diastereoselective chloroallylboration of α-chiral aldehydes.

Double asymmetric reaction of chiral (Z)-(γ-chloroallyl)borane, 2, with α-chiral aldehydes (3−7) provide a new practical method for the generation of 2,3-syn-3,4-anti and 2,3-syn-3,4-syn chiral vinylchlorohydrins (8−17) and vinyl epoxides (18−27). Both enantiomers of 2 exhibited excellent diatereoselectivity (≥90 de) for matched cases. The mismatched cases yielded moderate to good diastereoselectivity.