Tandem β-Alkylation-α-Arylation of Amines by Carbolithiation and Rearrangement of N-Carbamoyl Enamines (Vinyl Ureas)

Organolithiums add in an umpolung fashion to the beta-carbon of N-carbamoyl enamines (N-vinyl ureas). The reaction proceeds with syn diastereospecificity and provides urea-stabilized, configurationally defined organolithiums. Facilitated by coordinating solvents (THF or DMPU), these undergo intramolecular attack on an N'-aryl group, resulting in retentive arylation of the organolithium and hence overall addition of an alkyl or aryl group to both carbon atoms of the urea-substituted alkene. Facile deprotection in hot butanol permits the rapid, multicomponent construction of heavily substituted amines.