Base-free enantioselective C(1)-ammonium enolate catalysis exploiting aryloxides : a synthetic and mechanistic study
Date
14/10/2019Keywords
Metadata
Show full item recordAltmetrics Handle Statistics
Altmetrics DOI Statistics
Abstract
An isothiourea‐catalyzed enantioselective Michael addition of aryl ester pronucleophiles to vinyl bis‐sulfones via C(1)‐ammonium enolate intermediates has been developed. This operationally simple method allows the base‐free functionalization of aryl esters to form α‐functionalized products containing two contiguous tertiary stereogenic centres in excellent yield and stereoselectivity (all ≥ 99:1 er). Key to the success of this methodology is the multifunctional role of the aryloxide, which operates as a leaving group, Brønsted base, Brønsted acid and Lewis base within the catalytic cycle. Comprehensive mechanistic studies, including variable time normalization analysis (VTNA) and isotopologue competition experiments, have been carried out. These studies have identified (i) orders of all reactants; (ii) a turnover‐limiting Michael addition step, (iii) product inhibition, (iv) the catalyst resting state and (v) catalyst deactivation through protonation.
Citation
McLaughlin , C , Slawin , A M Z & Smith , A D 2019 , ' Base-free enantioselective C(1)-ammonium enolate catalysis exploiting aryloxides : a synthetic and mechanistic study ' , Angewandte Chemie International Edition , vol. 58 , no. 42 , pp. 15111-15119 . https://doi.org/10.1002/anie.201908627
Publication
Angewandte Chemie International Edition
Status
Peer reviewed
ISSN
1433-7851Type
Journal article
Rights
Copyright © 2019 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted 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.201908627
Description
We thank the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013) ERC grant agreement no. 279850 (A.D.S) and the EPSRC (EP/M508214/1, C.M.) for funding. A.D.S. thanks the Royal Society for a Wolfson Research Merit Award.Collections
Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.