Preparation of New Polyfunctional Diorganozincs Using a Boron-Zinc Exchange Reaction

F. Langer; A. Devasagayaraj; P.-Y. Chavant; P. Knochel

doi:10.1055/s-1994-22868

Synlett 1994; 1994(6): 410-412
DOI: 10.1055/s-1994-22868

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Preparation of New Polyfunctional Diorganozincs Using a Boron-Zinc Exchange Reaction

F. Langer^* , A. Devasagayaraj, P. -Y. Chavant, P. Knochel

^*Fachbereich Chemie der Philipps-Universität Marburg, D-35032 Marburg (Germany)

Abstract

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The hydroboration of polyfunctional olefins with Et₂BH prepared from commercially available Et₃B and BH₃·SMe₂, followed by a treatment with neat Et₂Zn (2 equiv) produces a range of new polyfunctional diorganozincs, some of which cannot be prepared by known methods. After transmetalation with CuCN·2 LiCl and addition of an electrophile (acid chloride, enone, nitro olefin, ethyl propiolate or allylic bromide), various polyfunctional products are obtained in 60-83 % overall yield (based on the olefin). The zinc reagents prepared in this way can also be used for the catalytic enantioselective addition to aldehydes (90-95 % ee).

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