Enantioselective conjugate addition of 1-bromonitroalkanes to α,β-unsaturated aldehydes catalyzed by chiral secondary amines
作者:Jun-min Zhang、Zhi-peng Hu、Li-ting Dong、Yi-ning Xuan、Chun-Liang Lou、Ming Yan
DOI:10.1016/j.tetasy.2009.01.003
日期:2009.2
Highly enantioselectiveconjugateaddition of bromonitromethane to α,β-unsaturatedaldehydescatalyzed by chiral secondary amines has been achieved. Diphenylprolinol triethylsilyl ether was found to be the best catalyst for the reaction under MeOH/AcONa system. Various β-aryl acroleins afforded nitrocyclopropanes with excellent enantioselectivities and in good yields; however, the reaction of β-alkyl
Organocatalytic conjugate addition of 1-bromonitroalkanes to α,β-unsaturated aldehydes: synthesis of nitrocyclopropanes
作者:Jun-min Zhang、Zhi-peng Hu、Shuang-qi Zhao、Ming Yan
DOI:10.1016/j.tet.2008.11.060
日期:2009.1
A variety of secondary amines were studied as the catalyst in the conjugate addition of 1-bromonitromethane to alpha,beta-unsaturated aldehydes. Proline was identified as the best catalyst for this reaction. MeOH/AcONa system was found to provide much better yields than CHCl3/Et3N system reported before. Good yields of nitrocyclopropane products were obtained with a variety of beta-aryl acroleins. Several substituted 1-bromonitrornethanes were also examined in the reaction. Both 1-bromonitroethane and 1-phenyl-1-bromonitromethane gave the corresponding nitrocyclopropanes in good yields. The diastereo-selectivity of the reaction was strongly affected by the steric hindrance of 1-bromonitroalkanes. (C) 2008 Elsevier Ltd. All rights reserved.
An Artificial Enzyme for Asymmetric Nitrocyclopropanation of α,β‐Unsaturated Aldehydes ‐ Design and Evolution
Generation of an artificial enzyme that features a secondary amine residue by genetic code expansion is described. The designer enzyme was evolved to catalyze the asymmetric nitrocyclopropanation of cinnamaldehydes at high conversions with excellent diastereo- and enantioselectivity.