Diaminomethylenemalononitrile organocatalyst 5 promotes the asymmetric conjugate addition of branched aldehydes to vinyl sulfone to afford the corresponding adducts with all-carbon quaternary stereocenters in excellent yields with up to 91% ee.
Chiral primary amine mediated conjugate addition of branched aldehydes to vinyl sulfone: asymmetric generation of quaternary carbon centers
作者:Qiang Zhu、Yixin Lu
DOI:10.1039/b919549a
日期:——
Novel L-threonine-derived bifunctional organic catalysts containing primary amine and sulfonamide groups were utilized to promote asymmetric conjugateaddition of alpha,alpha-disubstituted aldehydes to 1,1-bis(benzenesulfonyl)ethylene. The adducts with quaternary stereogenic centers adjacent to an aldehyde group were obtained in high yield and with good enantioselectivity.
Chiral framework: Chiral amines with pyrrolidine frameworks catalyze the enantioselective conjugate addition of a wide range of aldehydes to various vinyl sulfones and vinyl phosphonates in high yields and with enantioselectivities up to >99 % ee (see scheme). The high versatility of the Michael adducts is exemplified by various functionalizations with conservation of the optical purity.