Enantioselective Michael Addition of Dicyanoolefins to α,β-Unsaturated Aldehydes in Aqueous Medium
作者:Jun Lu、Feng Liu、Teck-Peng Loh
DOI:10.1002/adsc.200800145
日期:2008.8.4
A pool of water-compatible catalysts, namely dialkyl-(S)-prolinols, has been developed for the enantioselective directvinylogousMichaeladdition reaction of vinylmalononitriles to α,β-unsaturatedaldehydes in aqueous medium. In many cases, the products can be obtained in almost optically pure form (>96% ee) after a single recrystallization.
Enantioselective direct vinylogous Michael addition reaction catalyzed by organic molecules
作者:Jun Lu、Feng Liu、Wei-Juan Zhou、Teck-Peng Loh
DOI:10.1016/j.tetlet.2008.07.016
日期:2008.9
Chiral 2-azanorbornyl-3-methanol is used as an organocatalyst for the highly enantioselective directvinylogousMichaeladdition reaction of vinyl malononitriles to α,β-unsaturatedaldehydes. In many cases, the products can be obtained in almost optically pure form (>95% ee) after a single recrystallization.
King of the ring: S‐(trifluoromethyl)benzo[b]thiophenium salts 1, as analogues of Yagupolskii–Umemoto type reagents, were synthesized by novel triflicacidcatalyzedintramolecularcyclization of ortho‐ethynylaryltrifluoromethylsulfanes 2. 1 j is especially useful for the electrophilic trifluoromethylation of β‐ketoesters and dicyanoalkylidenes.
yield (up to 98%) and high enantioselectivity (up to 97% ee) via vinylogous Michaelreaction/cyclization cascadereaction of α‐arylidene pyrazolones and α,α‐dicyanoalkylidenes. The formal [4+2] atom‐economical annulation proceeds with commercially available Takemoto's catalyst under mild reaction conditions. Scale‐up reaction and post‐transformation of the products were also demonstrated.
Organocatalytic and direct asymmetric vinylogous Michael addition of α,α-dicyanoolefins to α,β-unsaturated aldehydes
作者:Jian-Wu Xie、Lei Yue、Dong Xue、Xiao-Li Ma、Ying-Chun Chen、Yong Wu、Jin Zhu、Jin-Gen Deng
DOI:10.1039/b600647g
日期:——
The first highly regio-, chemo-, diastereo- and enantioselectivedirectvinylogousMichaeladdition of alpha,alpha-dicyanoolefins to alpha,beta-unsaturated aldehydes is described, employing readily available chiral alpha,alpha-diarylprolinol salts as iminium organocatalysts.