1983 Volume 31 Issue 6 Pages 2172-2175
Acidic treatment of the 8, 14-cycloberbine (12), derived from the protoberberine (8), effected regioselective ring cleavage to afford the cis-benzindenoazepine (15) along with a small amount of the trans-derivative (16) after N-methylation. Hydrogenolysis of 15 provided fumarofine (1), which was methylated with diazomethane to give O-methyl-fumarofine (2).