Various enantioselective allylations and crotylations of tert-butyldimethylsilyl-protected vanillin were undertaken to assess the best methodology to provide the corresponding homoallylic alcohols in high yields with high enantiopurity. In general, most of the tested allylations proceeded with high enantioselectivities (>92%ee) and in the case of crotylation also with excellent diastereoselectivity (96%ee, >98%de).
The product obtained from the crotylation reaction was used in the enantioselective synthesis of the unnatural diastereoisomer of a recently isolated lignan derivative.