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Sarkar K, Behera P, Roy L, Maji B. Manganese catalyzed chemo-selective synthesis of acyl cyclopentenes: a combined experimental and computational investigation. Chem Sci 2024:d4sc02842b. [PMID: 39149218 PMCID: PMC11322900 DOI: 10.1039/d4sc02842b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 08/02/2024] [Indexed: 08/17/2024] Open
Abstract
Cyclopentenes serve as foundational structures in numerous natural products and pharmaceuticals. Consequently, the pursuit of innovative synthetic approaches to complement existing protocols is of paramount importance. In this context, we present a novel synthesis route for acyl cyclopentenes through a cascade reaction involving an acceptorless-dehydrogenative coupling of cyclopropyl methanol with methyl ketone, followed by a radical-initiated ring expansion rearrangement of the in situ formed vinyl cyclopropenone intermediate. The reaction, catalyzed by an earth-abundant metal complex, occurs under milder conditions, generating water and hydrogen gas as byproducts. Rigorous control experiments and detailed computational studies were conducted to unravel the underlying mechanism. The observed selectivity is explained by entropy-driven alcohol-assisted hydrogen liberation from an Mn-hydride complex, prevailing over the hydrogenation of unsaturated cyclopentenes.
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Affiliation(s)
- Koushik Sarkar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata Mohanpur 741246 West Bengal India
| | - Prativa Behera
- Institute of Chemical Technology Mumbai, IOC Odisha Campus Bhubaneswar Bhubaneswar 751013 India
| | - Lisa Roy
- Institute of Chemical Technology Mumbai, IOC Odisha Campus Bhubaneswar Bhubaneswar 751013 India
| | - Biplab Maji
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata Mohanpur 741246 West Bengal India
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2
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Smith LB, Armstrong RJ, Hou J, Smith E, Sze M, Sterling AJ, Smith A, Duarte F, Donohoe TJ. Redox Reorganization: Aluminium Promoted 1,5-Hydride Shifts Allow the Controlled Synthesis of Multisubstituted Cyclohexenes. Angew Chem Int Ed Engl 2023; 62:e202307424. [PMID: 37358307 PMCID: PMC10953022 DOI: 10.1002/anie.202307424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 06/21/2023] [Accepted: 06/26/2023] [Indexed: 06/27/2023]
Abstract
An efficient synthesis of cyclohexenes has been achieved from easily accessible tetrahydropyrans via a tandem 1,5-hydride shift-aldol condensation. We discovered that readily available aluminium reagents, e.g. Al2 O3 or Al(Ot Bu)3 are essential for this process, promoting the 1,5-hydride shift with complete regio- and enantiospecificity (in stark contrast to results obtained under basic conditions). The mild conditions, coupled with multiple methods available to access the tetrahydropyran starting materials makes this a versatile method with exceptional functional group tolerance. A wide range of cyclohexenes (>40 examples) have been prepared, many in enantiopure form, showing our ability to selectively install a substituent at each position around the newly forged cyclohexene ring. Experimental and computational studies revealed that aluminium serves a dual role in facilitating the hydride shift, activating both the alkoxide nucleophile and the electrophilic carbonyl group.
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Affiliation(s)
- Lewis B. Smith
- Chemistry Research LaboratoryUniversity of OxfordOX1 3TAOxfordUK
| | - Roly J. Armstrong
- Chemistry Research LaboratoryUniversity of OxfordOX1 3TAOxfordUK
- School of Natural and Environmental SciencesNewcastle UniversityNE1 7RUNewcastle Upon TyneUK
| | - Jingyan Hou
- Chemistry Research LaboratoryUniversity of OxfordOX1 3TAOxfordUK
| | - Edward Smith
- Chemistry Research LaboratoryUniversity of OxfordOX1 3TAOxfordUK
| | - Ming Sze
- Chemistry Research LaboratoryUniversity of OxfordOX1 3TAOxfordUK
| | | | - Alex Smith
- Syngenta, Jealott's Hill International Research CentreRG42 6EYBracknellBerkshireUK
| | - Fernanda Duarte
- Chemistry Research LaboratoryUniversity of OxfordOX1 3TAOxfordUK
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3
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Bains AK, Biswas A, Kundu A, Adhikari D. Nickel‐Catalysis Enabling α‐Alkylation of Ketones by Secondary Alcohols. Adv Synth Catal 2022. [DOI: 10.1002/adsc.202200522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Amreen K Bains
- Department of Chemical Sciences Indian Institute of Science Education and Research (IISER) – Mohali SAS Nagar Punjab-140306 India
| | - Ayanangshu Biswas
- Department of Chemical Sciences Indian Institute of Science Education and Research (IISER) – Mohali SAS Nagar Punjab-140306 India
| | - Abhishek Kundu
- Department of Chemical Sciences Indian Institute of Science Education and Research (IISER) – Mohali SAS Nagar Punjab-140306 India
| | - Debashis Adhikari
- Department of Chemical Sciences Indian Institute of Science Education and Research (IISER) – Mohali SAS Nagar Punjab-140306 India
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4
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Bains AK, Kundu A, Maiti D, Adhikari D. Ligand-redox assisted nickel catalysis toward stereoselective synthesis of ( n+1)-membered cycloalkanes from 1, n-diols with methyl ketones. Chem Sci 2021; 12:14217-14223. [PMID: 34760207 PMCID: PMC8565367 DOI: 10.1039/d1sc04261k] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/04/2021] [Indexed: 01/16/2023] Open
Abstract
A well-defined, bench-stable nickel catalyst is presented here, that can facilitate double alkylation of a methyl ketone to realize a wide variety of cycloalkanes. The performance of the catalyst depends on the ligand redox process comprising an azo-hydrazo couple. The source of the bis electrophile in this double alkylation is a 1,n-diol, so that (n+1)-membered cycloalkanes can be furnished in a stereoselective manner. The reaction follows a cascade of dehydrogenation/hydrogenation reactions and adopts a borrowing hydrogen (BH) method. A thorough mechanistic analysis including the interception of key radical intermediates and DFT calculations supports the ligand radical-mediated dehydrogenation and hydrogenation reactions, which is quite rare in BH chemistry. In particular, this radical-promoted hydrogenation is distinctly different from conventional hydrogenations involving a metal hydride and complementary to the ubiquitous two-electron driven dehydrogenation/hydrogenation reactions.
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Affiliation(s)
- Amreen K Bains
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER)-Mohali SAS Nagar Punjab-140306 India
| | - Abhishek Kundu
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER)-Mohali SAS Nagar Punjab-140306 India
| | - Debabrata Maiti
- Department of Chemistry, Indian Institute of Technology Bombay, Powai Mumbai-400076 India
| | - Debashis Adhikari
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER)-Mohali SAS Nagar Punjab-140306 India
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5
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Bera S, Kabadwal LM, Banerjee D. Recent advances in transition metal-catalyzed (1, n) annulation using (de)-hydrogenative coupling with alcohols. Chem Commun (Camb) 2021; 57:9807-9819. [PMID: 34486592 DOI: 10.1039/d1cc03404a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
(1,n) annulation reactions using (de)-hydrogenative coupling with alcohols or diols represent a straightforward technique for the synthesis of cyclic moieties. Utilization of such renewable resources for chemical transformations in a one-pot manner is the main focus, which avoids generation of stoichiometric waste. Application of such (1,n) annulation approaches drives the catalysis research in a more sustainable way and generates dihydrogen and water as by-products. This feature article highlights the recent (from 2015 to March 2021) progress in the synthesis of stereo-selective cycloalkanes and cycloalkenes, saturated and unsaturated N-heterocycles (cyclic amine, imide, lactam, tetrahydro β-carboline, quinazoline, quinazolinone, 1,3,5-triazines etc.) and other N-heterocycles with the formation of multiple bonds in a one pot operation. Mechanistic studies, new catalytic approaches, and synthetic applications including drug synthesis and post-drug derivatization, scope, and limitations are discussed.
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Affiliation(s)
- Sourajit Bera
- Department of Chemistry, Laboratory of Catalysis and Organic Synthesis, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India.
| | - Lalit Mohan Kabadwal
- Department of Chemistry, Laboratory of Catalysis and Organic Synthesis, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India.
| | - Debasis Banerjee
- Department of Chemistry, Laboratory of Catalysis and Organic Synthesis, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India.
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Frost JR, Cheong CB, Akhtar WM, Caputo DF, Christensen KE, Stevenson NG, Donohoe TJ. Hydrogen borrowing catalysis using 1° and 2° alcohols: Investigation and scope leading to α and β branched products. Tetrahedron 2021. [DOI: 10.1016/j.tet.2021.132051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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8
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Hall CJJ, Goundry WRF, Donohoe TJ. Hydrogen-Borrowing Alkylation of 1,2-Amino Alcohols in the Synthesis of Enantioenriched γ-Aminobutyric Acids. Angew Chem Int Ed Engl 2021; 60:6981-6985. [PMID: 33561302 PMCID: PMC8048514 DOI: 10.1002/anie.202100922] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Indexed: 12/22/2022]
Abstract
For the first time we have been able to employ enantiopure 1,2-amino alcohols derived from abundant amino acids in C-C bond-forming hydrogen-borrowing alkylation reactions. These reactions are facilitated by the use of the aryl ketone Ph*COMe. Racemisation of the amine stereocentre during alkylation can be prevented by the use of sub-stoichiometric base and protection of the nitrogen with a sterically hindered triphenylmethane (trityl) or benzyl group. The Ph* and trityl groups are readily cleaved in one pot to give γ-aminobutyric acid (GABA) products as their HCl salts without further purification. Both steps may be performed in sequence without isolation of the hydrogen-borrowing intermediate, removing the need for column chromatography.
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Affiliation(s)
- Christopher J. J. Hall
- Department of ChemistryUniversity of OxfordChemistry Research LaboratoryMansfield RoadOxfordOX1 3TAUK
| | - William R. F. Goundry
- Early Chemical DevelopmentPharmaceutical Sciences, R&DAstraZenecaMacclesfieldSK10 2NAUK
| | - Timothy J. Donohoe
- Department of ChemistryUniversity of OxfordChemistry Research LaboratoryMansfield RoadOxfordOX1 3TAUK
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9
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Hydrogen‐Borrowing Alkylation of 1,2‐Amino Alcohols in the Synthesis of Enantioenriched γ‐Aminobutyric Acids. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202100922] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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10
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Dambatta MB, Santos J, Bolt RR, Morrill LC. Transition metal free α-C-alkylation of ketones using secondary alcohols. Tetrahedron 2020. [DOI: 10.1016/j.tet.2020.131571] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Kwok T, Hoff O, Armstrong RJ, Donohoe TJ. Control of Absolute Stereochemistry in Transition-Metal-Catalysed Hydrogen-Borrowing Reactions. Chemistry 2020; 26:12912-12926. [PMID: 32297370 PMCID: PMC7589454 DOI: 10.1002/chem.202001253] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/03/2020] [Indexed: 12/20/2022]
Abstract
Hydrogen-borrowing catalysis represents a powerful method for the alkylation of amine or enolate nucleophiles with non-activated alcohols. This approach relies upon a catalyst that can mediate a strategic series of redox events, enabling the formation of C-C and C-N bonds and producing water as the sole by-product. In the majority of cases these reactions have been employed to target achiral or racemic products. In contrast, the focus of this Minireview is upon hydrogen-borrowing-catalysed reactions in which the absolute stereochemical outcome of the process can be controlled. Asymmetric hydrogen-borrowing catalysis is rapidly emerging as a powerful approach for the synthesis of enantioenriched amine and carbonyl containing products and examples involving both C-N and C-C bond formation are presented. A variety of different approaches are discussed including use of chiral auxiliaries, asymmetric catalysis and enantiospecific processes.
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Affiliation(s)
- Timothy Kwok
- Chemistry Research LaboratoryUniversity of OxfordOxfordOX1 3TAUK
| | - Oskar Hoff
- Chemistry Research LaboratoryUniversity of OxfordOxfordOX1 3TAUK
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12
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Wübbolt S, Cheong CB, Frost JR, Christensen KE, Donohoe TJ. A Vinyl Cyclopropane Ring Expansion and Iridium-Catalyzed Hydrogen Borrowing Cascade. Angew Chem Int Ed Engl 2020; 59:11339-11344. [PMID: 32314851 PMCID: PMC7463175 DOI: 10.1002/anie.202003614] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 03/31/2020] [Indexed: 12/18/2022]
Abstract
A vinyl cyclopropane rearrangement embedded in an iridium-catalyzed hydrogen borrowing reaction enabled the formation of substituted stereo-defined cyclopentanes from Ph* methyl ketone and cyclopropyl alcohols. Mechanistic studies provide evidence for the ring-expansion reaction being the result of a cascade based on oxidation of the cyclopropyl alcohols, followed by aldol condensation with the pentamethyl phenyl-substituted ketone to form an enone containing the vinyl cyclopropane. Subsequent single electron transfer (SET) to this system initiates a rearrangement, and the catalytic cycle is completed by reduction of the new enone. This process allows for the efficient formation of diversely substituted cyclopentanes as well as the construction of complex bicyclic carbon skeletons containing up to four contiguous stereocentres, all with high diastereoselectivity.
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Affiliation(s)
- Simon Wübbolt
- Chemistry Research LaboratoryUniversity of OxfordOxfordOX1 3TAUK
| | | | - James R. Frost
- Chemistry Research LaboratoryUniversity of OxfordOxfordOX1 3TAUK
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13
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Wübbolt S, Cheong CB, Frost JR, Christensen KE, Donohoe TJ. A Vinyl Cyclopropane Ring Expansion and Iridium‐Catalyzed Hydrogen Borrowing Cascade. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202003614] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Simon Wübbolt
- Chemistry Research Laboratory University of Oxford Oxford OX1 3TA UK
| | - Choon Boon Cheong
- Chemistry Research Laboratory University of Oxford Oxford OX1 3TA UK
| | - James R. Frost
- Chemistry Research Laboratory University of Oxford Oxford OX1 3TA UK
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Bettoni L, Gaillard S, Renaud JL. Iron-Catalyzed α-Alkylation of Ketones with Secondary Alcohols: Access to β-Disubstituted Carbonyl Compounds. Org Lett 2020; 22:2064-2069. [PMID: 32091220 DOI: 10.1021/acs.orglett.0c00549] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
An iron-catalyzed borrowing hydrogen strategy has been applied in the synthesis of β-branched carbonyl compounds. Various secondary benzylic and aliphatic alcohols have been used as alkylating reagents under mild reaction conditions. The ketones have been isolated in good to excellent yield. Deuterium labeling experiments provide evidence that the alcohol is the hydride source in this reaction and that no reversible step or hydrogen/deuterium scrambling takes place during the process.
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Affiliation(s)
- Léo Bettoni
- Normandie Univ., LCMT, ENSICAEN, UNICAEN, CNRS, 6 boulevard du Maréchal Juin,14000 Caen, France
| | - Sylvain Gaillard
- Normandie Univ., LCMT, ENSICAEN, UNICAEN, CNRS, 6 boulevard du Maréchal Juin,14000 Caen, France
| | - Jean-Luc Renaud
- Normandie Univ., LCMT, ENSICAEN, UNICAEN, CNRS, 6 boulevard du Maréchal Juin,14000 Caen, France
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Smith LB, Armstrong RJ, Matheau-Raven D, Donohoe TJ. Chemo- and Regioselective Synthesis of Acyl-Cyclohexenes by a Tandem Acceptorless Dehydrogenation-[1,5]-Hydride Shift Cascade. J Am Chem Soc 2020; 142:2514-2523. [PMID: 31967814 PMCID: PMC7145340 DOI: 10.1021/jacs.9b12296] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
An
atom-economical methodology to access substituted acyl-cyclohexenes
from pentamethylacetophenone and 1,5-diols is described. This process is catalyzed by an
iridium(I) catalyst in conjunction with a bulky electron rich phosphine
ligand (CataCXium A) which favors acceptorless dehydrogenation over
conjugate reduction to the corresponding cyclohexane. The reaction
produces water and hydrogen gas as the sole byproducts and a wide
range of functionalized acyl-cyclohexene products can be synthesized
using this method in very high yields. A series of control experiments
were carried out, which revealed that the process is initiated by
acceptorless dehydrogenation of the diol followed by a redox-neutral
cascade process, which is independent of the iridium catalyst. Deuterium
labeling studies established that the key step of this cascade involves
a novel base-mediated [1,5]-hydride shift. The cyclohexenyl ketone
products could readily be cleaved under mildly acidic conditions to
access a range of valuable substituted cyclohexene derivatives.
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Affiliation(s)
- Lewis B Smith
- Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , United Kingdom
| | - Roly J Armstrong
- Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , United Kingdom
| | - Daniel Matheau-Raven
- Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , United Kingdom
| | - Timothy J Donohoe
- Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , United Kingdom
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Jana A, Das K, Kundu A, Thorve PR, Adhikari D, Maji B. A Phosphine-Free Manganese Catalyst Enables Stereoselective Synthesis of (1 + n)-Membered Cycloalkanes from Methyl Ketones and 1,n-Diols. ACS Catal 2020. [DOI: 10.1021/acscatal.9b05567] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Akash Jana
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
| | - Kuhali Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
| | - Abhishek Kundu
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, SAS Nagar 140306, India
| | - Pradip Ramdas Thorve
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
| | - Debashis Adhikari
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, SAS Nagar 140306, India
| | - Biplab Maji
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
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Bettoni L, Gaillard S, Renaud JL. A phosphine-free iron complex-catalyzed synthesis of cycloalkanes via the borrowing hydrogen strategy. Chem Commun (Camb) 2020; 56:12909-12912. [PMID: 32996937 DOI: 10.1039/d0cc05840h] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Herein we report a diaminocyclopentadienone iron tricarbonyl complex catalyzed synthesis of substituted cyclopentane, cyclohexane and cycloheptane compounds using the borrowing hydrogen strategy in the presence of various substituted primary and secondary 1,n diols as alkylating reagents. Deuterium labeling experiments confirm that the diols were the hydride source in this cascade process.
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Affiliation(s)
- Léo Bettoni
- Normandie Univ., LCMT, ENSICAEN, UNICAEN, CNRS, 6 Boulevard du Maréchal Juin, 14000 Caen, France.
| | - Sylvain Gaillard
- Normandie Univ., LCMT, ENSICAEN, UNICAEN, CNRS, 6 Boulevard du Maréchal Juin, 14000 Caen, France.
| | - Jean-Luc Renaud
- Normandie Univ., LCMT, ENSICAEN, UNICAEN, CNRS, 6 Boulevard du Maréchal Juin, 14000 Caen, France.
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Cheang DMJ, Armstrong RJ, Akhtar WM, Donohoe TJ. Enantioconvergent alkylation of ketones with racemic secondary alcohols via hydrogen borrowing catalysis. Chem Commun (Camb) 2020; 56:3543-3546. [DOI: 10.1039/d0cc00767f] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
An enantioconvergent hydrogen borrowing strategy enables the catalytic asymmetric alkylation of ketone enolates with unactivated, racemic secondary alcohols.
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Chamberlain AER, Paterson KJ, Armstrong RJ, Twin HC, Donohoe TJ. A hydrogen borrowing annulation strategy for the stereocontrolled synthesis of saturated aza-heterocycles. Chem Commun (Camb) 2020; 56:3563-3566. [DOI: 10.1039/d0cc00903b] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A hydrogen borrowing annulation strategy enables the stereocontrolled synthesis of C2, C3 and C4-substituted saturated aza-heterocycles.
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