Tricyclic pyrazoles. Part 2: Synthesis and biological evaluation of novel 4,5-dihydro-1H-benzo[g]indazole-based ligands for cannabinoid receptors

A series of 4,5-dihydro-1H-benzo[g]indazole-3-carboxamides (2a–k) as analogues of the previously reported CB2 ligands 6-chloro- and 6-methyl-1-(2′,4′-dichlorophenyl)-N-piperidin-1-yl-1,4-dihydroindeno[1,2-c]pyrazole-3-carboxamides (1a,b) was synthesized and their affinity and selectivity towards CB1 and CB2 receptors were evaluated. Several of the new compounds (2a,b,c,d and i) exhibited CB1 affinity in the nanomolar range with moderate or negligible affinity towards CB2 receptors. Compounds 2a and c increased intestinal propulsion in mouse. Their pro-kinetic effects were reversed by the reference CB agonist CP-55,940. Consequently, in vivo CB1 antagonistic activity was highlighted for these compounds.

Synthesis, CB1 and CB2 receptor affinities of 4,5-dihydro-1H-benzo[g]indazole carboxamides (2) are described. For some compounds the prokinetic effect is also evaluated.Figure optionsDownload as PowerPoint slide