Amines bearing tertiary substituents by tandem enantioselective carbolithiation-rearrangement of vinylureas

In the presence of (-)-sparteine or a (+)-sparteine surrogate, organolithiums add to N-alkenyl-N'-arylureas to give benzylic organolithiums in an enantioselective manner. Under the influence of DMPU, these organolithiums undergo rearrangement with migration of the N'-aryl ring from N to C, leading to the urea derivatives of enantiomerically enriched amines bearing tertiary substituents. Basic hydrolysis returns the functionalized amine, providing a new synthetic route to compounds with quaternary stereogenic centers bearing nitrogen.