Highly diastereoselective allylation of lactols and their ethers using molecular iodine

Lactols and their ethers undergo smooth allylation with allyltrimethylsilane in the presence of 5 mol % iodine in dichloromethane at -78 degrees C to afford C-allylfuranosides in good yields and with high diastereoselectivity. The use of iodine makes this method simple, convenient and practical. This is the first report on the allylation of lactols with allyltrimethylsilane using molecular iodine as a catalyst. Enhanced diastereoselectivity is the key feature of this protocol. (C) 2009 Elsevier Ltd. All rights reserved.