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Aryloxide-Facilitated Catalyst Turnover in Enantioselective ?,?-Unsaturated Acyl Ammonium Catalysis.

ABSTRACT: A new general concept for ?,?-unsaturated acyl ammonium catalysis is reported that uses p-nitrophenoxide release from an ?,?-unsaturated p-nitrophenyl ester substrate to facilitate catalyst turnover. This method was used for the enantioselective isothiourea-catalyzed Michael addition of nitroalkanes to ?,?-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 ?,?-unsaturated p-nitrophenyl ester, and a recently reported variable-time normalization kinetic analysis method was used to delineate the complex reaction kinetics.

SUBMITTER: Matviitsuk A

PROVIDER: S-EPMC5638104 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Aryloxide-Facilitated Catalyst Turnover in Enantioselective α,β-Unsaturated Acyl Ammonium Catalysis.

Matviitsuk Anastassia A Greenhalgh Mark D MD Antúnez Diego-Javier Barrios DB Slawin Alexandra M Z AMZ Smith Andrew D AD

Angewandte Chemie (International ed. in English) 20170825 40

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 cat ...[more]

PMID: 28791763

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