Organocatalytic stereoselective conjugate addition of 3-substituted oxindoles with in situ generated ortho-quinone methides
作者:Weihong Liang、Wenhao Yin、Tingzhong Wang、Fayang G. Qiu、Junling Zhao
DOI:10.1016/j.tetlet.2018.03.069
日期:2018.5
A novel method for the stereoselectiveconjugateaddition of 3-substituted oxindoles to in situ generated o-QMs was described. This process was catalyzed efficiently by a cinchonidine-derived squaramide catalyst in oil-water phase, furnishing the corresponding 3,3-disubsituted oxindole derivatives in moderate to high yields (up to 98%) with high stereoselectivities (up to 95% ee, 15.4:1 dr). The utility
Bifunctional Amine-Squaramide Catalyzed Friedel-Crafts Alkylation Based on<i>ortho</i>-Quinone Methides in Oil-Water Phases: Enantioselective Synthesis of Triarylmethanes
An efficient enantioselective Friedel–Crafts alkylation reaction of electron‐rich β‐naphthol with in situ generated ortho‐quinone methides catalyzed by chiral bifunctional amine‐squaramide catalysts has been developed. The chiral triarylmethane derivatives were obtained in good to high yields (up to 97% yield) with high enantioselectivities (up to 97% ee) for most substrates under mild conditions.
An asymmetric conjugate addition of thiocarboxylicacids to in situ‐generated ortho‐quinomethanes (o‐QMs) catalyzed by bifunctional squaramide catalysts has been developed. The transformation proceeds with high yields (up to 96%) and enantioselectivities (up to 96% ee) in the oil‐water phases. The resulting thioester could be converted facilely into the chiral benzyl mercaptan in high yield without
Organocatalytic asymmetric conjugate addition of t-butyl nitroacetate to o-quinone methides: synthesis of optically active α-nitro-β,β-diaryl-propionates
作者:Ri-long Liu、Xiang-zheng Tang、Xue-jing Zhang、Ming Yan、Albert S. C. Chan
DOI:10.1039/c6ra28068d
日期:——
An asymmetric conjugate addition of t-butyl nitroacetate to in situ generated o-quinone methides had been developed. A chiral squamide derived from 9-amino-9-deoxyepiquinine was found to be the efficient catalyst. α-Nitro-β,β-diaryl-propionates could be obtained in good yields and with excellent enantioselectivities.