One-pot synthesis of N-methylindoles from N-methylanilines and of benzofurans from phenols using transition-metal carbene X–H insertion reactions

Transition-metal carbene X–H insertion reactions (X=N or O) have been employed in the simple conversion of anilines and phenols into indoles and benzofurans, respectively. Thus copper(II) catalyzed N–H insertion reactions of α-diazo-β-ketoesters with N-methylanilines followed by treatment with acidic ion-exchange resin gives indoles. In a similar manner, dirhodium(II) catalyzed O–H insertion reactions of α-diazo-β-ketoesters with phenols followed by treatment with PPA gives benzofurans.