Reaction of bisbenzylisoquinoline alkaloids with ceric ammonium nitrate: A new degradative procedure

Abstract

Ceric ammonium nitrate cleaved laudanosine (1) quantitatively into veratraldehyde (2) and 6,7-dimethoxy-2-methyl-3,4-dihydroisoquinolinium ion (3), isolated as the reduced product, 6,7-di-methoxy-2-methyl-1,2,3,4-tetrahydroisoquinoline (4). The reagent also degraded tetrandrine (5), hernandezine (6) and O-methylmicranthine (7) in a similar way; the products after reduction were isolated as diamines [(8), (9) and (10) respectively] and a diol, 3-[4'- (hydroxymethyl)phenyloxy]-4-methoxybenzyl alcohol (11), in nearly quantitative yields. When applied to berbamine (12), thalibrunine (13) and tenuipine (14), this reaction gave good yields of the nitrogen-containing fragments only.