Carbolithiation of N-alkenyl ureas and N-alkenyl carbamates

N-Alkenyl ureas and N-alkenyl carbamates, like other N-acyl enamines, are typically nucleophilic at their β-carbon. However, by incorporating an α-aryl substituent, we show that they will also undergo attack at the β-carbon by organolithium nucleophiles, leading to the products of carbolithiation. The carbolithiation of E and Z N-alkenyl ureas is diastereospecific, and N-tert-butoxy-carbonyl N-alkenyl carbamates give carbolithiation products that may be deprotected in situ to provide a new connective route to hindered amines.