Visible Light Driven Metal-Free Photoredox Catalyzed α-benzylation and α-oxygenation of N-substituted Tetrahydroisoquinolines: Applications to Synthesis of Natural Products.

Herein, visible light mediated organophoto redox catalysed simple and convenient method for the α-benzylation and α-oxygenation of tertiary amines is demonstrated. Synthesis of novel thiophenol based donor acceptor organophotoredox catalysts 4 a-4 d were investigated along with commercial catalyst 4-CzIPN (4 e). A diverse biologically active α-benzylated tetrahydroisoquinolines and natural products such as (±)-Norlaudanosine, (±)-laudanosine and (±)-xylopinine have been synthesized under the optimized conditions in yields ranging from from 62-91%.