SYNTHESIS AND PHARMACOLOGICAL EVALUATION OF 18,19-DEHYDROBUPRENORPHINE

18,19-Dehydrobuprenorphine (2) was prepared in five steps starting from thevinone (3) which is readily available from thebaine by Diels-Alder reaction. Grignard reaction with tert-BuMgBr afforded tert-butylthevinol (4) which was N-demethylated via N-cyano-tert-butylthevinol (5) using BrCN. Alkali treatment gave N-nor-tert-butylthevinol (6) which was alkylated with cyclopropylmethyl bromide to give N-cyclopropylmethyl-tert-butylthevinol (7), followed by ether cleavage with thiolate to yield 2. 18,19-Dehydrobuprenorphine displayed in opioid receptor binding studies very high affinity for mu receptors, while the affinity for kappa and delta receptors was lower. In the tail-flick test in mice, compound (2) was 25 times more potent than morphine and ca. 2.5 times as potent as buprenorphine

Synthesis and Biological Evaluation of 14-Alkoxymorphinans. 22. Influence of the 14-Alkoxy Group and the Substitution in Position 5 in 14-Alkoxymorphinian-6-ones on in Vitro and in Vivo Activities

Novel 14-alkoxy-substituted (e.g. allyloxy, benzyloxy, naphthylmethoxy) morphinan-6-one derivatives were synthesized and biologically evaluated. Compounds 6-9 and 11 displayed affinities in the subnanomolar range mu opioid receptors which were comparable to 14-O-methyloxymorphone (1) and 14-methoxymetopon (3), and higher than oxymorphone (2). Opioid binding affinity was sensitive to the character and length of the substituent in position 14. In smooth muscle preparations they behaved as potent agonists. Antinociceptive potencies of compounds 6-11 in the hot-plate test after sc administration in mice were considerably greater than the potency of morphine. In the colonic propulsion test, the most potent analgesic compound 7 showed negligible constipating activity at the analgesic dose. These findings provide further evidence that the nature of the substituent at position 14 has a major impact on the abilities of morphinans to interact with opioid receptors. Introduction of a 5-methyl group has no significant effect on in vitro biological activities, but resulted in decreased antinociceptive potency