Substituted diarylmethylamines by stereospecific intramolecular electrophilic arylation of lithiated ureas

On lithiation, N-benzyl ureas varying N'-aryl substituents undergo a migration of the aryl ring to the alpha carbon of the N-benzyl group. With chiral, enantiomerically pure N-alpha-methylbenzyl ureas, the rearrangement is stereospecific and creates a new, fully substituted stereogenic center alpha to N. Removal of the urea function by N-nitrosation and hydrolysis allows the synthesis of chiral tertiary carbinamines in high enantiomeric purity.