A facile preparation and cyclopropanation of 1-alkenylsilanols

Alkenylsilanols are prepared by the reaction of hexamethyltrisiloxane (D-3) With alkenyllithiums or alternatively by the reaction of cyclic siloxanes substituted by an alkenyl group with organolithiums and transformed to the corresponding cyclopropylsilanols using diiodomethane and diethylzinc. Lithium alkenylsilanolates, primary products of the preparation, also undergo cyclopropanation. As in the case of allylic alcohols, the silanol functionality is found to enhance the rate of cyclopropanation compared with that of alkenyltrialkylsilane or alkoxydialkylsilane. The obtained cyclopropylsilanols are further converted into the corresponding cyclopropanols by the Tamao oxidation.