Synthesis and evaluation of substituted 2-phenylcyclobutylamines as analogs of hallucinogenic phenethylamines: lack of LSD-like biological activity

Three new compounds—cis- and trans-2-(2,4,5-trimethoxyphenyl)cyclobutylamine and trans-2-(2,5-dimethoxy-4-methylphenyl)cyclobutylamine—were synthesized as rigid versions of hallucinogenic phenylisopropylamines. In rats trained to distinguish LSD from saline, the cis compound did not produce LSD-like effects at doses up to 20 mg/kg. Both trans compounds partially mimicked LSD at 5 mg/kg or higher. In contrast, a related cyclopropylamine compound fully substituted for LSD. The trans cyclobutylamines were about 50 to 75 times less potent than the cyclopropylamine analogue. The lack of full generalization suggests these cyclobutylamines either produce different effects from LSD or lack discriminative effects entirely.

Study at a glance

Abstract

cis- and trans-2-(2,4,5-trimethoxyphenyl)cyclobutylamine and trans-2-(2,5-dimethoxy-4-methylphenyl)cyclobutylamine were synthesized as conformationally restricted analogues of hallucinogenic phenylisopropylamines. In rats trained to discriminate saline from LSD (0.08 mg/kg, ip) in a two-lever drug discrimination paradigm, no generalization of the LSD stimulus to the cis trimethoxy compound occurred at doses up to 20 mg/kg. For both of the trans compounds, partial generalization of the LSD cue occurred at doses of 5 mg/kg or greater. In contrast, complete generalization occurred with trans-2-(2,5-dimethoxy-4-methylphenyl)cyclopropylamine. The ED50 for this compound and the doses of the trans cyclobutyl homologues at which significant drug-appropriate responding occurred indicate that the latter are on the order of 50-75 times less potent than the cyclopropylamine analogue. The lack of generalization to the cyclobutylamines indicates either that their discriminative stimulus properties differ from LSD or that they lack discriminative effects.