Radical fixation of functionalized carbon resources: α-sp ³C - H carbamoylation of tertiary amines with aryl isocyanates

A new carbamoylation of tertiary amines is reported. This rare C - H transformation features the direct generation of α-aminoalkyl radicals from tertiary amines, followed by the addition of the resultant nucleophilic radicals to isocyanates, enabling unique access to N,N-dialkylated amino acid derivatives. The authors put forward a mechanistic proposal that is based on the isolation of borinamides produced by capturing nitrogen radical intermediates with Et₃B. The present transformation provides a novel one-step process for producing mepivacaine, a clinically important local anesthetic, from readily available materials.