Kinetic resolution of γ-iodo allylic alcohols by the Sharpless asymmetric epoxidation reaction proceeds with very large rate differences for the two enantiomers, thus providing a highly efficient method for preparation of optically pure . The alcohols thus prepared can be readily converted into various secondary allylic alcohols through the coupling reaction with nucleophiles.
In the presence of AIBN or Et3B, a variety of vinyl iodides reacted with allylstannanes bearing an electron-withdrawing group at the beta-position to afford 1,4-dienes in moderate to good yields. The allylation showed high stereoselectivity when the alpha-substituent of the iodides was a phenyl group, or the B-substituent was a bulky group. (C) 1999 Elsevier Science Ltd. All rights reserved.