Asymmetric Synthesis of Spirocyclic Oxindole-Fused Tetrahydrothiophenes via N,N '-Dioxide-Nickel(II) Catalyzed Domino Reaction of 1,4-Dithiane-2,5-diol with 3-Alkenyloxindoles

摘要

A highly efficient chiral N,N'-dioxidenickel(II) complex system has been developed to catalyze the domino thia-Michael/aldol reaction of 1,4-dithiane-2,5-diol with 3-alkenyloxindoles. A series of the desired spirocyclic oxindole-fused tet-rahydrothiophenes was obtained in good yields with excellent ee and dr (up to 97% yield, 98% ee, >19: 1 dr). Besides, based on the X-ray crystal structure of the catalyst as well as the absolute configuration of the product, a catalytic model was proposed to explain the stereocontrol process.