Aryl-coupling via axially prostereogenic lactones: first total synthesis of (+)-ancistrocladisine and (optionally) its atropisomer

Abstract The first total synthesis of the liana alkaloid ancistrocladisine ( 1a ) and of its novel atropisomer 1b is reported. The required mixed aryl coupling is brought about, regiospecifically, by prefixation of the two molecular moieties by an ester-type auxiliary bridge. A methodology is described for the recycling of the undesired, configurationally stable atropisomer 9b , via the “axially prostereogenic” lactone 8 - chiral economy with respect to rotational isomerism.