Preparation of Functionalized Dialkylzincs via a Boron-Zinc Exchange. Reactivity and Catalytic Asymmetric Addition to Aldehydes.

The hydroboration of olefins with Et(2)BH provides diethyl(alkyl)boranes 2 which readily undergo a boron-zinc exchange with Et(2)Zn providing a range of polyfunctional primary, secondary, and benzylic diorganozincs. The resulting diorganozincs 3 have been reacted with various electrophiles (allylic halides, acid chlorides, alkylidenemalonates, ethyl propiolate, nitroolefins) in the presence of CuCN.2LiCl with excellent yields.