Alkaloids of Caryomene olivascens (Menispermaceae). Bisbenzylisoquinoline with new structure.

Nine isoquinoline alkaloids belonging to the protoberberine, proaporphine and bisbenzyl-isoquinoline series were isolated from Caryomene olivascens (Menispermaceae). Four compounds are new : (-)-2-norlimacine (4), (-)-caryolivine (6), (+)-1, 2-dehydro-2-norlimacusine (9) and N-formylstepharine (3). The last one is the first N-formyl derivative to be reported in the proaporphine group. Its biogenetic origin is discussed. Structures were established on the basis of 360 MHz (FT) nuclear magnetic resonance measurements and also by chemical correlation in the case of 3.