Photochemically Assisted Introduction of a Benzyl Unit into Isoquinolines Using Benzyltrifluoroborates

Isoquinoline was photochemically benzylated at its 1 position with benzyltrifluoroborate reagents in the presence of methyl chloroformate. When a benzyl group substituted by an electron-donating group was employed, the benzylation thermally proceeded. The present reaction allowed straightforward synthesis of the skeleton for the benzylisoquinoline alkaloid.