A general, highly enantioselective Michael addition of nitroalkanes to α,β-unsaturated enones catalyzed by 9-amino(9-deoxy)-epi-quinine: a remarkable additive effect
作者:Siyang Liu、Qingqing Wang、Ling Ye、Zhichuan Shi、Zhigang Zhao、Xuejun Yang、Keyi Ding、Xuefeng Li
DOI:10.1016/j.tet.2016.07.008
日期:2016.8
A particularly general protocol for the organocatalytic asymmetric Michael addition of nitroalkanes to α,β-unsaturated enones is reported. The Michaelreaction proceeded smoothly and provided the desired adducts in moderate to excellent yields (55–99%) and good to excellent enantioselectivities (65–99% ee). The addition of readily available achiral base significantly enhanced the reactivity without
Effect of High Pressure on the Organocatalytic Asymmetric Michael Reaction: Highly Enantioselective Synthesis of γ-Nitroketones with Quaternary Stereogenic Centers
The significant effect of hydrostatic pressure on the difficult organocatalytic 1,4-conjugate addition of nitroalkanes to prochiral sterically congested beta,beta-disubstituted enones is demonstrated. This approach allows for the synthesis of gamma-nitroketones containing quaternary stereogenic centers with good yields, excellent enantioselectivity, and low loading (1-5 mol %) of simple chiral primary amine catalysts.