Metalated nitriles: electrophile-dependent alkylations.

[reaction: see text] Sequential carbonyl addition-conjugate addition to oxonitriles generates a C-magnesiated nitrile exhibiting electrophile-dependent alkylation stereoselectivities. Alkylations with alkyl halides, sulfonates, and ketones proceed with retention of stereochemistry, whereas aldehyde and acyl cyanide acylations proceed with inversion of stereochemistry. BuLi-initiated conversion of the C-magnesiated nitrile to the corresponding N-lithiated nitrile reverses the alkylation stereoselectivity, providing a facile route to diastereomeric nitriles that vary at a single, quaternary stereocenter.