N-(Biphenyl-3-ylmethyl)ethanamines as G protein-biased agonists of 5-HT₇R

There has been much attention to biased ligands of G protein-coupled receptors (GPCRs) for potential pharmacological benefits. Recently, we reported N-((6-chloro-2'-methoxy-[1,1'-biphenyl]-3-yl)methyl)ethanamine 1 as G protein-biased agonist of 5-HT₇R, which could be used as a chemical probe for the study on treatment discovery of autism spectrum disorder. Herein, we describe the synthesis of derivatives of the compound 1 and their biological evaluations in both G protein and β-arrestin signaling pathway. Total 16 compounds were synthesized and evaluated, and the compounds 3c, 3f, 3i, and 3p could be called as G protein-biased agonists like the compound 1. Among the four compounds, the compound 3c was the best in efficacy with an E_max value of 73% and the compound 3f was the most potent agonist with an EC₅₀ value of 0.094 μM.