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Paper | Regular issue | Vol 38, No. 4, 1994, pp.877-881
Published online, 1st January, 1970
DOI: 10.3987/COM-93-S(B)11
A New and Efficient Synthesis of the μ-Selective Opioid Antagonist Cyprodime

Roland Krassnig and Helmut Schmidhammer*

*Institute of Pharmaceutical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria

Abstract

The μ-selective opioid antagonist cyprodime has been prepared in a six-step sequence starting from naltrexone. The 3-hydroxy group of naltrexone was removed via tetrazolyl ether (3) which was hydrogenated catalytically to give 17-cyclopropylmethyl-4,5α-epoxy-14-hydroxymorphinan-6-one (4). Methylation gave 17-cyclopropylmethyl-6,7-didehydro-4,5α-epoxy-6,14-dimethoxymorphinan (5) and hydrolysis of it 17-cyclopropylmethyl-4,5α-epoxy-14-methoxymorphinan-6-one (6). Reductive opening of the 4,5-epoxy bridge and methylation of the resulting phenol (7) yielded cyprodime (1).