Synthesis and structure-activity relationships of N-benzyl phenethylamines as 5-HT2A/2C agonists.

Adding a benzyl group to the nitrogen atom of phenethylamine psychedelics like 2C-B greatly increases their binding and activity at serotonin 5-HT2A receptors. A library of 48 compounds with varied phenethylamine and N-benzyl structures was tested. Most had high 5-HT2A affinity; compound 8b showed the highest affinity at 0.29 nM, while 1b was the most functionally potent at 0.074 nM. Selectivity over the related 5-HT2C receptor ranged from 1- to 40-fold in binding, though 6b achieved 100-fold selectivity. Functional selectivity was higher, with 1b exceeding 400-fold selectivity for 5-HT2A.

Study at a glance

Abstract

N-Benzyl substitution of 5-HT2A receptor agonists of the phenethylamine structural class of psychedelics (such as 4-bromo-2,5-dimethoxyphenethylamine, often referred to as 2C-B) confer a significant increase in binding affinity as well as functional activity of the receptor. We have prepared a series of 48 compounds with structural variations in both the phenethylamine and N-benzyl part of the molecule to determine the effects on receptor binding affinity and functional activity at 5-HT2A and 5-HT2C receptors. The compounds generally had high affinity for the 5-HT2A receptor with 8b having the highest affinity at 0.29 nM but with several other compounds also exhibiting subnanomolar binding affinities. The functional activity of the compounds was distributed over a wider range with 1b being the most potent at 0.074 nM. Most of the compounds exhibited low to moderate selectivity (1- to 40-fold) for the 5-HT2A receptor in the binding assays, although one compound 6b showed an impressive 100-fold selectivity for the 5-HT2A receptor. In the functional assay, selectivity was generally higher with 1b being more than 400-fold selective for the 5-HT2A receptor.