Photochemical Synthesis of Benzylisoquinoline Alkaloids Using Tetra-coordinate Benzylboron Reagents: Application to Berberine Type Alkaloids

Abstract Photochemical and selective synthesis of 1-benzyl-1,2-dihydroisoquinolines was achieved from isoquinolines, methyl chloroformate and electron-rich benzyltrifluoro-borates in the presence of pyridine that inhibited subsequent formation of possible cyclized pavine type products. The benzyl adducts were successfully transformed into berberine type skeletons by the cyclization at the carbamate moiety.