EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK.
Angew Chem Int Ed Engl. 2017 Sep 25;56(40):12282-12287. doi: 10.1002/anie.201706402. Epub 2017 Aug 25.
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.
报道了一种新的α，β-不饱和酰基铵催化的一般概念，该概念利用从α，β-不饱和对硝基苯基酯底物中释放出对硝基苯酚盐来促进催化剂周转。该方法用于对硝基烷烃与α，β-不饱和对硝基苯基酯的手性异硫脲催化迈克尔加成反应，通常具有良好的收率和优异的对映选择性（27 个实例，最高收率为 79％，ee 值为 99：1）。机理研究确定了α，β-不饱和对硝基苯基酯对催化剂的快速和可逆酰化，并且使用了最近报道的变时归一化动力学分析方法来描绘复杂的反应动力学。
