A versatile organocatalyst for the asymmetric conjugate addition of nitroalkanes to enones
作者:Claire E. T. Mitchell、Stacey E. Brenner、Steven V. Ley
DOI:10.1039/b511441a
日期:——
5-Pyrrolidin-2-yltetrazole performs as an improved catalyst for the asymmetricaddition of a range of nitroalkanes to cyclic and acyclic enones, with good to excellent enantioselectivity.
An efficient, asymmetric organocatalyst-mediated conjugate addition of nitroalkanes to unsaturated cyclic and acyclic ketones
作者:Claire E. T. Mitchell、Stacey E. Brenner、Jorge García-Fortanet、Steven V. Ley
DOI:10.1039/b601877g
日期:——
5-Pyrrolidin-2-yltetrazole is a versatile organocatalyst for the asymmetric conjugateaddition of nitroalkanes to enones. Using this catalyst, this transformation requires short reaction times, tolerates a broad substrate scope, and possibly proceeds via generation of an iminium species.
Chiral diethyl (2R)-tetrahydropyrro-2-ylphosphonate is an effective catalyst for the Michael addition of nitroalkanes to alpha,beta-unsaturated ketones. This Study revealed that the hydrate salt of this alpha-aminophosphonate was found to be a better catalytic species. Moderate to high enantioselectivities were achieved in reactions that tolerate various nitroalkanes and enones in the presence of low loading of both catalyst ( 10 mol %) and bulk base (25 mol %). (C) 2008 Published by Elsevier Ltd.
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.
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