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Paper | Special issue | Vol 37, No. 3, 1994, pp.1657-1671
Published online, 1st January, 1970
DOI: 10.3987/COM-93-S135
Synthetic Studies on Colchicine: Reaction of Homomorphinandienones

Hiromichi Ogasawara, Shin-ichi Tasaki, Fumiaki Mutoh, Hiroshi Hara, Hiroharu Nishikawa, Mitsuaki Tanaka, and Osamu Hoshimo*

*Faculty of Pharmaceutical Sciences, Science University of Tokyo, 12, Ichigaya Funagawara-machi, Shinjuku-ku, Tokyo 162-0826, Japan

Abstract

For the purpose of synthetic approaches toward colchicine (2) from O-methylandrocymbine (1a), reaction of homomorphinandienones (1a,b) was carried out. Oxidation of 1a,b with 35% aqueous hydrogen peroxide gave a separable diastereomeric mixture of N-oxides (5,6). Polonovski reaction of the N-oxides (5) with acetic anhydride in CH2Cl2 afforded N-demethyl-N-acetamide (7a), whereas that of 5 and 6 with acetic anhydride in the presence of triethylamine gave enamines (8a,b) together with N-demethyl-N-acetamides (7a,b). Furthermore, reaction of enamines (8a,b) with N-bromosuccinimide in dimethoxyethane-H2O or methanol produced α-bromo amides (9a,b).