Elaboration of 1-benzoyltetrahydroisoquinoline derivatives employing a Pictet–Spengler cyclization with α-chloro-α-phenylthioketones. Synthesis of O-methylvelucryptine

The reaction of N-tosyl-β-phenethylamines with α-chloro-α-phenylthioketones, leading to 1-benzoyl- and 1-pivaloyl-tetrahydroisoquinolines under modified Pictet–Spengler conditions, is described. The synthesis of O-methylvelucryptine employing this transformation as a key step is reported.