Reduction of monothioacetals with SmI2: application to [2,3]-Wittig rearrangement

Simple reduction of ,S-acetals with SmI2 yielding ethers with selective lib eration of the sulfenyl group can be accomplished using benzene-HMPA with t -BuOH. When O,S-acetals possess an O-allyl group, the [2,3]-Wittig rearrang ement yielding homoallyl alcohols follows the elimination of a sulfenyl gro up. For chemoselective elimination of an alkoxy group to give sulfides, MeO Tf serves as a moderately effective additive. (C) 2001 Elsevier Science Ltd . All rights reserved.