Double asymmetric reaction of chiral (Z)-(gamma-chloroallyl)borane, 2, with
alpha-chiral aldehydes (3-7) provide a new practical method for the genera
tion of 2,3-syn-3,4-anti and 2,3-syn-3,4-syn chiral vinylchlorohydrins (8-1
7) and vinyl epoxides(18-27). Both enantiomers of 2 exhibited excellent dia
tereoselectivity (greater than or equal to 90 de) for matched cases. The mi
smatched cases yielded moderate to good diastereoselectivity.