Iodine as a mild and efficient catalyst for the diastereoselective synthesis of δ-silyloxy-γ-lactones

Aldehydes undergo smooth nucleophilic addition with 2-trimethylsilyloxyfuran in the presence of 10 mol % of iodine under mild and neutral conditions to produce the corresponding δ-silyloxy-α,β-unsaturated-γ-lactones in high yields and with moderate diastereoselectivity. ortho-Substituted benzaldehydes afford the syn-isomer predominantly. The use of iodine makes this procedure quite simple, more convenient and cost-effective.