キラルビニルスルホキシドを用いたニッケル触媒不斉環化反応の開発

抄録

Vinylic sulfoxides are a well-known chiral controller and applied to many asymmetric reactions. However, applications to transition metal-catalyzed reactions are limited. We have developed a novel Ni(0)-catalyzed asymmetric carbocyclization of enone to vinylic sulfoxide, in which carbon-carbon bond formation between these functional groups proceeded smoothly upon treatment with Et2Zn in the presence of Ni(0)-catalyst to give disubstituted cyclopentane compound. In contrast that the (E)-vinylic sulfoxide afforded cis-isomer, the (Z)-vinylic sulfoxide produced trans-isomer predominately. Diastereoselectivity of the reaction was influenced by solvent and additive. Both the yield and selectivity were improved when tolune was used as a solvent in the presence of three equivalents of MeCN. Addition of zinc bromide also afforded good results in the reaction of the (E)-vinylic sulfoxide.

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