Imidoylstannanes, improved preparation and uses as acylanion equivalents

An improved preparation of imidoylstannanes, by reaction of triorganostannyllithiums with imidoyl chlorides, is reported. This reaction is effective when phenyl or methyl groups are substituents on the tin atom, and when N-aryl C-alkyl or C-aryl imidoyl chlorides are used. After reaction with acyl chlorides, imidoylstannanes led to high yields of α-keto imines, which can be further hydrolysed into α-diketones. Transmetallation with organolithiums selectively gave the corresponding lithium reagents which showed a normal behaviour with alkyl halides, silicon halides, epoxides or chloroformates, leading to functional imines, hydrolysable to the corresponding ketones. This route forms a new entry to Walborski reagents.