Aryloxide-facilitated catalyst turnover in enantioselective α,β-unsaturated acyl ammonium catalysis
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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.
Matviitsuk , A , Greenhalgh , M , Barrios Antunez , D , Slawin , A & Smith , A D 2017 , ' Aryloxide-facilitated catalyst turnover in enantioselective α,β-unsaturated acyl ammonium catalysis ' Angewandte Chemie International Edition , vol Early View . DOI: 10.1002/ange.201706402
Angewandte Chemie International Edition
© 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
The authors 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/J018139/1, A.M.) for funding. A.D.S. thanks the Royal Society for a Wolfson Research Merit Award.
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