Exploiting the imidazolium effect in base-free ammonium enolate generation: synthetic and mechanistic studies

Claire M. Young; Daniel G. Stark; Thomas H. West; James E. Taylor; Andrew D. Smith

doi:10.1002/anie.201608046

Exploiting the imidazolium effect in base-free ammonium enolate generation: synthetic and mechanistic studies

Claire M. Young, Daniel G. Stark, Thomas H. West, James E. Taylor, Andrew D. Smith

Research output: Contribution to journal › Article › peer-review

Abstract

N-Acyl imidazoles and catalytic isothiourea hydrochloride salts function as ammonium enolate precursors in the absence of base. Enantioselective Michael addition-cyclization reactions using different α,β-unsaturated Michael acceptors have been performed to form dihydropyranones and dihydropyridinones with high stereoselectivity. Detailed mechanistic studies using RPKA have revealed the importance of the “imidazolium” effect in ammonium enolate formation and have highlighted key differences with traditional base-mediated processes.

Original language	English
Pages (from-to)	14394-14399
Number of pages	6
Journal	Angewandte Chemie International Edition
Volume	55
Issue number	46
Early online date	20 Oct 2016
DOIs	https://doi.org/10.1002/anie.201608046
Publication status	Published - 7 Nov 2016

Keywords

Imidazolium effect
Isothiourea catalysis
Mechanistic study
Michael addition
N-acyl imidazoles

Access to Document

10.1002/anie.201608046

Smith_2016_ACIE_Exploiting_AAM
Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1002/anie.201608046
Accepted author manuscript, 1.3 MB

ERC Starting Grant EnolCat: Emulating nature: Reaction diversity and understanding through asymmetric catalysis
Smith, A. D. (PI)
European Commission
1/10/11 → 30/06/17
Project: Standard

Andrew David Smith
- ads10st-andrews.acuk
- School of Chemistry - Professor, Director of Research
- Biomedical Sciences Research Complex
- EaSTCHEM
Person: Academic

Data underpinning "Exploiting the Imidazolium Effect in Base-free Ammonium Enolate Generation: Synthetic and Mechanistic Studies"
Smith, A. D. (Creator), Young, C. M. (Contributor), Stark, D. G. (Contributor), West, T. H. (Contributor) & Taylor, J. E. (Contributor), University of St Andrews, 17 Aug 2016
DOI: 10.17630/346a5fe8-a636-46e8-9933-71db82f0083a
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Cite this

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title = "Exploiting the imidazolium effect in base-free ammonium enolate generation: synthetic and mechanistic studies",

abstract = "N-Acyl imidazoles and catalytic isothiourea hydrochloride salts function as ammonium enolate precursors in the absence of base. Enantioselective Michael addition-cyclization reactions using different α,β-unsaturated Michael acceptors have been performed to form dihydropyranones and dihydropyridinones with high stereoselectivity. Detailed mechanistic studies using RPKA have revealed the importance of the “imidazolium” effect in ammonium enolate formation and have highlighted key differences with traditional base-mediated processes.",

keywords = "Imidazolium effect, Isothiourea catalysis, Mechanistic study , Michael addition, N-acyl imidazoles",

author = "Young, {Claire M.} and Stark, {Daniel G.} and West, {Thomas H.} and Taylor, {James E.} and Smith, {Andrew D.}",

note = "The authors thank the European Research Council under the European Union{\textquoteright}s Seventh Framework Programme (FP7/2007-2013) ERC Grant Agreement no. 279850 (CMY, THW, JET). ADS thanks the Royal Society for a Wolfson Merit Award.",

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doi = "10.1002/anie.201608046",

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T1 - Exploiting the imidazolium effect in base-free ammonium enolate generation

T2 - synthetic and mechanistic studies

AU - Young, Claire M.

AU - Stark, Daniel G.

AU - West, Thomas H.

AU - Taylor, James E.

AU - Smith, Andrew D.

N1 - The authors thank the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) ERC Grant Agreement no. 279850 (CMY, THW, JET). ADS thanks the Royal Society for a Wolfson Merit Award.

PY - 2016/11/7

Y1 - 2016/11/7

N2 - N-Acyl imidazoles and catalytic isothiourea hydrochloride salts function as ammonium enolate precursors in the absence of base. Enantioselective Michael addition-cyclization reactions using different α,β-unsaturated Michael acceptors have been performed to form dihydropyranones and dihydropyridinones with high stereoselectivity. Detailed mechanistic studies using RPKA have revealed the importance of the “imidazolium” effect in ammonium enolate formation and have highlighted key differences with traditional base-mediated processes.

AB - N-Acyl imidazoles and catalytic isothiourea hydrochloride salts function as ammonium enolate precursors in the absence of base. Enantioselective Michael addition-cyclization reactions using different α,β-unsaturated Michael acceptors have been performed to form dihydropyranones and dihydropyridinones with high stereoselectivity. Detailed mechanistic studies using RPKA have revealed the importance of the “imidazolium” effect in ammonium enolate formation and have highlighted key differences with traditional base-mediated processes.

KW - Imidazolium effect

KW - Isothiourea catalysis

KW - Mechanistic study

KW - Michael addition

KW - N-acyl imidazoles

U2 - 10.1002/anie.201608046

DO - 10.1002/anie.201608046

M3 - Article

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VL - 55

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EP - 14399

JO - Angewandte Chemie International Edition

JF - Angewandte Chemie International Edition

IS - 46

ER -

Exploiting the imidazolium effect in base-free ammonium enolate generation: synthetic and mechanistic studies

Abstract

Keywords

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Projects

ERC Starting Grant EnolCat: Emulating nature: Reaction diversity and understanding through asymmetric catalysis

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Andrew David Smith

Datasets

Data underpinning "Exploiting the Imidazolium Effect in Base-free Ammonium Enolate Generation: Synthetic and Mechanistic Studies"

Cite this