Methyl 1,2,4,5,6,10b-hexahydro-8,9-methylenedioxy-2- oxobenzo[d]cyclopenta[b]azepine-4-carboxylate

The title compound contains the tetracyclic A-B-C-E ring system of cephalotaxus alkaloids. Unexpectedly, the five-membered-ring plane is twisted 67.2 degrees from the aromatic ring plane and, like cephalotaxine, the seven-membered ring is oriented in a boat form with the nitrogen at the prow.