STEREOSELECTIVE [2,3]-SIGMATROPIC WITTIG REARRANGEMENT OF BENZYL ETHERS DERIVED FROM VINYLCUPRATE ADDUCTS OF (R)-2,3-O-ISOPROPYLIDENEGLYCERALDEHYDE

Allyl alcohols 2 prepared by addition of lithium vinylcuprates to (R)-2,3-O-isopropylideneglyceraldehyde (1) are converted to 3,4,5-trimethoxybenzyl ethers 3 by a one-pot desilylation/alkylation. After deprotonation using potassium t-butoxide/t-butyllithium/N,N,N',N'-tetramethylethylenediamine in t-butyl methyl ether at -78 degrees C, substrates 3 undergo a [2,3]-sigmatropic Wittig rearrangement with complete 1,3-chirality transfer and good simple diastereoselectivity to give homoallyl alcohols 5 as the major products.