Novel Synthesis of the Natural Protoberberine Alkaloids: Oxypalmatine and Oxypseudopalmatine

摘要

Oxypalmatine and oxypseudopalmatine were synthesized in three steps from the benzonitrile 11 and toluamides 12a, b. The lithiated cycloaddition reaction yielded 3-arylisoquinolinone intermediates. A subsequent internal S_N2 reaction produced the corresponding 8-oxoprotoberberines, oxypalmatine and oxypseudopalmatine.