Total synthesis of the opioid agonistic indole alkaloid mitragynine and the first total syntheses of 9-methoxygeissoschizol and 9-Methoxy-Nb-methylgeissoschizol

An enantiospecific method for the synthesis of 4-methoxytryptophan has been developed via a regiospecific Larock heteroannulation and employed for the first total syntheses of 9-methoxygeissoschizol and 9-methoxy-N-b-methylgeissoschizol, as well as the total synthesis of the opioid agonistic alkaloid mitragynine. The asymmetric Pictet-Spengler reaction and a Ni(COD)(2)-mediated cyclization served as key steps.