Preparation of organoaluminum reagents from propargylic bromides and aluminum activated by PbCl2 and their regio- and diastereoselective addition to carbonyl derivatives.

Various propargylic and allenic aluminum reagents have been easily prepared by a direct insertion of aluminum into propargylic bromides in the presence of PbCl(2) (1 mol%). These organoaluminum reagents react with carbonyl compounds to afford the corresponding allenic alcohols or homopropargylic alcohols in good to excellent yields with high regio- and diastereoselectivity.