1
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Adili A, Webster JP, Zhao C, Mallojjala SC, Romero-Reyes MA, Ghiviriga I, Abboud KA, Vetticatt MJ, Seidel D. Mechanism of a Dually Catalyzed Enantioselective Oxa-Pictet-Spengler Reaction and the Development of a Stereodivergent Variant. ACS Catal 2023; 13:2240-2249. [PMID: 37711191 PMCID: PMC10501388 DOI: 10.1021/acscatal.2c05484] [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] [Indexed: 01/28/2023]
Abstract
Enantioselective oxa-Pictet-Spengler reactions of tryptophol with aldehydes proceed under weakly acidic conditions utilizing a combination of two catalysts, an indoline HCl salt and a bisthiourea compound. Mechanistic investigations revealed the roles of both catalysts and confirmed the involvement of oxocarbenium ion intermediates, ruling out alternative scenarios. A stereochemical model was derived from density functional theory calculations, which provided the basis for the development of a highly enantioselective stereodivergent variant with racemic tryptophol derivatives.
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Affiliation(s)
- Alafate Adili
- Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - John-Paul Webster
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - Chenfei Zhao
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | | | - Moises A Romero-Reyes
- Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Ion Ghiviriga
- Center for NMR Spectroscopy, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Khalil A Abboud
- Center for X-ray Crystallography, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Mathew J Vetticatt
- Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States
| | - Daniel Seidel
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
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2
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Truax NJ, Ayinde S, Liu JO, Romo D. Total Synthesis of Rameswaralide Utilizing a Pharmacophore-Directed Retrosynthetic Strategy. J Am Chem Soc 2022; 144:18575-18585. [PMID: 36166374 DOI: 10.1021/jacs.2c08245] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A pharmacophore-directed retrosynthetic strategy was applied to the first total synthesis of the cembranoid rameswaralide in order to simultaneously achieve a total synthesis while also developing a structure-activity relationship profile throughout the synthetic effort. The synthesis utilized a Diels-Alder lactonization process, including a rare kinetic resolution to demonstrate the potential of this strategy for an enantioselective synthesis providing both the 5,5,6- and, through a ring expansion, 5,5,7-tricyclic ring systems present in several Sinularia soft coral cembranoids. A pivotal synthetic intermediate, a tricyclic epoxy α-bromo cycloheptenone, displayed high cytotoxicity with interesting selectivity toward the HCT-116 colon cancer cell line. This intermediate enabled the pursuit of three unique D-ring annulation strategies including a photocatalyzed intramolecular Giese-type radical cyclization and a diastereoselective, intramolecular enamine-mediated Michael addition, with the latter annulation constructing the final D-ring to deliver rameswaralide. The serendipitous discovery of an oxidation state transposition of the tricyclic epoxy cycloheptenone proceeding through a presumed doubly vinylogous, E1-type elimination enabled the facile introduction of the required α-methylene butyrolactone. Preliminary biological tests of rameswaralide and precursors demonstrated weak cytotoxicity; however, the comparable cytotoxicity of a simple 6,7-bicyclic β-keto ester, corresponding to the CD-ring system of rameswaralide, to that of the natural product itself suggests that such bicyclic β-ketoesters may constitute an interesting pharmacophore that warrants further exploration.
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Affiliation(s)
- Nathanyal J Truax
- Department of Chemistry & Biochemistry, Baylor University, 101 Bagby Avenue, Waco, Texas 76710, United States
| | - Safiat Ayinde
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205, United States
| | - Jun O Liu
- Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205, United States
| | - Daniel Romo
- Department of Chemistry & Biochemistry, Baylor University, 101 Bagby Avenue, Waco, Texas 76710, United States
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3
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Abstract
Differences in entropies of competing transition states can direct kinetic selectivity. Understanding and modeling such entropy differences at the molecular level is complicated by the fact that entropy is statistical in nature; i.e., it depends on multiple vibrational states of transition structures, the existence of multiple dynamically accessible pathways past these transition structures, and contributions from multiple transition structures differing in conformation/configuration. The difficulties associated with modeling each of these contributors are discussed here, along with possible solutions, all with an eye toward the development of portable qualitative models of use to experimentalists aiming to design reactions that make use of entropy to control kinetic selectivity.
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Affiliation(s)
- Dean J Tantillo
- Department of Chemistry, University of California-Davis, 1 Shields Ave, Davis, California 95616, United States
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4
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Hartley WC, Schiel F, Ermini E, Melchiorre P. Lewis Base‐Catalysed Enantioselective Radical Conjugate Addition for the Synthesis of Enantioenriched Pyrrolidinones. Angew Chem Int Ed Engl 2022; 61:e202204735. [DOI: 10.1002/anie.202204735] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Indexed: 12/15/2022]
Affiliation(s)
- Will C. Hartley
- ICIQ—Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
| | | | - Elena Ermini
- ICIQ—Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
| | - Paolo Melchiorre
- ICREA— Passeig Lluís Companys 23 08010 Barcelona Spain
- ICIQ—Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
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5
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Bitai J, Nimmo AJ, Slawin AMZ, Smith AD. Cooperative Palladium/Isothiourea Catalyzed Enantioselective Formal (3+2) Cycloaddition of Vinylcyclopropanes and α,β-Unsaturated Esters. Angew Chem Int Ed Engl 2022; 61:e202202621. [PMID: 35389553 PMCID: PMC9324207 DOI: 10.1002/anie.202202621] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Indexed: 12/15/2022]
Abstract
A protocol for the enantioselective synthesis of substituted vinylcyclopentanes has been realised using cooperative palladium and isothiourea catalysis. Treatment of vinylcyclopropanes with Pd(PPh3 )4 generates a zwitterionic π-allyl palladium intermediate that intercepts a catalytically generated α,β-unsaturated acyl ammonium species prepared from the corresponding α,β-unsaturated para-nitrophenyl ester and the isothiourea (R)-BTM. Intermolecular formal (3+2) cycloaddition between these reactive intermediates generates functionalised cyclopentanes in generally good yields and excellent diastereo- and enantiocontrol (up to >95 : 5 dr, 97 : 3 er), with the use of LiCl as an additive proving essential for optimal stereocontrol. To the best of our knowledge a dual transition metal/organocatalytic process involving α,β-unsaturated acyl ammonium intermediates has not been demonstrated previously.
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Affiliation(s)
- Jacqueline Bitai
- EaStCHEM, School of ChemistryUniversity of St AndrewsSt Andrews, FifeKY16 9STUK
| | - Alastair J. Nimmo
- EaStCHEM, School of ChemistryUniversity of St AndrewsSt Andrews, FifeKY16 9STUK
| | | | - Andrew D. Smith
- EaStCHEM, School of ChemistryUniversity of St AndrewsSt Andrews, FifeKY16 9STUK
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6
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Hartley WC, Schiel F, Ermini E, Melchiorre P. Lewis Base‐Catalysed Enantioselective Radical Conjugate Addition for the Synthesis of Enantioenriched Pyrrolidinones. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202204735] [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)
- Will C. Hartley
- ICIQ: Institut Catala d'Investigacio Quimica Iciq 43007 Tarragona SPAIN
| | - Florian Schiel
- ICIQ: Institut Catala d'Investigacio Quimica Iciq 43007 Tarragona SPAIN
| | - Elena Ermini
- ICIQ: Institut Catala d'Investigacio Quimica iciq 43007 Tarragona SPAIN
| | - Paolo Melchiorre
- Institute of Chemical Research of Catalonia (ICIQ) ICIQ Av. Països Catalans 16 43007 Tarragona SPAIN
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7
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Kurihara T, Kojima M, Yoshino T, Matsunaga S. Achiral Cp*Rh(III)/Chiral Lewis Base Cooperative Catalysis for Enantioselective Cyclization via C–H Activation. J Am Chem Soc 2022; 144:7058-7065. [DOI: 10.1021/jacs.2c01223] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Takumaru Kurihara
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Masahiro Kojima
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Tatsuhiko Yoshino
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
- Global Station for Biosurfaces and Drug Discovery, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan
| | - Shigeki Matsunaga
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
- Global Station for Biosurfaces and Drug Discovery, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo 060-0812, Japan
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8
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Bitai J, Nimmo AJ, Slawin AMZ, Smith AD. Cooperative Palladium/Isothiourea Catalyzed Enantioselective Formal (3+2) Cycloaddition of Vinylcyclopropanes and a,b‐Unsaturated Esters. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202202621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | | | | | - Andrew David Smith
- University of St Andrews School of Chemistry North Haugh FIFE, KY10 3TH St. Andrews UNITED KINGDOM
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9
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Sun Q, Lu X, Tantillo DJ. Dynamic Effects in Intramolecular Schmidt Reactions: Entropy, Electrostatic Drag, and Selectivity Prediction. Chemphyschem 2021; 22:649-656. [PMID: 33567140 DOI: 10.1002/cphc.202100033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Indexed: 12/16/2022]
Abstract
Electrostatic drag in the intramolecular Schmidt reactions of azidopropylcyclohexanones is characterized using density functional theory (DFT) calculations and direct dynamics simulations. Despite resulting from enthalpically favorable interactions, electrostatic drag slows down N2 loss during formation of bridged lactam products, an effect with implications for controlling product selectivity.
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Affiliation(s)
- Qing Sun
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang, 330063, China
| | - Xin Lu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Dean J Tantillo
- Department of Chemistry, University of California, Davis, CA 95616, USA
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10
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Tantillo DJ. Dynamic effects on organic reactivity—Pathways to (and from) discomfort. J PHYS ORG CHEM 2021. [DOI: 10.1002/poc.4202] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Dean J. Tantillo
- Department of Chemistry University of California, Davis Davis California USA
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11
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Bitai J, Westwood MT, Smith AD. α,β-Unsaturated acyl ammonium species as reactive intermediates in organocatalysis: an update. Org Biomol Chem 2021; 19:2366-2384. [PMID: 33650626 DOI: 10.1039/d0ob02208j] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
α,β-Unsaturated acyl ammonium species are versatile intermediates that have been applied in a variety of transformations including Michael additions, domino reactions and cycloadditions. Many of these transformations are promoted by chiral Lewis base catalysts, enabling the rapid generation of molecular complexity with high stereochemical control. This review highlights recent developments in the generation and application of α,β-unsaturated acyl ammonium intermediates reported since a previous review of this area in 2016. Particular emphasis will be placed on reports providing mechanistic insight into catalytic transformations and observed selectivities. A perspective on current challenges and potential future developments in the field of α,β-unsaturated acyl ammonium catalysis is also provided.
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Affiliation(s)
- Jacqueline Bitai
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, Fife, Scotland, KY16 9ST, UK.
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12
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13
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Chaheine CM, Song CJ, Gladen PT, Romo D. Enantioselective Michael-Proton Transfer-Lactamization for Pyroglutamic Acid Derivatives: Synthesis of Dimethyl-( S,E)-5-oxo-3-styryl-1-tosylpyrrolidine-2,2-dicarboxylate. ORGANIC SYNTHESES; AN ANNUAL PUBLICATION OF SATISFACTORY METHODS FOR THE PREPARATION OF ORGANIC CHEMICALS 2021; 98:194-226. [PMID: 36090506 PMCID: PMC9463714 DOI: 10.15227/orgsyn.098.0194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Affiliation(s)
| | - Conner J Song
- Department of Chemistry & Biochemistry, Baylor University, Waco, TX 76710
| | - Paul T Gladen
- Department of Chemistry & Biochemistry, Baylor University, Waco, TX 76710
| | - Daniel Romo
- Department of Chemistry & Biochemistry, Baylor University, Waco, TX 76710
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14
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Abstract
Covering: 1986 to 2020Natural products are an enduring source of chemical information useful for probing biologically relevant chemical space. Toward gathering further structure-activity relationship (SAR) information for a particular natural product, synthetic chemists traditionally proceeded first by a total synthesis effort followed by the synthesis of simplified derivatives. While this approach has proven fruitful, it often does not incorporate hypotheses regarding structural features necessary for bioactivity at the synthetic planning stage, but rather focuses on the rapid assembly of the targeted natural product; a goal that often supersedes the opportunity to gather SAR information en route to the natural product. Furthermore, access to simplified variants of a natural product possessing only the proposed essential structural features necessary for bioactivity, typically at lower oxidation states overall, is sometimes non-trivial from the original established synthetic route. In recent years, several synthetic design strategies were described to streamline the process of finding bioactive molecules in concert with fathering further SAR studies for targeted natural products. This review article will briefly discuss traditional retrosynthetic strategies and contrast them to selected examples of recent synthetic strategies for the investigation of biologically relevant chemical space revealed by natural products. These strategies include: diversity-oriented synthesis (DOS), biology-oriented synthesis (BIOS), diverted-total synthesis (DTS), analogue-oriented synthesis (AOS), two-phase synthesis, function-oriented synthesis (FOS), and computed affinity/dynamically ordered retrosynthesis (CANDOR). Finally, a description of pharmacophore-directed retrosynthesis (PDR) developed in our laboratory and initial applications will be presented that was initially inspired by a retrospective analysis of our synthetic route to pateamine A completed in 1998.
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Affiliation(s)
- Nathanyal J Truax
- Department of Chemistry & Biochemistry, Baylor University, Waco, Texas 76710, USA.
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15
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Biswas A, Mondal H, Maji MS. Synthesis of Heterocycles by isothiourea organocatalysis. J Heterocycl Chem 2020. [DOI: 10.1002/jhet.4119] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Anup Biswas
- Department of Chemistry Hooghly Women's College Hooghly India
| | - Haripriyo Mondal
- Department of Chemistry Indian Institute of Technology Kharagpur India
| | - Modhu S. Maji
- Department of Chemistry Indian Institute of Technology Kharagpur India
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16
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Li D, Wang S, Ge S, Dong S, Feng X. Asymmetric Synthesis of Axially Chiral Anilides via Organocatalytic Atroposelective N-Acylation. Org Lett 2020; 22:5331-5336. [DOI: 10.1021/acs.orglett.0c01581] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Dawei Li
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Sijing Wang
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Shulin Ge
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Shunxi Dong
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Xiaoming Feng
- Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China
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17
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Zhang YC, Geng RL, Song J, Gong LZ. Isothiourea and Brønsted Acid Cooperative Catalysis: Enantioselective Construction of Dihydropyridinones. Org Lett 2020; 22:2261-2265. [DOI: 10.1021/acs.orglett.0c00461] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Yu-Chen Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Rui-Long Geng
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Jin Song
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Liu-Zhu Gong
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
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18
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Liu H, Slawin AMZ, Smith AD. Isothiourea-Catalyzed Enantioselective Synthesis of Tetrahydro-α-carbolinones. Org Lett 2020; 22:1301-1305. [DOI: 10.1021/acs.orglett.9b04615] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Honglei Liu
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, U.K
| | - Alexandra M. Z. Slawin
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, U.K
| | - Andrew D. Smith
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, U.K
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19
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Matviitsuk A, Greenhalgh MD, Taylor JE, Nguyen XB, Cordes DB, Slawin AMZ, Lupton DW, Smith AD. Unanticipated Silyl Transfer in Enantioselective α,β-Unsaturated Acyl Ammonium Catalysis Using Silyl Nitronates. Org Lett 2019; 22:335-339. [DOI: 10.1021/acs.orglett.9b04404] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anastassia Matviitsuk
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, U.K
| | - Mark D. Greenhalgh
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, U.K
| | - James E. Taylor
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, U.K
| | - Xuan B. Nguyen
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - David B. Cordes
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, U.K
| | - Alexandra M. Z. Slawin
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, U.K
| | - David W. Lupton
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Andrew D. Smith
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, U.K
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20
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De Carvalho GSG, Granato ÁS, De Castro PP, Amarante GW. Recent Contributions of Nuclear Magnetic Resonance in Organocatalysis Mechanism Elucidation. CURRENT ORGANOCATALYSIS 2019. [DOI: 10.2174/2213337206666190328210907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
Nuclear Magnetic Resonance (NMR) is one of the most employed techniques
in structural elucidation of organic compounds. In addition to its use in structural characterization,
it has been widely employed in the investigation of reaction mechanisms, especially those involving
catalysis.
Objective:
In this review, we aim to provide recent examples of the interface of NMR and organocatalysis
reaction mechanism.
Methods:
Selected examples of different approaches for mechanism elucidation will be presented,
such as isotopic effect, catalyst labelling and online reaction monitoring. A discussion involving the
use of solid-state NMR will also be disclosed.
Conclusion:
NMR consists of a non-destructive technique, extremely useful in the real-time identification
of intermediates in crude reaction mixtures. With the advent of two-dimensional experiments
and high field NMR spectrometers, the reports of studies involving mechanistic elucidation were
greatly enhanced. In this context, nowadays NMR appears as a powerful tool for the comprehension
of reaction mechanisms, including the possibility of the proposal of unknown reaction mechanisms
within organocatalysis.
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Affiliation(s)
| | - Álisson Silva Granato
- Department of Chemistry, Federal University of Juiz de Fora, Campus Martelos, Juiz de Fora, Minas Gerais 36036900, Brazil
| | - Pedro Pôssa De Castro
- Department of Chemistry, Federal University of Juiz de Fora, Campus Martelos, Juiz de Fora, Minas Gerais 36036900, Brazil
| | - Giovanni Wilson Amarante
- Department of Chemistry, Federal University of Juiz de Fora, Campus Martelos, Juiz de Fora, Minas Gerais 36036900, Brazil
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21
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Shu C, Liu H, Slawin AMZ, Carpenter-Warren C, Smith AD. Isothiourea-catalysed enantioselective Michael addition of N-heterocyclic pronucleophiles to α,β-unsaturated aryl esters. Chem Sci 2019; 11:241-247. [PMID: 34040717 PMCID: PMC8133005 DOI: 10.1039/c9sc04303a] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The isothiourea-catalysed enantioselective Michael addition of 3-aryloxindole and 4-substituted-dihydropyrazol-3-one pronucleophiles to α,β-unsaturated p-nitrophenyl esters is reported. This process generates products containing two contiguous stereocentres, one quaternary, in good yields and excellent enantioselectivities (>30 examples, up to > 95 : 5 dr and 99 : 1 er). This protocol harnesses the multifunctional ability of p-nitrophenoxide to promote effective catalysis. In contrast to previous methodologies using tertiary amine Lewis bases, in which the pronucleophile was used as the solvent, this work allows bespoke pronucleophiles to be used in stoichiometric quantities. The isothiourea-catalysed enantioselective Michael addition of 3-aryloxindole and 4-substituted-dihydropyrazol-3-one pronucleophiles to α,β-unsaturated p-nitrophenyl esters is reported.![]()
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Affiliation(s)
- Chang Shu
- EaStCHEM, School of Chemistry, University of St Andrews North Haugh, St Andrews Fife KY16 9ST UK
| | - Honglei Liu
- EaStCHEM, School of Chemistry, University of St Andrews North Haugh, St Andrews Fife KY16 9ST UK
| | - Alexandra M Z Slawin
- EaStCHEM, School of Chemistry, University of St Andrews North Haugh, St Andrews Fife KY16 9ST UK
| | - Cameron Carpenter-Warren
- EaStCHEM, School of Chemistry, University of St Andrews North Haugh, St Andrews Fife KY16 9ST UK
| | - Andrew D Smith
- EaStCHEM, School of Chemistry, University of St Andrews North Haugh, St Andrews Fife KY16 9ST UK
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22
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Truax NJ, Ayinde S, Van K, Liu JO, Romo D. Pharmacophore-Directed Retrosynthesis Applied to Rameswaralide: Synthesis and Bioactivity of Sinularia Natural Product Tricyclic Cores. Org Lett 2019; 21:7394-7399. [PMID: 31498642 DOI: 10.1021/acs.orglett.9b02713] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A pharmacophore-directed retrosynthesis strategy applied to rameswaralide provided simplified precursors bearing the common 5,5,6 (red) and 5,5,7 (blue) skeleton present in several cembranoid and norcembranoids from Sinularia soft corals. Key steps include a Diels-Alder lactonization organocascade delivering the common 5,5,6 core and a subsequent ring expansion affording a 5,5,7 core serviceable for the synthesis of rameswaralide. Initial structure-activity relationships of intermediates en route to the natural product have revealed interesting differential and selective cytotoxicity.
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Affiliation(s)
- Nathanyal J Truax
- Department of Chemistry & Biochemistry , Baylor University , Waco , Texas 76710 , United States
| | - Safiat Ayinde
- Department of Pharmacology and Molecular Sciences , John Hopkins School of Medicine , 725 North Wolfe Street , Baltimore , Maryland 21205 , United States
| | - Khoi Van
- Department of Chemistry & Biochemistry , Baylor University , Waco , Texas 76710 , United States
| | - Jun O Liu
- Department of Pharmacology and Molecular Sciences , John Hopkins School of Medicine , 725 North Wolfe Street , Baltimore , Maryland 21205 , United States
| | - Daniel Romo
- Department of Chemistry & Biochemistry , Baylor University , Waco , Texas 76710 , United States
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23
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Synthesis of Fused Indoline‐Cyclobutanone Derivatives via an Intramolecular [2+2] Cycloaddition. European J Org Chem 2019. [DOI: 10.1002/ejoc.201900326] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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24
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Jarrige L, Glavač D, Levitre G, Retailleau P, Bernadat G, Neuville L, Masson G. Chiral phosphoric acid-catalyzed enantioselective construction of structurally diverse benzothiazolopyrimidines. Chem Sci 2019; 10:3765-3769. [PMID: 31015920 PMCID: PMC6461124 DOI: 10.1039/c8sc05581e] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 02/06/2019] [Indexed: 11/24/2022] Open
Abstract
A highly efficient catalytic enantioselective [4+2] cycloaddition was developed between 2-benzothiazolimines and enecarbamates. A wide range of benzothiazolopyrimidines bearing three contiguous stereogenic centers was obtained in high to excellent yields and with excellent diastereo- and enantioselectivities (d.r. > 98 : 2 and up to >99% ee). Furthermore, this chiral phosphoric acid-catalyzed strategy was scalable and enabled access to a new class of optically pure Lewis base isothiourea derivatives.
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Affiliation(s)
- Lucie Jarrige
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
| | - Danijel Glavač
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
- Ruđer Bošković Institute , Division of Organic Chemistry and Biochemistry , Bijenička cesta 54 , 10000 Zagreb , Croatia
| | - Guillaume Levitre
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
| | - Pascal Retailleau
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
| | - Guillaume Bernadat
- Laboratoire Chimie Thérapeutique , Faculté de Pharmacie Biocis 8076 , LabEx LERMIT , 5, rue J. B. Clément, 92296 Châtenay Malabry , France
| | - Luc Neuville
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
| | - Géraldine Masson
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
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25
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Abbasov ME, Alvariño R, Chaheine CM, Alonso E, Sánchez JA, Conner ML, Alfonso A, Jaspars M, Botana LM, Romo D. Simplified immunosuppressive and neuroprotective agents based on gracilin A. Nat Chem 2019; 11:342-350. [PMID: 30903037 PMCID: PMC6532426 DOI: 10.1038/s41557-019-0230-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 02/07/2019] [Indexed: 02/06/2023]
Abstract
The architecture and bioactivity of natural products frequently serve as embarkation points for the exploration of biologically relevant chemical space. Total synthesis followed by derivative synthesis has historically enabled a deeper understanding of structure-activity relationships. However, synthetic strategies towards a natural product are not always guided by hypotheses regarding the structural features required for bioactivity. Here, we report an approach to natural product total synthesis that we term 'pharmacophore-directed retrosynthesis'. A hypothesized, pharmacophore of a natural product is selected as an early synthetic target and this dictates the retrosynthetic analysis. In an ideal application, sequential increases in the structural complexity of this minimal structure enable development of a structure-activity relationship profile throughout the course of the total synthesis effort. This approach enables the identification of simpler congeners retaining bioactivity at a much earlier stage of a synthetic effort, as demonstrated here for the spongiane diterpenoid, gracilin A, leading to simplified derivatives with potent neuroprotective and immunosuppressive activity.
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Affiliation(s)
- Mikail E Abbasov
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA
| | - Rebeca Alvariño
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain
| | | | - Eva Alonso
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain
| | - Jon A Sánchez
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain
| | - Michael L Conner
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA
| | - Amparo Alfonso
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain
| | - Marcel Jaspars
- Marine Biodiscovery Centre, Department of Chemistry, University of Aberdeen, Aberdeen, Scotland, UK
| | - Luis M Botana
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain.
| | - Daniel Romo
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA.
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26
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Zhou M, He E, Zhang L, Chen J, Zhang Z, Liu Y, Zhang W. Development of a new bicyclic imidazole nucleophilic organocatalyst for direct enantioselective C-acylation. Org Chem Front 2019. [DOI: 10.1039/c9qo01025d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A new chiral nucleophilic organocatalyst bearing a 5,6,7,8-tetrahydroimidazo[1,2-a]pyridine skeleton has been developed.
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Affiliation(s)
- Muxing Zhou
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs
- School of Pharmacy
- Shanghai Jiao Tong University
- Shanghai 200240
- China
| | - Ende He
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs
- School of Pharmacy
- Shanghai Jiao Tong University
- Shanghai 200240
- China
| | - Lu Zhang
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs
- School of Pharmacy
- Shanghai Jiao Tong University
- Shanghai 200240
- China
| | - Jianzhong Chen
- School of Chemistry and Chemical Engineering
- Shanghai Jiao Tong University
- Shanghai 200240
- China
| | - Zhenfeng Zhang
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs
- School of Pharmacy
- Shanghai Jiao Tong University
- Shanghai 200240
- China
| | - Yangang Liu
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs
- School of Pharmacy
- Shanghai Jiao Tong University
- Shanghai 200240
- China
| | - Wanbin Zhang
- Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs
- School of Pharmacy
- Shanghai Jiao Tong University
- Shanghai 200240
- China
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27
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Zhang CL, Zhang ZF, Xia ZH, Han YF, Ye S. DBU-Mediated Construction of 1,3,5-Trisubstituted Benzenes via Annulation of α,β-Unsaturated Carboxylic Acids and α-Cyano-β-methylenones. J Org Chem 2018; 83:12507-12513. [PMID: 30247035 DOI: 10.1021/acs.joc.8b01740] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A DBU-mediated synthesis of 1,3,5-trisubstituted benzenes was developed via the [2 + 4] annulation of in situ activated α,β-unsaturated carboxylic acids and α-cyano-β-methylenones. The dual role of DBU as Brønsted base and nucleophilic Lewis base is the key for the success of the reaction.
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Affiliation(s)
- Chun-Lin Zhang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China
| | - Zhao-Fei Zhang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China.,University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Zi-Hao Xia
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China.,University of Chinese Academy of Sciences , Beijing 100049 , China
| | - You-Feng Han
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China.,University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Song Ye
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China.,University of Chinese Academy of Sciences , Beijing 100049 , China
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28
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Greenhalgh MD, Qu S, Slawin AMZ, Smith AD. Multiple roles of aryloxide leaving groups in enantioselective annulations employing α,β-unsaturated acyl ammonium catalysis. Chem Sci 2018; 9:4909-4918. [PMID: 29910944 PMCID: PMC5982221 DOI: 10.1039/c8sc01324a] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/04/2018] [Indexed: 12/13/2022] Open
Abstract
An isothiourea-catalysed Michael addition-annulation process using β-fluoroalkyl-substituted α,β-unsaturated aryl esters and a range of 2-acylbenzazoles is reported for the enantioselective synthesis of dihydropyranone and dihydropyridinone products bearing polyfluorinated stereocenters (29 examples, up to 98% yield, >99 : 1 er). The choice of aryl group of the aryl ester proved essential in determining reaction enantioselectivity and dihydropyranone : dihydropyridinone product selectivity. The aryloxide leaving group is shown to play a number of essential additional roles, operating (i) as a Brønsted base, circumventing the need for an auxiliary base; and (ii) as a Lewis base to catalyse the isomerisation of dihydropyranone products into thermodynamically-favoured dihydropyridinones. After optimisation, this isomerisation process was exploited for the selective synthesis of dihydropyridinone products using acylbenzothiazoles, and either dihydropyranone or dihydropyridinone products using acylbenzoxazoles. Finally, the phenol derivative, produced following protonation of the aryloxide, is proposed to act as a Brønsted acid, which promotes an isothiourea-catalysed kinetic resolution of benzoxazole-derived dihydropyranones.
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Affiliation(s)
- Mark D Greenhalgh
- EaStCHEM , School of Chemistry , University of St Andrews , North Haugh , St Andrews KY16 9ST , UK .
| | - Shen Qu
- EaStCHEM , School of Chemistry , University of St Andrews , North Haugh , St Andrews KY16 9ST , UK .
| | - Alexandra M Z Slawin
- EaStCHEM , School of Chemistry , University of St Andrews , North Haugh , St Andrews KY16 9ST , UK .
| | - Andrew D Smith
- EaStCHEM , School of Chemistry , University of St Andrews , North Haugh , St Andrews KY16 9ST , UK .
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29
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Li X, Tang M, Wang Y, Wang Y, Li Z, Qu LB, Wei D. Insights into the N-Heterocyclic Carbene (NHC)-Catalyzed Intramolecular Cyclization of Aldimines: General Mechanism and Role of Catalyst. Chem Asian J 2018; 13:1710-1718. [PMID: 29667337 DOI: 10.1002/asia.201800313] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/02/2018] [Indexed: 12/14/2022]
Abstract
One of the most challenging questions in the Lewis base organocatalyst field is how to predict the most electrophilic carbon for the complexation of N-heterocyclic carbene (NHC) and reactant. This study provides a valuable case for this issue. Multiple mechanisms (A, B, C, D, and E) for the intramolecular cyclization of aldimine catalyzed by NHC were investigated by using density functional theory (DFT). The computed results reveal that the NHC energetically prefers attacking the iminyl carbon (AIC mode, which is associated with mechanisms A and C) rather than attacking the olefin carbon (AOC mode, which is associated with mechanisms B and D) or attacking the carbonyl carbon (ACC mode, which is associated with mechanism E) of aldimine. The calculated results based on the different reaction models indicate that mechanism A (AIC mode), which is associated with the formation of the aza-Breslow intermediate, is the most favorable pathway. For mechanism A, there are five steps: (1) nucleophilic addition of NHC to the iminyl carbon of aldimine; (2) [1,2]-proton transfer to form an aza-Breslow intermediate; (3) intramolecular cyclization; (4) the other [1,2]-proton transfer; and (5) regeneration of NHC. The analyses of reactivity indexes have been applied to explain the chemoselectivity, and the general principles regarding the possible mechanisms would be useful for the rational design of NHC-catalyzed chemoselective reactions.
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Affiliation(s)
- Xue Li
- The College of Chemistry and Molecular Engineering, Zhengzhou University, No. 100 Kexue Street, Zhengzhou, Henan, 450001, P. R. China
| | - Mingsheng Tang
- The College of Chemistry and Molecular Engineering, Zhengzhou University, No. 100 Kexue Street, Zhengzhou, Henan, 450001, P. R. China
| | - Yanyan Wang
- The College of Chemistry and Molecular Engineering, Zhengzhou University, No. 100 Kexue Street, Zhengzhou, Henan, 450001, P. R. China
| | - Yang Wang
- Department of Material and Chemical Engineering, Zhengzhou University of Light Industry, No. 100 Kexue Street, Zhengzhou, Henan, 450002, P. R. China
| | - Zhongjun Li
- The College of Chemistry and Molecular Engineering, Zhengzhou University, No. 100 Kexue Street, Zhengzhou, Henan, 450001, P. R. China
| | - Ling-Bo Qu
- The College of Chemistry and Molecular Engineering, Zhengzhou University, No. 100 Kexue Street, Zhengzhou, Henan, 450001, P. R. China
| | - Donghui Wei
- The College of Chemistry and Molecular Engineering, Zhengzhou University, No. 100 Kexue Street, Zhengzhou, Henan, 450001, P. R. China
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30
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Kang G, Yamagami M, Vellalath S, Romo D. Enantioselective Synthesis of Medium‐Sized Lactams via Chiral α,β‐Unsaturated Acylammonium Salts. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201802483] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Guowei Kang
- Department of Chemistry and Biochemistry Baylor University One Bear Place #97348 Waco TX 76798-7348 USA
| | - Masaki Yamagami
- Biomolecular Chemistry Laboratory Department of Chemistry Graduate School of Science 1-1 Machikaneyama, Toyonaka Osaka 560-0043 Japan
| | - Sreekumar Vellalath
- Department of Chemistry and Biochemistry Baylor University One Bear Place #97348 Waco TX 76798-7348 USA
| | - Daniel Romo
- Department of Chemistry and Biochemistry Baylor University One Bear Place #97348 Waco TX 76798-7348 USA
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31
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Kang G, Yamagami M, Vellalath S, Romo D. Enantioselective Synthesis of Medium-Sized Lactams via Chiral α,β-Unsaturated Acylammonium Salts. Angew Chem Int Ed Engl 2018; 57:6527-6531. [PMID: 29624841 DOI: 10.1002/anie.201802483] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Indexed: 11/12/2022]
Abstract
Medium-sized lactams are important structural motifs found in a variety of bioactive compounds and natural products but are challenging to prepare, especially in optically active form. A Michael addition/proton transfer/lactamization organocascade process is described that delivers medium-sized lactams, including azepanones, benzazepinones, azocanones, and benzazocinones, in high enantiopurity through the intermediacy of chiral α,β-unsaturated acylammonium salts. An unexpected indoline synthesis was also uncovered, and the benzazocinone skeleton was transformed into other complex heterocyclic derivatives, including spiroglutarimides, isoquinolinones, and δ-lactones.
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Affiliation(s)
- Guowei Kang
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798-7348, USA
| | - Masaki Yamagami
- Biomolecular Chemistry Laboratory, Department of Chemistry, Graduate School of Science, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Sreekumar Vellalath
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798-7348, USA
| | - Daniel Romo
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798-7348, USA
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32
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Abbasov ME, Hudson BM, Kong W, Tantillo DJ, Romo D. Enantioselective Diels-Alder-lactamization organocascades employing a furan-based diene. Org Biomol Chem 2018; 15:3179-3183. [PMID: 28358148 DOI: 10.1039/c6ob02738e] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
α,β-Unsaturated acylammonium salts are useful dienophiles enabling highly enantioselective and stereodivergent Diels-Alder-initiated organocascades with furan-based dienes. Complex polycyclic systems can thus be obtained from readily prepared dienes, commodity acid chlorides, and a chiral isothiourea organocatalyst under mild conditions. We describe the use of furan-based dienes bearing pendant sulfonamides leading to the generation of oxa-bridged, trans-fused tricyclic γ-lactams. This process constitutes the first highly enantio- and diastereoselective, organocatalytic Diels-Alder cycloadditions with these typically problematic dienes due to their reversibility. Computational studies suggest that the high diastereoselectivity with these furan dienes may be due to a reversible Diels-Alder cycloaddition for the endo adducts. In addition, the utility of this methodology is demonstrated through a concise approach to a core structure with similarity to the natural product isatisine A and a nonpeptidyl ghrelin-receptor inverse agonist.
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Affiliation(s)
- Mikail E Abbasov
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place 97348, Waco, Texas 76798, USA.
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33
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Van KN, Romo D. Multicomponent, Enantioselective Michael-Michael-Aldol-β-Lactonizations Delivering Complex β-Lactones. J Org Chem 2018; 83:632-643. [PMID: 29219311 DOI: 10.1021/acs.joc.7b02543] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Optically active, tertiary amine Lewis bases react with unsaturated acid chlorides to deliver chiral, α,β-unsaturated acylammonium salts. These intermediates participate in a catalytic, enantioselective, three-component process delivering bi- and tricyclic β-lactones through a Michael-Michael-aldol-β-lactonization. In a single operation, the described multicomponent, organocascade process forms complex bi- and tricyclic β-lactones by generating four new bonds, two rings, and up to four contiguous stereocenters. In the racemic series, yields of 22-75% were achieved using 4-pyrrolidinopyridine as Lewis base. In the enantioselective series employing isothiourea catalysts, a kinetic resolution of the initially formed racemic Michael adduct appears operative, providing yields of 46% to quantitative (based on 50% max) with up to 94:6 er. Some evidence for a dynamic kinetic asymmetric transformation for tricyclic-β-lactone 1d was obtained following optimization (yields up to 61%, 94:6 er) through a presumed reversible Michael.
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Affiliation(s)
- Khoi N Van
- Department of Chemistry, Texas A&M University , College Station, Texas 77842, United States
| | - Daniel Romo
- Department of Chemistry & Biochemistry, Baylor University , Waco, Texas 76798, United States
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34
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Kong W, Romo D. Diastereo- and Enantioselective Synthesis of Bi- and Tricyclic N-Heterocycle-Fused β-Lactones. J Org Chem 2017; 82:13161-13170. [DOI: 10.1021/acs.joc.7b02235] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Weixu Kong
- Department of Chemistry & Biochemistry, Baylor University, Waco, Texas 76710, United States
| | - Daniel Romo
- Department of Chemistry & Biochemistry, Baylor University, Waco, Texas 76710, United States
- Department of Chemistry, Texas A&M University, College Station, Texas 77840, United States
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35
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Matviitsuk A, Greenhalgh MD, Antúnez DB, Slawin AMZ, Smith AD. Aryloxide-Facilitated Catalyst Turnover in Enantioselective α,β-Unsaturated Acyl Ammonium Catalysis. Angew Chem Int Ed Engl 2017; 56:12282-12287. [PMID: 28791763 PMCID: PMC5638104 DOI: 10.1002/anie.201706402] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Indexed: 11/27/2022]
Abstract
A new general concept for α,β-unsaturated acyl ammonium catalysis is reported that uses p-nitrophenoxide release from an α,β-unsaturated p-nitrophenyl ester substrate to facilitate catalyst turnover. This method was used for the enantioselective isothiourea-catalyzed Michael addition of nitroalkanes to α,β-unsaturated p-nitrophenyl esters in generally good yield and with excellent enantioselectivity (27 examples, up to 79 % yield, 99:1 er). Mechanistic studies identified rapid and reversible catalyst acylation by the α,β-unsaturated p-nitrophenyl ester, and a recently reported variable-time normalization kinetic analysis method was used to delineate the complex reaction kinetics.
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Affiliation(s)
- Anastassia Matviitsuk
- EaStCHEMSchool of ChemistryUniversity of St AndrewsNorth HaughSt AndrewsFifeKY16 9STUK
| | - Mark D. Greenhalgh
- EaStCHEMSchool of ChemistryUniversity of St AndrewsNorth HaughSt AndrewsFifeKY16 9STUK
| | | | | | - Andrew D. Smith
- EaStCHEMSchool of ChemistryUniversity of St AndrewsNorth HaughSt AndrewsFifeKY16 9STUK
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36
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Matviitsuk A, Greenhalgh MD, Antúnez DJB, Slawin AMZ, Smith AD. Aryloxide-Facilitated Catalyst Turnover in Enantioselective α,β-Unsaturated Acyl Ammonium Catalysis. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201706402] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Anastassia Matviitsuk
- EaStCHEM; School of Chemistry; University of St Andrews; North Haugh St Andrews Fife KY16 9ST UK
| | - Mark D. Greenhalgh
- EaStCHEM; School of Chemistry; University of St Andrews; North Haugh St Andrews Fife KY16 9ST UK
| | | | - Alexandra M. Z. Slawin
- EaStCHEM; School of Chemistry; University of St Andrews; North Haugh St Andrews Fife KY16 9ST UK
| | - Andrew D. Smith
- EaStCHEM; School of Chemistry; University of St Andrews; North Haugh St Andrews Fife KY16 9ST UK
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