Synthesis, Analytical Characterization, and Human CB₁ Receptor Binding Studies of the Chloroindole Analogues of the...

Synthetic cannabinoids (SCs) are one of the largest groups of new psychoactive substances (NPSs). However, the relationship between their chemical structure and the affinity to human CB₁ receptors (hCB₁), which mediates their psychotropic activity, is not well understood. Herein, the synthesis of the 2-, 4-, 5-, 6- and 7-chloroindole analogues of the synthetic cannabimimetic MDMB-CHMICA, along with their analytical characterization via ultraviolet-visible (UV/VIS), infrared (IR), nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry, is described. Furthermore, all five derivatives of MDMB-CHMICA were analyzed for their hCB₁ binding affinities. Chlorination at position 4 and 5 of the indole core reduced the binding affinity compared to MDMB-CHMICA, while the test compounds chlorinated in positions 2, 6, and 7 largely retained their binding affinities relative to the non-chlorinated parent compound.