Asymmetric Michael addition reactions catalyzed by calix[4]thiourea cyclohexanediamine derivatives
作者:Zheng-Yi Li、Hong-Xiao Tong、Yuan Chen、Hong-Kui Su、Tangxin Xiao、Xiao-Qiang Sun、Leyong Wang
DOI:10.3762/bjoc.14.164
日期:——
rim-functionalized calix[4]thiourea cyclohexanediamine derivatives have been designed, synthesized and used as catalysts for enantioselective Michael addition reactions between nitroolefins and acetylacetone. The optimal catalyst 2 with a mono-thiourea group exhibited good performance in the presence of water/toluene (v/v = 1:2). Under the optimal reaction conditions, high yields of up to 99% and moderate
efficient method was developed to synthesize ferrocene-based bifunctionalamine–thioureasbearingmultiplehydrogen-bondingdonors. Asymmetric Michaeladdition of acetylacetone to nitroolefins catalyzed by these novel bifunctionalcatalysts affords the Michael adducts in high yield and moderate to excellent enantioselectivities. Multiplehydrogen-bonds play an important role in accelerating the reaction.
Novel bifunctional chiral thiourea-tertiary amines bearing a calix[4]arene scaffold were synthesized and applied in catalytic asymmetric Michael addition of acetyl acetone and dimethyl malonate to nitroolefins. The corresponding adducts were obtained in excellent yields (up to 99%) and with high enantioselectivities (up to 94% ee). (C) 2016 Elsevier Ltd. All rights reserved.