports a mechanism proceeding via an SN 2 dynamic-kinetic resolution. These studies provide the basis for an aminocatalytic umpolung concept that allows for the asymmetric construction of tertiary ethers in the α-position of aldehydes.
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Affiliation(s)
- Johannes N Lamhauge
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Vasco Corti
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Yidong Liu
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
| | - Karl Anker Jørgensen
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark
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103
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Wang S, König B. Catalytic Generation of Carbanions through Carbonyl Umpolung. Angew Chem Int Ed Engl 2021; 60:21624-21634. [PMID: 33991000 PMCID: PMC8518712 DOI: 10.1002/anie.202105469] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Indexed: 12/16/2022]
Abstract
Carbonyl Umpolung is a powerful strategy in organic chemistry to construct complex molecules. Over the last few years, versatile catalytic approaches for the generation of acyl anion equivalents from carbonyl compounds have been developed, but methods to obtain alkyl carbanions from carbonyl compounds in a catalytic fashion are still at an early stage. This Minireview summarizes recent progress in the generation of alkyl carbanions through catalytic carbonyl Umpolung. Two different catalytic approaches can be utilized to enable the generation of alkyl carbanions from carbonyl compounds: the catalytic Wolff–Kishner reaction and the catalytic single‐electron reduction of carbonyl compounds and imines. We discuss the reaction scope, mechanistic insights, and synthetic applications of the methods as well as potential future developments.
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Affiliation(s)
- Shun Wang
- Faculty of Chemistry and Pharmacy University of Regensburg Universitaetsstrasse 31 93053 Regensburg Germany
| | - Burkhard König
- Faculty of Chemistry and Pharmacy University of Regensburg Universitaetsstrasse 31 93053 Regensburg Germany
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104
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Jiao J, Wang X. Merging Electron Transfer with 1,2‐Metalate Rearrangement: Deoxygenative Arylation of Aromatic Amides with Arylboronic Esters. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202104359] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Jiwen Jiao
- State Key Laboratory of Organometallic Chemistry Center for Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Xiaoming Wang
- State Key Laboratory of Organometallic Chemistry Center for Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
- School of Chemistry and Materials Science Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences 1 Sub-lane Xiangshan Hangzhou 310024 China
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105
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Visible-light photoredox-catalyzed umpolung carboxylation of carbonyl compounds with CO 2. Nat Commun 2021; 12:3306. [PMID: 34083530 PMCID: PMC8175691 DOI: 10.1038/s41467-021-23447-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/29/2021] [Indexed: 12/19/2022] Open
Abstract
Photoredox-mediated umpolung strategy provides an alternative pattern for functionalization of carbonyl compounds. However, general approaches towards carboxylation of carbonyl compounds with CO2 remain scarce. Herein, we report a strategy for visible-light photoredox-catalyzed umpolung carboxylation of diverse carbonyl compounds with CO2 by using Lewis acidic chlorosilanes as activating/protecting groups. This strategy is general and practical to generate valuable α-hydroxycarboxylic acids. It works well for challenging alkyl aryl ketones and aryl aldehydes, as well as for α-ketoamides and α-ketoesters, the latter two of which have never been successfully applied in umpolung carboxylations with CO2 (to the best of our knowledge). This reaction features high selectivity, broad substrate scope, good functional group tolerance, mild reaction conditions and facile derivations of products to bioactive compounds, including oxypheonium, mepenzolate bromide, benactyzine, and tiotropium. Moreover, the formation of carbon radicals and carbanions as well as the key role of chlorosilanes are supported by control experiments. Compounds bearing a carbonyl group, such as aldehydes and ketones, are important industrial chemicals and widespread in pharmaceuticals and natural products. Here, the authors report a strategy for visible-light photoredox-catalyzed umpolung carboxylation of diverse carbonyl compounds with CO2, to generate valuable α-hydroxycarboxylic acids.
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106
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Wan LQ, Cao JG, Niu D, Zhang X. Cobalt-Catalyzed Umpolung Alkylation of Imines To Generate α-Branched Aliphatic Amines. Org Lett 2021; 23:3818-3822. [PMID: 33974795 DOI: 10.1021/acs.orglett.1c00835] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Here we report a general and mild approach to prepare α-branched aliphatic amines from imines. This method capitalizes on a cobalt-catalyzed umpolung alkylation of imines, employs easily available reaction partners, and demonstrates a broad substrate scope. Mechanistic studies suggest this transformation occurs by a radical pathway.
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Affiliation(s)
- Li-Qiang Wan
- Department of Emergency, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and School of Chemical Engineering, Sichuan University, Chengdu, 610041, China
| | - Jin-Ge Cao
- Department of Emergency, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and School of Chemical Engineering, Sichuan University, Chengdu, 610041, China
| | - Dawen Niu
- Department of Emergency, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and School of Chemical Engineering, Sichuan University, Chengdu, 610041, China
| | - Xia Zhang
- Department of Emergency, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and School of Chemical Engineering, Sichuan University, Chengdu, 610041, China
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107
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Hussain Y, Chauhan P. Catalytic asymmetric umpolung reactions of imines via 2-azaallyl anion intermediates. Org Biomol Chem 2021; 19:4193-4212. [PMID: 33870977 DOI: 10.1039/d1ob00409c] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The imine umpolung is a relatively new and interesting strategy, especially in catalytic asymmetric synthesis. A significant development in organo- and transition metal-catalyzed umpolung of imines took place only in the recently concluded decade. A majority of the reports on the asymmetric umpolung of imines involve the initial generation of 2-azaallyl anion intermediates with the chiral catalysts, which serve as a significant driving force for the umpolung addition/substitution reactions. A variety of organocatalysts such as bifunctional cinchona alkaloids including squaramides and thioureas, chiral BINOL derived phosphoric acids, phase transfer catalysts (PTCs), phosphines, and transition metal-complexes of iridium, copper and palladium have been employed to achieve the excellent level of asymmetric induction in such types of umpolung reactions. The asymmetric imine umpolung strategy has been applied successfully to synthesize synthetic amino-acid derivatives and other useful chiral amines, including drugs and potentially bioactive molecules. This review summarizes all the significant recent development in catalytic umpolung reactions of imines involving a 2-azaallyl anion intermediate.
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Affiliation(s)
- Yaseen Hussain
- Department of Chemistry, Indian Institute of Technology Jammu Jagti, NH 44, Nagrota Bypass, Jammu, J&K 181221, India.
| | - Pankaj Chauhan
- Department of Chemistry, Indian Institute of Technology Jammu Jagti, NH 44, Nagrota Bypass, Jammu, J&K 181221, India.
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108
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Pareek M, Reddi Y, Sunoj RB. Tale of the Breslow intermediate, a central player in N-heterocyclic carbene organocatalysis: then and now. Chem Sci 2021; 12:7973-7992. [PMID: 34194690 PMCID: PMC8208132 DOI: 10.1039/d1sc01910d] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 04/28/2021] [Indexed: 12/27/2022] Open
Abstract
N-Heterocyclic carbenes (NHCs) belong to the popular family of organocatalysts used in a wide range of reactions, including that for the synthesis of complex natural products and biologically active compounds. In their organocatalytic manifestation, NHCs are known to impart umpolung reactivity to aldehydes and ketones, which are then exploited in the generation of homoenolate, acyl anion, and enolate equivalents suitable for a plethora of reactions such as annulation, benzoin, Stetter, Claisen rearrangement, cycloaddition, and C-C and C-H bond functionalization reactions and so on. A common thread that runs through these NHC catalyzed reactions is the proposed involvement of an enaminol, also known as the Breslow intermediate, formed by the nucleophilic addition of an NHC to a carbonyl group of a suitable electrophile. In the emerging years of NHC catalysis, enaminol remained elusive and was largely considered a putative intermediate owing to the difficulties encountered in its isolation and characterization. However, in the last decade, synergistic efforts utilizing an array of computational and experimental techniques have helped in gaining important insights into the formation and characterization of Breslow intermediates. Computational studies have suggested that a direct 1,2-proton transfer within the initial zwitterionic intermediate, generated by the action of an NHC on the carbonyl carbon, is energetically prohibitive and hence the participation of other species capable of promoting an assisted proton transfer is more likely. The proton transfer assisted by additives (such as acids, bases, other species, or even a solvent) was found to ease the kinetics of formation of Breslow intermediates. These important details on the formation, in situ detection, isolation, and characterization of the Breslow intermediate are scattered over a series of reports spanning well over a decade, and we intend to consolidate them in this review and provide a critical assessment of these developments. Given the central role of the Breslow intermediate in organocatalytic reactions, this treatise is expected to serve as a valuable source of knowledge on the same.
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Affiliation(s)
- Monika Pareek
- Department of Chemistry, Indian Institute of Technology Bombay Powai Mumbai 400076 India
| | - Yernaidu Reddi
- Department of Chemistry, Indian Institute of Technology Bombay Powai Mumbai 400076 India
| | - Raghavan B Sunoj
- Department of Chemistry, Indian Institute of Technology Bombay Powai Mumbai 400076 India
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109
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Gaykar RN, George M, Guin A, Bhattacharjee S, Biju AT. An Umpolung Oxa-[2,3] Sigmatropic Rearrangement Employing Arynes for the Synthesis of Functionalized Enol Ethers. Org Lett 2021; 23:3447-3452. [PMID: 33830779 DOI: 10.1021/acs.orglett.1c00911] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An oxa-[2,3] sigmatropic rearrangement involving arynes is reported featuring the umpolung of ketones, where the C═O bond polarity is reversed. The in situ-generated sulfur ylides from β-keto thioethers and arynes undergo efficient rearrangement allowing the facile and robust synthesis of functionalized enol ethers in high yields and excellent functional group compatibility. Preliminary mechanistic studies rule out the possibility of Pummerer-type rearrangement operating in this case.
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Affiliation(s)
- Rahul N Gaykar
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Malini George
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Avishek Guin
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Subrata Bhattacharjee
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Akkattu T Biju
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
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110
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Trofimova A, Holownia A, Tien CH, Širvinskas MJ, Yudin AK. Acylboronates in Polarity-Reversed Generation of Acyl Palladium(II) Intermediates. Org Lett 2021; 23:3294-3299. [PMID: 33848176 DOI: 10.1021/acs.orglett.1c00742] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We report a catalytic cross-coupling process between aryl (pseudo)halides and boron-based acyl anion equivalents. This mode of acylboronate reactivity represents polarity reversal, which is supported by the observation of tetracoordinated boronate and acyl palladium(II) species by 11B, 31P NMR, and mass spectrometry. A broad scope of aliphatic and aromatic acylboronates has been examined, as well as a variety of aryl (pseudo)halides.
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Affiliation(s)
- Alina Trofimova
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Aleksandra Holownia
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Chieh-Hung Tien
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Martynas J Širvinskas
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Andrei K Yudin
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
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111
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Feng Q, Huang H, Sun J. Ru-Catalyzed [3 + 2] Cycloaddition of Nitrile Oxides and Electron-Rich Alkynes with Reversed Regioselectivity. Org Lett 2021; 23:2431-2436. [PMID: 33750136 DOI: 10.1021/acs.orglett.1c00273] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Polarity reversal ("umpolung") of a functional group can override its inherent reactivity and lead to distinct bond-forming modes. Herein we describe a rarely studied cycloaddition between nitrile oxides and electron-rich alkynes with reversed regioselectivity, leading to the useful 4-heterosubstituted isoxazoles. The use of a ruthenium catalyst completely overrides the inherent polarity of nitrile oxides. This reversed regioselectivity was also observed for their reactions with a range of electron-deficient alkynes.
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Affiliation(s)
- Qiang Feng
- Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China.,Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Hai Huang
- Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China
| | - Jianwei Sun
- Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China.,Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
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112
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Barman D, Ghosh T, Show K, Debnath S, Ghosh T, Maiti DK. NHC-Mediated Stetter-Aldol and Imino-Stetter-Aldol Domino Cyclization to Naphthalen-1(2 H)-ones and Isoquinolines. Org Lett 2021; 23:2178-2182. [PMID: 33661653 DOI: 10.1021/acs.orglett.1c00337] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
N-Heterocyclic carbene-catalyzed tandem Stetter-aldol reaction of phthalaldehyde and α,β-unsaturated ketimines has been developed to afford functionalized naphthalen-1(2H)-one derivatives as the formal [4+2] annulation product. Interestingly, the reaction of aldimines led to the formation of isoquinoline derivatives instead of the expected indanone derivatives as a [4+1] annulation product.
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Affiliation(s)
- Debabrata Barman
- Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, India
| | - Tanmoy Ghosh
- Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, India
| | - Krishanu Show
- Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, India
| | - Sudipto Debnath
- Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, India
| | - Tapas Ghosh
- Department of Applied Science, Maulana Abul Kalam Azad University of Technology, Haringhata 741249, West Bengal, India
| | - Dilip K Maiti
- Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700009, India
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113
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Dibrell SE, Tao Y, Reisman SE. Synthesis of Complex Diterpenes: Strategies Guided by Oxidation Pattern Analysis. Acc Chem Res 2021; 54:1360-1373. [PMID: 33621061 DOI: 10.1021/acs.accounts.0c00858] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
With complex molecular architectures, intriguing oxidation patterns, and wide-ranging biological activities, diterpene natural products have greatly impacted research in organic chemistry and drug discovery. Our laboratory has completed total syntheses of several highly oxidized diterpenes, including the ent-kauranoids maoecrystal Z, trichorabdal A, and longikaurin E; the antibiotic pleuromutilin; and the insecticides ryanodol, ryanodine, and perseanol. In this Account, we show how analysis of oxidation patterns and inherent functional group relationships can inform key C-C bond disconnections that greatly simplify the complexity of polycyclic structures and streamline their total syntheses. In articulating these concepts, we draw heavily from the approaches to synthetic strategy that were codified by Evans, Corey, Seebach, and others, based on the formalism that heteroatoms impose an alternating acceptor and donor reactivity pattern upon a carbon skeleton. We find these ideas particularly useful when considering oxidized diterpenes as synthetic targets.In the first part of the Account, we describe the use of reductive cyclizations as strategic tactics for building polycyclic systems with γ-hydroxyketone motifs. We have leveraged Sm-ketyl radical cyclizations as "reactivity umpolungs" to generate γ-hydroxyketones in our total syntheses of the Isodon ent-kauranoid diterpenes (-)-maoecrystal Z, (-)-longikaurin E, and (-)-trichorabdal A. Following this work, we identified the same γ-hydroxyketone pattern in the diterpene antibiotic (+)-pleuromutilin, which again inspired the use of a SmI2-mediated reductive cyclization, this time to construct a bridging eight-membered ring. This collection of four total syntheses highlights how reductive cyclizations are particularly effective umpolung tactics when used to simultaneously form rings and introduce 1,4-dioxygenation patterns.In the second part of the Account, we detail the syntheses of the complex and highly oxidized ryanodane and isoryanodane diterpenes and present the oxidation pattern analysis that guided our synthetic designs. We first discuss our 15-step total synthesis of (+)-ryanodol, which incorporated five of the eight oxygen atoms in just two transformations: a dihydroxylation of (S)-pulegone and a SeO2-mediated trioxidation of the A-ring cyclopentenone. This latter transformation gave rise to an independent investigation of SeO2-mediated peroxidations of simple bicyclic cyclopent-2-en-1-ones. The syntheses of (+)-ryanodine and (+)-20-deoxyspiganthine are also presented, which required modified end-game strategies to selectively incorporate the key pyrrole-2-carboxylate ester. Finally, we describe our fragment coupling approach to prepare the isoryanodane diterpene (+)-perseanol. Using a similar oxidation pattern analysis to that developed in the synthesis of ryanodol, we again identified a two-stage strategy to install the five hydroxyl groups. This strategy was enabled by a Pd-mediated carbopalladation/carbonylation cascade and leveraged unexpected, emergent reactivity to sequence a series of late-stage oxidations.While each of the diterpene natural products discussed in this Account present unique synthetic questions, we hope that through their collective discussion, we provide a conceptual framework that condenses and summarizes the chemical knowledge we have learned and inspires future discourse and innovations in strategy design and methodology development.
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Affiliation(s)
- Sara E. Dibrell
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Yujia Tao
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Sarah E. Reisman
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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114
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Park E, Park J, Cheon C. Remarkable Differences in Reactivity between Cyanide and N‐Heterocyclic Carbene
s
in
Ring‐Closing
Reactions of 4‐(
2‐Formylphenoxy
)but‐2‐Enoate Derivatives. B KOREAN CHEM SOC 2021. [DOI: 10.1002/bkcs.12146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Eunjoon Park
- Department of Chemistry Korea University Seoul 02841 Korea
| | - Jina Park
- Department of Chemistry Korea University Seoul 02841 Korea
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115
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Zhu D, Qu Z, Zhou J, Stephan DW. The Reactivity of Isomeric Nitrenium Lewis Acids with Phosphines, Carbenes, and Phosphide. Chemistry 2021; 27:2861-2867. [PMID: 33137240 PMCID: PMC7898612 DOI: 10.1002/chem.202004798] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Indexed: 11/25/2022]
Abstract
Alkylation of spiro[fluorene-9,3'-indazole] at N(1) and N(2) with tBuCl affords the nitrenium cations [C6 H4 N2 (tBu)C(C12 H8 )][BF4 ], 1 and 2, respectively. Compound 1 converts to 2 over the temperature range 303-323 K with a free energy barrier of 28±5 kcal mol-1 . Reaction of 1 with PMe3 afforded the N-bound phosphine adduct [C6 H4 N(tBu)N(PMe3 )C(C12 H8 )]BF4 ] 3. However, phosphines attack 2 at the para-carbon atom of the aryl group with concurrent cleavage of N(2)-C(1) bond and proton migration to C(1) affording [(R3 P)C6 H3 NN(tBu)CH(C12 H8 )][BF4 ] (R=Me 4, nBu 5). Analogous reactions of 1 and 2 with the carbene SIMes prompt attack at the para-carbon with concurrent loss of H. affording the radical cation salts [(SIMes)C6 H3 N(tBu)NC(C12 H8 ). ][BF4 ] 6 and [(SIMes)C6 H3 NN(tBu)C(C12 H8 ). ][BF4 ] 7, whereas reaction of 2 with BAC gives the Lewis acid-base adduct, [C6 H4 N(BAC)N(tBu)C(C12 H8 )][BF4 ] 8. Finally, reactions of 1 and 2 with KPPh2 result in electron transfer affording (PPh2 )2 and the persistent radicals C6 H4 N(tBu)NC(C12 H8 ). and C6 H4 NN(tBu)C(C12 H8 ). . The detailed reaction mechanisms are also explored by extensive DFT calculations.
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Affiliation(s)
- Diya Zhu
- Department of ChemistryUniversity of Toronto80 St George StTorontoOntarioM5S3H6Canada
| | - Zheng‐Wang Qu
- Mulliken Center for Theoretical ChemistryInstitut für Physikalische und Theoretische ChemieRheinische Friedrich-Wilhelms-Universität BonnBeringstrasse 453115BonnGermany
| | - Jiliang Zhou
- Department of ChemistryUniversity of Toronto80 St George StTorontoOntarioM5S3H6Canada
| | - Douglas W. Stephan
- Department of ChemistryUniversity of Toronto80 St George StTorontoOntarioM5S3H6Canada
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116
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Mou ZD, Zhang X, Niu D. Catalytic asymmetric umpolung reaction of imines to synthesize isoindolinones and tetrahydroisoquinolines. GREEN SYNTHESIS AND CATALYSIS 2021. [DOI: 10.1016/j.gresc.2021.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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117
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Kanai M, Beller M. Introduction to hybrid catalysis. Org Biomol Chem 2021; 19:702-704. [PMID: 33491700 DOI: 10.1039/d0ob90177f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Motomu Kanai and Matthias Beller introduce the Organic & Biomolecular Chemistry themed issue on hybrid catalysis.
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Affiliation(s)
- Motomu Kanai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Matthias Beller
- Leibniz-Institut für Katalyse e.V., Albert-Einstein Straße 29a, Rostock, 18059, Germany.
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118
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Bauer A, Maulide N. Recent discoveries on the structure of iodine(iii) reagents and their use in cross-nucleophile coupling. Chem Sci 2021; 12:853-864. [PMID: 34163852 PMCID: PMC8178994 DOI: 10.1039/d0sc03266b] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
This perspective article discusses structural features of iodine(iii) compounds as a prelude to presenting their use as umpolung reagents, in particular as pertains to their ability to promote the selective coupling of two nucleophilic species via 2e- oxidation.
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Affiliation(s)
- Adriano Bauer
- Institute of Organic Chemistry, University of Vienna Währinger Strasse 38 1090 Vienna Austria http://maulide.univie.ac.at
| | - Nuno Maulide
- Institute of Organic Chemistry, University of Vienna Währinger Strasse 38 1090 Vienna Austria http://maulide.univie.ac.at
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119
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Yoshida Y, Kukita M, Omori K, Mino T, Sakamoto M. Iminophosphorane-mediated regioselective umpolung alkylation reaction of α-iminoesters. Org Biomol Chem 2021; 19:4551-4564. [DOI: 10.1039/d1ob00596k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first regioselective umpolung alkylation of α-iminoesters with alkyl halides mediated by iminophosphorane has developed (up to 82% yield).
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Affiliation(s)
- Yasushi Yoshida
- Molecular Chirality Research Center
- Graduate School of Engineering
- Chiba University
- Chiba 263-8522
- Japan
| | - Mayu Kukita
- Molecular Chirality Research Center
- Graduate School of Engineering
- Chiba University
- Chiba 263-8522
- Japan
| | - Kazuki Omori
- Molecular Chirality Research Center
- Graduate School of Engineering
- Chiba University
- Chiba 263-8522
- Japan
| | - Takashi Mino
- Molecular Chirality Research Center
- Graduate School of Engineering
- Chiba University
- Chiba 263-8522
- Japan
| | - Masami Sakamoto
- Molecular Chirality Research Center
- Graduate School of Engineering
- Chiba University
- Chiba 263-8522
- Japan
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120
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121
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Abstract
Carbon dioxide is an intrinsically stable molecule; however, it can readily react with various nucleophilic reagents. In the presence of a cyanide source, CO2 was proven to be useful to promote addition reactions. Here we report the use of CO2 to facilitate 1,4-conjugate cyanide addition reaction to chalcones to generate organonitriles. Nitriles are key component in organic synthesis due to their utility in numerous functional group transformation, however, conjugation addition of cyanide has been a challenge in this substrate class due to side reactions. To mitigate this, we employed simple ammonium and metal cyanide sources as nucleophiles under carbon dioxide atmosphere where high selectivity toward the desired product was obtained. The presented reaction is not feasible under inert atmosphere, which highlights the important role of CO2, as a Lewis and Brøndsted acidic catalyst. Further derivatization of organonitriles compounds were performed to showcase the utility of the reaction, while an unprecedented dimerization reaction was identified and characterized, affording a cyclopentanone scaffold.
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122
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Salvitti C, Chiarotto I, Pepi F, Troiani A. Charge-Tagged N-Heterocyclic Carbenes (NHCs): Revealing the Hidden Side of NHC-Catalysed Reactions through Electrospray Ionization Mass Spectrometry. Chempluschem 2020; 86:209-223. [PMID: 33252194 DOI: 10.1002/cplu.202000656] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/16/2020] [Indexed: 01/08/2023]
Abstract
N-heterocyclic carbenes (NHCs) are key intermediates in a variety of chemical reactions. Owing to their transient nature, the interception and characterization of these reactive species have always been challenging. Similarly, the study of reaction mechanisms in which carbenes act as catalysts is still an active research field. This Minireview describes the contribution of electrospray ionization mass spectrometry (ESI-MS) to the detection of charge-tagged NHCs resulting from the insertion of an ionic group into the molecular scaffold. The use of different mass spectrometric techniques, combined with the charge-tagging strategy, allowed clarification of the involvement of NHCs in archetypal reactions and the study of their intrinsic chemistry.
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Affiliation(s)
- Chiara Salvitti
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, Rome, Italy
| | - Isabella Chiarotto
- Dipartimento di Scienze di Base e Applicate per l'Ingegneria, Sapienza Università di Roma, Via Castro Laurenziano 7, Rome, Italy
| | - Federico Pepi
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, Rome, Italy
| | - Anna Troiani
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, Rome, Italy
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123
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Kim UB, Jung DJ, Jeon HJ, Rathwell K, Lee SG. Synergistic Dual Transition Metal Catalysis. Chem Rev 2020; 120:13382-13433. [DOI: 10.1021/acs.chemrev.0c00245] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- U Bin Kim
- Department of Chemistry and Nanoscience (BK 21 Plus), Ewha Womans University, Seoul 120-750, Korea
| | - Da Jung Jung
- Department of Chemistry and Nanoscience (BK 21 Plus), Ewha Womans University, Seoul 120-750, Korea
| | - Hyun Ji Jeon
- Department of Chemistry and Nanoscience (BK 21 Plus), Ewha Womans University, Seoul 120-750, Korea
| | - Kris Rathwell
- Department of Chemistry and Nanoscience (BK 21 Plus), Ewha Womans University, Seoul 120-750, Korea
| | - Sang-gi Lee
- Department of Chemistry and Nanoscience (BK 21 Plus), Ewha Womans University, Seoul 120-750, Korea
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124
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Kiefl GM, Gulder T. α-Functionalization of Ketones via a Nitrogen Directed Oxidative Umpolung. J Am Chem Soc 2020; 142:20577-20582. [DOI: 10.1021/jacs.0c10700] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Gabriel M. Kiefl
- Department of Chemistry, Technical University Munich, Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Tanja Gulder
- Department of Chemistry, Technical University Munich, Lichtenbergstrasse 4, 85748 Garching, Germany
- Institute of Organic Chemistry, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
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125
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Tan H, Wang S, Yan Z, Liu J, Wei J, Song S, Jiao N. N‐Heterocyclic Carbene Catalyzed Ester Synthesis from Organic Halides through Incorporation of Oxygen Atoms from Air. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202011039] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Hui Tan
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Shen‐An Wang
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Zixi Yan
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Jianzhong Liu
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Jialiang Wei
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Song Song
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Ning Jiao
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
- State Key Laboratory of Organometallic Chemistry Chinese Academy of Sciences Shanghai 200032 China
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126
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Tan H, Wang S, Yan Z, Liu J, Wei J, Song S, Jiao N. N‐Heterocyclic Carbene Catalyzed Ester Synthesis from Organic Halides through Incorporation of Oxygen Atoms from Air. Angew Chem Int Ed Engl 2020; 60:2140-2144. [DOI: 10.1002/anie.202011039] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 09/23/2020] [Indexed: 11/09/2022]
Affiliation(s)
- Hui Tan
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Shen‐An Wang
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Zixi Yan
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Jianzhong Liu
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Jialiang Wei
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Song Song
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
| | - Ning Jiao
- State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University Xue Yuan Rd. 38 Beijing 100191 China
- State Key Laboratory of Organometallic Chemistry Chinese Academy of Sciences Shanghai 200032 China
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127
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Onyeagusi CI, Malcolmson SJ. Strategies for the Catalytic Enantioselective Synthesis of α-Trifluoromethyl Amines. ACS Catal 2020; 10:12507-12536. [PMID: 34306806 PMCID: PMC8302206 DOI: 10.1021/acscatal.0c03569] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The exploitation of the α-trifluoromethylamino group as an amide surrogate in peptidomimetics and drug candidates has been on the rise. In a large number of these cases, this moiety bears stereochemistry with the stereochemical identity having important consequences on numerous molecular properties, such as the potency of the compound. Yet, the majority of stereoselective syntheses of α-CF3 amines rely on diastereoselective couplings with chiral reagents. Concurrent with the rapid expansion of fluorine into pharmaceuticals has been the development of catalytic enantioselective means of preparing α-trifluoromethyl amines. In this work, we outline the strategies that have been employed for accessing these enantioenriched amines, including normal polarity approaches and several recent developments in imine umpolung transformations.
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Affiliation(s)
- Chibueze I Onyeagusi
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Steven J Malcolmson
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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128
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Kleemiss F, Justies A, Duvinage D, Watermann P, Ehrke E, Sugimoto K, Fugel M, Malaspina LA, Dittmer A, Kleemiss T, Puylaert P, King NR, Staubitz A, Tzschentke TM, Dringen R, Grabowsky S, Beckmann J. Sila-Ibuprofen. J Med Chem 2020; 63:12614-12622. [PMID: 32931274 DOI: 10.1021/acs.jmedchem.0c00813] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The synthesis, characterization, biological activity, and toxicology of sila-ibuprofen, a silicon derivative of the most common nonsteroidal anti-inflammatory drug, is reported. The key improvements compared with ibuprofen are a four times higher solubility in physiological media and a lower melting enthalpy, which are attributed to the carbon-silicon switch. The improved solubility is of interest for postsurgical intravenous administration. A potential for pain relief is rationalized via inhibition experiments of cyclooxygenases I and II (COX-I and COX-II) as well as via a set of newly developed methods that combine molecular dynamics, quantum chemistry, and quantum crystallography. The binding affinity of sila-ibuprofen to COX-I and COX-II is quantified in terms of London dispersion and electrostatic interactions in the active receptor site. This study not only shows the potential of sila-ibuprofen for medicinal application but also improves our understanding of the mechanism of action of the inhibition process.
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Affiliation(s)
- Florian Kleemiss
- University of Bremen, Institute for Inorganic Chemistry and Crystallography, Leobener Str. 3 and 7, 28359 Bremen, Germany.,University of Bern, Department of Chemistry and Biochemistry, Freiestrasse 3, 3012 Bern, Switzerland
| | - Aileen Justies
- Free University of Berlin, Institute of Chemistry and Biochemistry, Fabeckstr. 34-36, 14195 Berlin, Germany
| | - Daniel Duvinage
- University of Bremen, Institute for Inorganic Chemistry and Crystallography, Leobener Str. 3 and 7, 28359 Bremen, Germany
| | - Patrick Watermann
- University of Bremen, Center for Biomolecular Interactions Bremen and Center for Environmental Research and Sustainable Technology, Leobener Str. 5, 28359 Bremen, Germany
| | - Eric Ehrke
- University of Bremen, Center for Biomolecular Interactions Bremen and Center for Environmental Research and Sustainable Technology, Leobener Str. 5, 28359 Bremen, Germany
| | - Kunihisa Sugimoto
- Japan Synchrotron Radiation Research Institute (JASRI), Diffraction & Scattering Division, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan.,Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Yoshida-Ushinomiya-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Malte Fugel
- University of Bremen, Institute for Inorganic Chemistry and Crystallography, Leobener Str. 3 and 7, 28359 Bremen, Germany
| | - Lorraine A Malaspina
- University of Bremen, Institute for Inorganic Chemistry and Crystallography, Leobener Str. 3 and 7, 28359 Bremen, Germany.,University of Bern, Department of Chemistry and Biochemistry, Freiestrasse 3, 3012 Bern, Switzerland
| | - Anneke Dittmer
- University of Bremen, Institute for Inorganic Chemistry and Crystallography, Leobener Str. 3 and 7, 28359 Bremen, Germany
| | - Torsten Kleemiss
- University of Bremen, Institute for Inorganic Chemistry and Crystallography, Leobener Str. 3 and 7, 28359 Bremen, Germany
| | - Pim Puylaert
- University of Bremen, Institute for Inorganic Chemistry and Crystallography, Leobener Str. 3 and 7, 28359 Bremen, Germany
| | - Nelly R King
- Free University of Berlin, Institute of Chemistry and Biochemistry, Fabeckstr. 34-36, 14195 Berlin, Germany
| | - Anne Staubitz
- University of Bremen, Institute for Analytical and Organic Chemistry, Leobener Str. 7, 28359 Bremen, Germany
| | | | - Ralf Dringen
- University of Bremen, Center for Biomolecular Interactions Bremen and Center for Environmental Research and Sustainable Technology, Leobener Str. 5, 28359 Bremen, Germany
| | - Simon Grabowsky
- University of Bremen, Institute for Inorganic Chemistry and Crystallography, Leobener Str. 3 and 7, 28359 Bremen, Germany.,University of Bern, Department of Chemistry and Biochemistry, Freiestrasse 3, 3012 Bern, Switzerland
| | - Jens Beckmann
- University of Bremen, Institute for Inorganic Chemistry and Crystallography, Leobener Str. 3 and 7, 28359 Bremen, Germany.,Free University of Berlin, Institute of Chemistry and Biochemistry, Fabeckstr. 34-36, 14195 Berlin, Germany
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129
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Ganley JM, Murray PRD, Knowles RR. Photocatalytic Generation of Aminium Radical Cations for C─N Bond Formation. ACS Catal 2020; 10:11712-11738. [PMID: 33163257 PMCID: PMC7644096 DOI: 10.1021/acscatal.0c03567] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Aminium radical cations have been extensively studied as electrophilic aminating species that readily participate in C─N bond forming processes with alkenes and arenes. However, their utility in synthesis has been limited, as their generation required unstable, reactive starting materials and harsh reaction conditions. Visible-light photoredox catalysis has emerged as a platform for the mild production of aminium radical cations from either unfunctionalized or N-functionalized amines. This Perspective covers recent synthetic methods that rely on the photocatalytic generation of aminium radical cations for C─N bond formation, specifically in the context of alkene hydroamination, arene C─H bond amination, and the mesolytic bond cleavage of alkoxyamines.
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Affiliation(s)
- Jacob M Ganley
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Philip R D Murray
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Robert R Knowles
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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130
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Donabauer K, Murugesan K, Rozman U, Crespi S, König B. Photocatalytic Reductive Radical-Polar Crossover for a Base-Free Corey-Seebach Reaction. Chemistry 2020; 26:12945-12950. [PMID: 32686166 PMCID: PMC7589390 DOI: 10.1002/chem.202003000] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/15/2020] [Indexed: 01/07/2023]
Abstract
A metal-free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey-Seebach reaction. The presented method operates under mild redox-neutral and base-free conditions giving the desired product with high functional group tolerance. The reaction is enabled by the combination of photo- and hydrogen atom transfer (HAT) catalysis. This catalytic merger allows a C-H to carbanion activation by the abstraction of a hydrogen atom followed by radical reduction. The generated nucleophilic intermediate is then capable of adding to carbonyl electrophiles. The obtained dithiane can be easily converted to the valuable α-hydroxy carbonyl in a subsequent step. The proposed reaction mechanism is supported by emission quenching, radical-radical homocoupling and deuterium labeling studies as well as by calculated redox-potentials and bond strengths.
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Affiliation(s)
- Karsten Donabauer
- Department of Organic ChemistryUniversity of RegensburgUniversitätsstraße 3193053RegensburgGermany
| | - Kathiravan Murugesan
- Department of Organic ChemistryUniversity of RegensburgUniversitätsstraße 3193053RegensburgGermany
| | - Urša Rozman
- Department of Organic ChemistryUniversity of RegensburgUniversitätsstraße 3193053RegensburgGermany
| | - Stefano Crespi
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Burkhard König
- Department of Organic ChemistryUniversity of RegensburgUniversitätsstraße 3193053RegensburgGermany
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131
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Declas N, Waser J. Access to Vinyl Ethers and Ketones with Hypervalent Iodine Reagents as Oxy‐Allyl Cation Synthetic Equivalents. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006707] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Nina Declas
- Laboratory of Catalysis and Organic Synthesis Ecole Polytechnique Fédérale de Lausanne, EPFL, SB ISIC LCSO, BCH 4306 1015 Lausanne Switzerland
| | - Jerome Waser
- Laboratory of Catalysis and Organic Synthesis Ecole Polytechnique Fédérale de Lausanne, EPFL, SB ISIC LCSO, BCH 4306 1015 Lausanne Switzerland
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132
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Bauer A, Di Mauro G, Li J, Maulide N. An α-Cyclopropanation of Carbonyl Derivatives by Oxidative Umpolung. Angew Chem Int Ed Engl 2020; 59:18208-18212. [PMID: 32808419 PMCID: PMC7589340 DOI: 10.1002/anie.202007439] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 06/11/2020] [Indexed: 11/10/2022]
Abstract
The reactivity of iodine(III) reagents towards nucleophiles is often associated with umpolung and cationic mechanisms. Herein, we report a general process converting a range of ketone derivatives into α-cyclopropanated ketones by oxidative umpolung. Mechanistic investigation and careful characterization of side products revealed that the reaction follows an unexpected pathway and suggests the intermediacy of non-classical carbocations.
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Affiliation(s)
- Adriano Bauer
- Institute of Organic ChemistryUniversity of ViennaWähringer Strasse 381090ViennaAustria
| | - Giovanni Di Mauro
- Institute of Organic ChemistryUniversity of ViennaWähringer Strasse 381090ViennaAustria
| | - Jing Li
- Department of ChemistryTohoku UniversityAoba-ku980-8578SendaiJapan
| | - Nuno Maulide
- Institute of Organic ChemistryUniversity of ViennaWähringer Strasse 381090ViennaAustria
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133
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Declas N, Waser J. Access to Vinyl Ethers and Ketones with Hypervalent Iodine Reagents as Oxy-Allyl Cation Synthetic Equivalents. Angew Chem Int Ed Engl 2020; 59:18256-18260. [PMID: 32542955 DOI: 10.1002/anie.202006707] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/08/2020] [Indexed: 12/18/2022]
Abstract
We report an Umpolung strategy of enol ethers to generate oxy-allyl cation equivalents based on the use of hypervalent iodine reagents. Under mild basic conditions, the addition of nucleophiles to aryloxy-substituted vinylbenziodoxolone (VBX) reagents, easily available in two steps from silyl alkynes, resulted in the stereoselective formation of substituted aryl enol ethers. The reaction was most efficient with phenols as nucleophiles, but preliminary results were also achieved for C- and N- nucleophiles. In absence of external nucleophiles, the 2-iodobenzoate group of the reagent was transferred. The obtained aryl enol ethers could then be transformed into α-difunctionalized ketones by oxidation. The described "allyl cation"-like reactivity contrast with the well-established "vinyl-cation" behavior of alkenyl iodonium salts.
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Affiliation(s)
- Nina Declas
- Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL, SB ISIC LCSO, BCH 4306, 1015, Lausanne, Switzerland
| | - Jerome Waser
- Laboratory of Catalysis and Organic Synthesis, Ecole Polytechnique Fédérale de Lausanne, EPFL, SB ISIC LCSO, BCH 4306, 1015, Lausanne, Switzerland
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134
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Zhang Z, Huang S, Huang L, Xu X, Zhao H, Yan X. Synthesis of Mesoionic N-Heterocyclic Olefins and Catalytic Application for Hydroboration Reactions. J Org Chem 2020; 85:12036-12043. [DOI: 10.1021/acs.joc.0c00257] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Zengyu Zhang
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Shiqing Huang
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Linwei Huang
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Xingyu Xu
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Hongyan Zhao
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Xiaoyu Yan
- Department of Chemistry, Renmin University of China, Beijing 100872, China
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135
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Arava S, Santra SK, Pathe GK, Kapanaiah R, Szpilman AM. Direct Umpolung Morita–Baylis–Hillman like α‐Functionalization of Enones via Enolonium Species. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202005286] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Shlomy Arava
- Department of Chemical Sciences Ariel University Ramat Hagolan 65 Ariel Israel
| | - Sourav K. Santra
- Department of Chemical Sciences Ariel University Ramat Hagolan 65 Ariel Israel
| | - Gulab K. Pathe
- Department of Chemical Sciences Ariel University Ramat Hagolan 65 Ariel Israel
| | - Raja Kapanaiah
- Department of Chemical Sciences Ariel University Ramat Hagolan 65 Ariel Israel
| | - Alex M. Szpilman
- Department of Chemical Sciences Ariel University Ramat Hagolan 65 Ariel Israel
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136
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Arava S, Santra SK, Pathe GK, Kapanaiah R, Szpilman AM. Direct Umpolung Morita-Baylis-Hillman like α-Functionalization of Enones via Enolonium Species. Angew Chem Int Ed Engl 2020; 59:15171-15175. [PMID: 32394609 DOI: 10.1002/anie.202005286] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Indexed: 12/13/2022]
Abstract
Herein we report on the umpolung of Morita-Baylis-Hillman type intermediates and application to the α-functionalization of enone C-H bonds. This reaction gives direct access to α-chloro-enones, 1,2-diketones and α-tosyloxy-enones. The latter are important intermediates for cross-coupling reaction and, to the best of our knowledge, cannot be made in a single step from enones in any other way. The proposed mechanism is supported by spectroscopic studies. The key initial step involves conjugate attack of an amine (DABCO or pyridine), likely assisted by hypervalent iodine acting as a Lewis acid leading to formation of an electrophilic β-ammonium-enolonium species. Nucleophilic attack by acetate, tosylate, or chloride anion is followed by base induced elimination of the ammonium species to give the noted products. Hydrolysis of α-acetoxy-enones lead to formation of 1,2-diketones. The α-tosyl-enones participate in Negishi coupling reactions under standard conditions.
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Affiliation(s)
- Shlomy Arava
- Department of Chemical Sciences, Ariel University, Ramat Hagolan 65, Ariel, Israel
| | - Sourav K Santra
- Department of Chemical Sciences, Ariel University, Ramat Hagolan 65, Ariel, Israel
| | - Gulab K Pathe
- Department of Chemical Sciences, Ariel University, Ramat Hagolan 65, Ariel, Israel
| | - Raja Kapanaiah
- Department of Chemical Sciences, Ariel University, Ramat Hagolan 65, Ariel, Israel
| | - Alex M Szpilman
- Department of Chemical Sciences, Ariel University, Ramat Hagolan 65, Ariel, Israel
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137
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Matador E, de Gracia Retamosa M, Monge D, Fernández R, Lassaletta JM. Formaldehyde tert-butyl hydrazone as a formyl anion equivalent: asymmetric addition to carbonyl compounds. Chem Commun (Camb) 2020; 56:9256-9267. [PMID: 32626864 DOI: 10.1039/d0cc02660c] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The asymmetric 1,2-addition of formyl anion equivalents to carbonyl compounds is a powerful synthetic tool that ideally provide access to highly functionalizable α-hydroxy aldehydes in an enantioselective fashion. In this context, the nucleophilic character of formaldehyde hydrazones, together with their remarkable stability as monomeric species, has been exploited for the functionalization of diverse carbonyl compounds, using initially auxiliary-based methodologies and, more recently, catalytic enantioselective versions. This feature article highlights our research progress employing formaldehyde tert-butyl hydrazone as a versatile formyl anion equivalent, in combination with bifunctional H-bonding organocatalysis. The design and optimization of different catalytic systems, focusing on a dual activation of both reagents, is reviewed, as well as the racemization free unmasking of the formyl group and representative product transformations for the construction of valuable, densely functionalyzed chiral building blocks.
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Affiliation(s)
- Esteban Matador
- Departamento de Química Orgánica, Universidad de Sevilla and Centro de Innovación Avanzada (ORFEO-CINQA), C/Prof. García González, 1, 41012 Sevilla, Spain.
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138
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Bauer A, Di Mauro G, Li J, Maulide N. An α‐Cyclopropanation of Carbonyl Derivatives by Oxidative Umpolung. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202007439] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Adriano Bauer
- Institute of Organic Chemistry University of Vienna Währinger Strasse 38 1090 Vienna Austria
| | - Giovanni Di Mauro
- Institute of Organic Chemistry University of Vienna Währinger Strasse 38 1090 Vienna Austria
| | - Jing Li
- Department of Chemistry Tohoku University Aoba-ku 980-8578 Sendai Japan
| | - Nuno Maulide
- Institute of Organic Chemistry University of Vienna Währinger Strasse 38 1090 Vienna Austria
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139
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Im H, Choi W, Hong S. Photocatalytic Vicinal Aminopyridylation of Methyl Ketones by a Double Umpolung Strategy. Angew Chem Int Ed Engl 2020; 59:17511-17516. [DOI: 10.1002/anie.202008435] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Indexed: 11/07/2022]
Affiliation(s)
- Honggu Im
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Wonjun Choi
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Sungwoo Hong
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
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140
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Im H, Choi W, Hong S. Photocatalytic Vicinal Aminopyridylation of Methyl Ketones by a Double Umpolung Strategy. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008435] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Honggu Im
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Wonjun Choi
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Sungwoo Hong
- Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
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141
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Wang W, Xiong Q, Gong L, Wang Y, Liu J, Lan Y, Zhang X. Regio- and Enantioselective Palladium-Catalyzed Asymmetric Allylation of N-Fluorenyl Trifluoromethyl Imine. Org Lett 2020; 22:5479-5485. [PMID: 32602723 DOI: 10.1021/acs.orglett.0c01836] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A palladium-catalyzed asymmetric allylation of N-fluorenyl trifluoromethyl imine with allylic acetates is disclosed. This method provides scalable and efficient access to polysubstituted chiral α-trifluoromethyl amines bearing two adjacent stereocenters and one allyl group in high yields with excellent regio-, diastereo-, and enantioselectivity. Importantly, this method also provides a powerful strategy for the synthesis of both regioisomeric products and the regioselectivity is controlled by the chiral catalysts and optically active substrates.
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Affiliation(s)
- Wei Wang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, P.R. China.,Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province/College of Chemistry & Chemical Engineering, China West Normal University, Nanchong 637009, P.R. China
| | - Qin Xiong
- College of Chemistry, and Institute of Green Catalysis, Zhengzhou University, Zhengzhou 450001, P.R. China.,School of Chemistry and Chemical Engineering, and Chongqing Key Laboratory of Theoretical and Computational Chemistry, Chongqing University, Chongqing 400030, P.R. China
| | - Liang Gong
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, P.R. China
| | - Yingwei Wang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, P.R. China
| | - Jie Liu
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, P.R. China
| | - Yu Lan
- College of Chemistry, and Institute of Green Catalysis, Zhengzhou University, Zhengzhou 450001, P.R. China.,School of Chemistry and Chemical Engineering, and Chongqing Key Laboratory of Theoretical and Computational Chemistry, Chongqing University, Chongqing 400030, P.R. China
| | - Xia Zhang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, P.R. China
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142
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Chen X, Wang H, Jin Z, Chi YR. N
‐Heterocyclic
Carbene Organocatalysis: Activation Modes and Typical Reactive Intermediates. CHINESE J CHEM 2020. [DOI: 10.1002/cjoc.202000107] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Xingkuan Chen
- Department of Chemistry, Jinan University Guangzhou Guangdong 510632 China
| | - Hongling Wang
- Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Guizhou University Huaxi District Guiyang Guizhou 550025 China
| | - Zhichao Jin
- Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Guizhou University Huaxi District Guiyang Guizhou 550025 China
| | - Yonggui Robin Chi
- Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Guizhou University Huaxi District Guiyang Guizhou 550025 China
- Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University Singapore 637371 Singapore
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143
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Ye Y, Kevlishvili I, Feng S, Liu P, Buchwald SL. Highly Enantioselective Synthesis of Indazoles with a C3-Quaternary Chiral Center Using CuH Catalysis. J Am Chem Soc 2020; 142:10550-10556. [PMID: 32408745 DOI: 10.1021/jacs.0c04286] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
C3-substituted 1H-indazoles are useful and important substructures in many pharmaceuticals. Methods for direct C3-functionalization of indazoles are relatively rare, compared to reactions developed for the more nucleophilic N1 and N2 positions. Herein, we report a highly C3-selective allylation reaction of 1H-N-(benzoyloxy)indazoles using CuH catalysis. A variety of C3-allyl 1H-indazoles with quaternary stereocenters were efficiently prepared with high levels of enantioselectivity. Density functional theory (DFT) calculations were performed to explain the reactivity differences between indazole and indole electrophiles, the latter of which was used in our previously reported method. The calculations suggest that the indazole allylation reaction proceeds through an enantioselectivity-determining six-membered Zimmerman-Traxler-type transition state, rather than an oxidative addition/reductive elimination sequence, as we proposed in the case of indole alkylation. The enantioselectivity of the reaction is governed by both ligand-substrate steric interactions and steric repulsions involving the pseudoaxial substituent in the six-membered allylation transition state.
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Affiliation(s)
- Yuxuan Ye
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Ilia Kevlishvili
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Sheng Feng
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Peng Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Stephen L Buchwald
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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144
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Nagaraju K, Gurubrahamam R, Chen K. Organocatalytic Diastereoselective Synthesis of Diazoaryl-benzo[b]azepine Derivatives. J Org Chem 2020; 85:7060-7067. [DOI: 10.1021/acs.joc.0c00431] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Koppanathi Nagaraju
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan, ROC
| | - Ramani Gurubrahamam
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan, ROC
- Department of Chemistry, Indian Institute of Technology Jammu, Jagti, NH 44, Jammu (J&K) 181221, India
| | - Kwunmin Chen
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan, ROC
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145
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Trageser T, Bolte M, Lerner HW, Wagner M. B-B Bond Nucleophilicity in a Tetraaryl μ-Hydridodiborane(4) Anion. Angew Chem Int Ed Engl 2020; 59:7726-7731. [PMID: 32058652 PMCID: PMC7317828 DOI: 10.1002/anie.202000292] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Indexed: 11/15/2022]
Abstract
The tetraaryl μ‐hydridodiborane(4) anion [2H]− possesses nucleophilic B−B and B−H bonds. Treatment of K[2H] with the electrophilic 9‐H‐9‐borafluorene (HBFlu) furnishes the B3 cluster K[3], with a triangular boron core linked through two BHB two‐electron, three‐center bonds and one electron‐precise B−B bond, reminiscent of the prominent [B3H8]− anion. Upon heating or prolonged stirring at room temperature, K[3] rearranges to a slightly more stable isomer K[3 a]. The reaction of M[2H] (M+=Li+, K+) with MeI or Me3SiCl leads to equimolar amounts of 9‐R‐9‐borafluorene and HBFlu (R=Me or Me3Si). Thus, [2H]− behaves as a masked [:BFlu]− nucleophile. The HBFlu by‐product was used in situ to establish a tandem substitution‐hydroboration reaction: a 1:1 mixture of M[2H] and allyl bromide gave the 1,3‐propylene‐linked ditopic 9‐borafluorene 5 as sole product. M[2H] also participates in unprecedented [4+1] cycloadditions with dienes to furnish dialkyl diaryl spiroborates, M[R2BFlu].
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Affiliation(s)
- Timo Trageser
- Institut für Anorganische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt (Main), Germany
| | - Michael Bolte
- Institut für Anorganische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt (Main), Germany
| | - Hans-Wolfram Lerner
- Institut für Anorganische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt (Main), Germany
| | - Matthias Wagner
- Institut für Anorganische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt (Main), Germany
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146
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Liu YC, Reddy DM, Chen XA, Shieh YC, Lee CF. Blue LED-Promoted Oxathiacetalization of Aldehydes and Ketones. European J Org Chem 2020. [DOI: 10.1002/ejoc.202000218] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- You-Chen Liu
- Department of Chemistry; National Chung Hsing University; 145 Xingda Rd., South Dist. 402 Taichung City Taiwan R.O.C
| | - Daggula Mallikarjuna Reddy
- Department of Chemistry; National Chung Hsing University; 145 Xingda Rd., South Dist. 402 Taichung City Taiwan R.O.C
| | - Xin-An Chen
- Department of Chemistry; National Chung Hsing University; 145 Xingda Rd., South Dist. 402 Taichung City Taiwan R.O.C
| | - Yi-Chen Shieh
- Department of Chemistry; National Chung Hsing University; 145 Xingda Rd., South Dist. 402 Taichung City Taiwan R.O.C
| | - Chin-Fa Lee
- Department of Chemistry; National Chung Hsing University; 145 Xingda Rd., South Dist. 402 Taichung City Taiwan R.O.C
- Research Center for Sustainable Energy and Nanotechnology (RCSEN); Taichung Taiwan R.O.C
- Innovation and Development Center of Sustainable Agriculture (IDCSA); Taichung Taiwan R.O.C
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147
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Wang S, Cheng BY, Sršen M, König B. Umpolung Difunctionalization of Carbonyls via Visible-Light Photoredox Catalytic Radical-Carbanion Relay. J Am Chem Soc 2020; 142:7524-7531. [PMID: 32233431 PMCID: PMC7252948 DOI: 10.1021/jacs.0c00629] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Indexed: 12/13/2022]
Abstract
The combination of photoredox catalysis with the Wolff-Kishner (WK) reaction allows the difunctionalization of carbonyl groups by a radical-carbanion relay sequence (photo-Wolff-Kishner reaction). Photoredox initiated radical addition to N-sulfonylhydrazones yields α-functionalized carbanions following the WK-type mechanism. With sulfur-centered radicals, the carbanions are further functionalized by reaction with electrophiles including CO2 and aldehydes, whereas CF3 radical addition furnishes a wide range of gem-difluoroalkenes through β-fluoride elimination of the generated α-CF3 carbanions. More than 80 substrate examples demonstrate the broad applicability of this reaction sequence. A series of investigations including radical inhibition, deuterium labeling, fluorescence quenching, cyclic voltammetry, and control experiments support the proposed radical-carbanion relay mechanism.
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Affiliation(s)
- Shun Wang
- Institute of Organic Chemistry, Faculty
of Chemistry and Pharmacy, University of
Regensburg, D-93040 Regensburg, Germany
| | - Bei-Yi Cheng
- Institute of Organic Chemistry, Faculty
of Chemistry and Pharmacy, University of
Regensburg, D-93040 Regensburg, Germany
| | - Matea Sršen
- Institute of Organic Chemistry, Faculty
of Chemistry and Pharmacy, University of
Regensburg, D-93040 Regensburg, Germany
| | - Burkhard König
- Institute of Organic Chemistry, Faculty
of Chemistry and Pharmacy, University of
Regensburg, D-93040 Regensburg, Germany
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148
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Trageser T, Bolte M, Lerner H, Wagner M. B−B Bond Nucleophilicity in a Tetraaryl μ‐Hydridodiborane(4) Anion. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202000292] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Timo Trageser
- Institut für Anorganische Chemie Goethe-Universität Frankfurt Max-von-Laue-Strasse 7 60438 Frankfurt (Main) Germany
| | - Michael Bolte
- Institut für Anorganische Chemie Goethe-Universität Frankfurt Max-von-Laue-Strasse 7 60438 Frankfurt (Main) Germany
| | - Hans‐Wolfram Lerner
- Institut für Anorganische Chemie Goethe-Universität Frankfurt Max-von-Laue-Strasse 7 60438 Frankfurt (Main) Germany
| | - Matthias Wagner
- Institut für Anorganische Chemie Goethe-Universität Frankfurt Max-von-Laue-Strasse 7 60438 Frankfurt (Main) Germany
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149
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Yan J, Song Z, Zhao C, Shi K, Yang L, Zhong G. Highly Chemoselective and Enantioselective Synthesis of 3,4-2 H-Pyrindin-2-ones by an NHC-Catalyzed [3 + 3] Cyclization. Org Lett 2020; 22:3329-3334. [PMID: 32157889 DOI: 10.1021/acs.orglett.0c00699] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A highly chemoselective and enantioselective cyclization of γ-chloroenals and ketimines has been developed to synthesize enantiopure 3,4-2H-pyrindin-2-ones as major products. It is proposed that the intermediate enone IV reacted with an enamine to proceed with a [3 + 3] cyclization, thereby affording 3,4-2H-pyrindin-2-ones as major products. Interestingly, the addition of LiCl promoted the formation of the enamine and accelerated the [3 + 3] cyclization. In contrast, the [4 + 2] cycloaddition reaction between the intermediate vinyl enolate VIII and an imine offered 5,6-2H-pyrindin-2-ones as minor products. This protocol represents the exceptional potential of N-heterocyclic carbene (NHC) catalytic reactions in accessing biologically active 3,4-2H-pyrindin-2-one derivatives in good yield with high chemoselectivities and excellent enantiomeric purities.
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Affiliation(s)
- Jun Yan
- College of Materials, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 311121, China
| | - Zhaoxin Song
- College of Materials, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 311121, China
| | - Chengtao Zhao
- College of Materials, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 311121, China
| | - Kuangxi Shi
- College of Materials, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 311121, China
| | - Limin Yang
- College of Materials, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 311121, China
| | - Guofu Zhong
- College of Materials, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 311121, China
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150
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Onyeagusi CI, Shao X, Malcolmson SJ. Enantio- and Diastereoselective Synthesis of Homoallylic α-Trifluoromethyl Amines by Catalytic Hydroalkylation of Dienes. Org Lett 2020; 22:1681-1685. [PMID: 32013445 PMCID: PMC7079280 DOI: 10.1021/acs.orglett.0c00342] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We describe a strategy for the enantio- and diastereoselective synthesis of homoallylic α-trifluoromethyl amines by the catalytic hydroalkylation of terminal dienes. Trifluoromethyl-substituted isatin-derived azadienolate nucleophiles undergo γ-selective alkylation with a Pd-DTBM-SEGPHOS catalyst, which additionally promotes regioselective addition to the diene and delivers products in up to 86% yield, 10:1 dr, and 97.5:2.5 er.
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Affiliation(s)
- Chibueze I Onyeagusi
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
| | - Xinxin Shao
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
| | - Steven J Malcolmson
- Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States
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