Abstract
The synthesis of dl-cepharamine (4) which is a member of hasubanan alkaloids, was accomplished after the model experiments started from 2-tetralone (5) were examined. The keto-lactam (30) was synthesized from 7, 8-dimethoxy-2-tetralone (7) via the keto-ester (27) or the keto-nitrile (53). Ketalization of the compound (30), followed by treatment under the Wolff-Kishner reaction condition caused by demethylation of a methoxyl group at C4 to result in the phenolic compound (63). Acetylation of the compound (63), followed by deketalization gave the keto-acetate (65). The diketone (67) was synthesized by bromination of the compound (65) with two equivalents of bromine, followed by heating with anhydrous sodium acetate in acetic acid. The target molecule, dl-cepharamine (4), was synthesized from the diketone (67) by successive treatments with BF3·ether-MeOH (monoenolmethylation), LiAlH4 reduction and oxidation with DMSO-phosphoric acid-DCC.
