Potential long acting opiate antagonists: preparation, pharmacological activity, and opiate-receptor binding of N-substituted 2'-hydroxy-5-methyl-9 alpha-propyl-6,7-benzomorphans.

A homologous series of N-substituted 2'-hydroxy-5-methyl-9 alpha-propyl-6,7-benzomorphans (hydrogen to octyl inclusive, allyl, and cyclopropylmethyl) was prepared. In contradistinction to the normetazocine, normorphine, and (-)-3-hydroxymorphinan series, the N-pentyl and N-hexyl derivatives do not have the analgesic potency of the parent N-methyl compound; instead, they are narcotic antagonists with a long duration of action. All of the N-substituted 9 alpha-propylbenzomorphans, except for methyl, heptyl, and octyl, have antagonist activity. The receptor binding constants of the N-alkyl compounds are uniformly two- to threefold lower than those of the N-substituted normetazocines.