Maat L, Woudenberg RH, Meuzelaar GJ, Linders JT. Chemistry of opium alkaloids. Part 44: synthesis and opioid receptor binding profile of substituted ethenoisomorphinans and ethenomorphinans.
Bioorg Med Chem 1999;
7:529-41. [PMID:
10220038 DOI:
10.1016/s0968-0896(98)00267-3]
[Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
7- and 8-substituted 6alpha,14alpha-ethenoisomorphinans were synthesized by reaction of properly substituted morphinan-6,8-dienes (analogues of thebaine) with methyl vinyl ketone or ethyl acrylate. Reaction with the appropriate Grignard reagent gave the 7- and 8-dialkylmethanols, respectively. Cleavage of the 3-methyl ether with KOH/glycol or boron tribromide afforded the 3-hydroxyl derivatives. In general, the compounds with the ethoxycarbonyl or dimethylmethanol substituent at the 8alpha-position showed lower affinity for the mu, kappa, and delta opioid receptor subtypes than the corresponding 7alpha- and 7beta-substituted compounds. Introduction of a chloro substituent in position 18 increased the potency significantly. The 7-substituent could be connected to the 18-position without loss of affinity. 5Beta-alkyl substitution of 6alpha,14alpha-ethenoisomorphinans led to a decrease in affinity for the three opioid receptor subtypes. In the 5beta-methyl series the affinity for the mu and delta receptors increased from 7alpha-dimethylmethanol to 7alpha-methylhexylmethanol. In the 5beta-alkyl series, the affinity for the mu-receptor could be increased by connecting the 5- and 7-substituents, yielding a compound with high mu-selectivity. The new 6beta,14beta-ethenomorphinans did not show affinity for any of the opioid receptors, in accordance with the inactivity earlier found in in vivo experiments.
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