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Remmerswaal WA, Hansen T, Hamlin TA, Codée JDC. Origin of Stereoselectivity in S E 2' Reactions of Six-membered Ring Oxocarbenium Ions. Chemistry 2023; 29:e202203490. [PMID: 36511875 DOI: 10.1002/chem.202203490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 12/15/2022]
Abstract
Oxocarbenium ions are key reactive intermediates in organic chemistry. To generate a series of structure-reactivity-stereoselectivity principles for these species, we herein investigated the bimolecular electrophilic substitution reactions (SE 2') between allyltrimethylsilane and a series of archetypal six-membered ring oxocarbenium ions using a combined density functional theory (DFT) and coupled-cluster theory approach. These reactions preferentially proceed following a reaction path where the oxocarbenium ion transforms from a half chair (3 H4 or 4 H3 ) to a chair conformation. The introduction of alkoxy substituents on six-membered ring oxocarbenium ions, dramatically influences the conformational preference of the canonical 3 H4 and 4 H3 conformers, and thereby the stereochemical outcome of the SE 2' reaction. In general, we find that the stereoselectivity in the reactions correlates to the "intrinsic preference" of the cations, as dictated by their shape. However, for the C5-CH2 OMe substituent, steric factors override the "intrinsic preference", showing a more selective reaction than expected based on the shape of the ion. Our SE 2' energetics correlate well with experimentally observed stereoselectivity, and the use of the activation strain model has enabled us to quantify important interactions and structural features that occur in the transition state of the reactions to precisely understand the relative energy barriers of the diastereotopic addition reactions. The fundamental mechanistic insight provided in this study will aid in understanding the reactivity of more complex glycosyl cations featuring multiple substituents and will facilitate our general understanding of glycosylation reactions.
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Affiliation(s)
- Wouter A Remmerswaal
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden (The, Netherlands
| | - Thomas Hansen
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden (The, Netherlands.,Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The, Netherlands
| | - Trevor A Hamlin
- Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The, Netherlands
| | - Jeroen D C Codée
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC, Leiden (The, Netherlands
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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van der Vorm S, Hansen T, van Rijssel ER, Dekkers R, Madern JM, Overkleeft HS, Filippov DV, van der Marel GA, Codée JDC. Furanosyl Oxocarbenium Ion Conformational Energy Landscape Maps as a Tool to Study the Glycosylation Stereoselectivity of 2-Azidofuranoses, 2-Fluorofuranoses and Methyl Furanosyl Uronates. Chemistry 2019; 25:7149-7157. [PMID: 30882938 PMCID: PMC6563709 DOI: 10.1002/chem.201900651] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 03/12/2019] [Indexed: 12/16/2022]
Abstract
The 3D shape of glycosyl oxocarbenium ions determines their stability and reactivity and the stereochemical course of SN 1 reactions taking place on these reactive intermediates is dictated by the conformation of these species. The nature and configuration of functional groups on the carbohydrate ring affect the stability of glycosyl oxocarbenium ions and control the overall shape of the cations. We herein map the stereoelectronic substituent effects of the C2-azide, C2-fluoride and C4-carboxylic acid ester on the stability and reactivity of the complete suite of diastereoisomeric furanoses by using a combined computational and experimental approach. Surprisingly, all furanosyl donors studied react in a highly stereoselective manner to provide the 1,2-cis products, except for the reactions in the xylose series. The 1,2-cis selectivity for the ribo-, arabino- and lyxo-configured furanosides can be traced back to the lowest-energy 3 E or E3 conformers of the intermediate oxocarbenium ions. The lack of selectivity for the xylosyl donors is related to the occurrence of oxocarbenium ions adopting other conformations.
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Abstract
The combination of -I and -M effects and the aromaticity of the conjugate base renders the chiral pentacarboxy-substituted cyclopentadienes (PCCPs) acidic. Their convenient synthesis together with substrates derived from the chiral pool and their performance in the tested reactions renders them prodigious candidates to become a new and highly competitive class of chiral Brønsted acid catalysts.
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Affiliation(s)
- Ivana Fleischer
- Department of Organic Chemistry, University of Regensburg, Universitätsstrasse 31, 93040, Regensburg, Germany.
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Sabbatani J, Maulide N. Temporary Generation of a Cyclopropyl Oxocarbenium Ion Enables Highly Diastereoselective Donor-Acceptor Cyclopropane Cycloaddition. Angew Chem Int Ed Engl 2016; 55:6780-3. [PMID: 27099179 DOI: 10.1002/anie.201601340] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 03/07/2016] [Indexed: 11/08/2022]
Abstract
A novel formal [3+2] cycloaddition of cyclopropylacetals and aldehydes was developed, and the resulting trisubstituted tetrahydrofurans display three new chiral centers formed with highly diastereoselectivity. This method is stereocomplementary to most previously reported cycloadditions of malonate diesters, relies on the transient generation of cyclopropyl oxocarbenium ions, proceeds under mild conditions, and is based on the concept of temporary activation of an otherwise inert protecting group.
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Affiliation(s)
- Juliette Sabbatani
- Fakultät für Chemie, Institut für Organische Chemie, Universität Wien, Währinger Straße 38, 1090, Wien, Austria
| | - Nuno Maulide
- Fakultät für Chemie, Institut für Organische Chemie, Universität Wien, Währinger Straße 38, 1090, Wien, Austria.
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Fuwa H. Contemporary Strategies for the Synthesis of Tetrahydropyran Derivatives: Application to Total Synthesis of Neopeltolide, a Marine Macrolide Natural Product. Mar Drugs 2016; 14:E65. [PMID: 27023567 PMCID: PMC4849069 DOI: 10.3390/md14040065] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/15/2016] [Accepted: 03/17/2016] [Indexed: 02/07/2023] Open
Abstract
Tetrahydropyrans are structural motifs that are abundantly present in a range of biologically important marine natural products. As such, significant efforts have been paid to the development of efficient and versatile methods for the synthesis of tetrahydropyran derivatives. Neopeltolide, a potent antiproliferative marine natural product, has been an attractive target compound for synthetic chemists because of its complex structure comprised of a 14-membered macrolactone embedded with a tetrahydropyran ring, and twenty total and formal syntheses of this natural product have been reported so far. This review summarizes the total and formal syntheses of neopeltolide and its analogues, highlighting the synthetic strategies exploited for constructing the tetrahydropyran ring.
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Affiliation(s)
- Haruhiko Fuwa
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
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Abstract
Controlling enantioselectivity in additions to oxocarbenium ions remains a challenge in asymmetric catalysis. By catalytically generating a chiral organometallic intermediate, a copper acetylide, we have developed a novel approach for additions of carbon nucleophiles to cyclic oxocarbenium ions in high enantioselectivities and yields.
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Affiliation(s)
- Mary P Watson
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Prantik Maity
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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