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Communication | Special issue | Vol 8, No. 1, 1977, pp.119-124
Published online, 1st January, 1970
DOI: 10.3987/S(S)-1977-01-0119
A Stereoselective Formal Total Synthesis of Emetine

Tetsuji Kametani,* Yukio Suzuki, Hirofumi Terasawa, Masataka Ihara, and Keiichiri Fukumoto

*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan


Condensation of 3,4-dihydro-6,7-dimethoxy-1-methylisoquinoline (2) with dimethyl 3-methoxyallylidene-malonate (3) gave 2,3,6,7-tetrahydro-9,10-dimethoxy-3-methoxycarbonyl-2-(α,β-dimethoxyethyl)benzo[a]quinolizin-4-one (4) which was converted to (±)-dihydroprotoemetine (10a). Decarboxylation of the 3-carboxybenzo[a]quinolizin-4-one (6) gave mainly the cis-isomer (7b), whose stereochemistry could be transformed to the thermodynamically stable form (8a) by epimerization at the stage of the hexahydrobenzo[a]quinolizin-4-one (8b).