The total synthesis of the crinine alkaloid hamayne via a Pd[0]-catalyzed intramolecular alder-ene reaction

The racemic form of the title alkaloid, 1, has been prepared in 13 steps from the ring-fused gem-dibromocyclopropane 7. Key transformations include the thermally induced electrocyclic ring-opening of compound 7, the Pd0]-catalyzed intramolecular Alder-ene (IMAE) reaction of the derived sulfonamide (±)-12, and the conversion of the ensuing C-3a-arylhexahydroindole (±)-16 into (±)-hamayne via a Pictet-Spengler reaction.