Synthesis and pharmacological evaluation of triflate-substituted analogues of clozapine: Identification of a novel atypical neuroleptic

The trifluoromethanesulonyloxy (TfO) analogues 3 and 4 of 8-chloro-11-(4-methyl-1-piperazinyl)-5H-dibenzo[b,e][1,4]diazepine (clozapine, 1) and its 2-chloro isomer (iso-clozapine, 2), respectively, were synthesized via their OMe and OH analogues with the conventional synthetic method of the tricyclic dibenzodiazepines and evaluated pharmacologically along with their parent drugs. The binding profile of the 2-OTf analogue (4) is comparable to the binding profile of 1, although the affinity for the dopamine (DA) D-2 receptors is higher (IC50 values are 31 nM and 330 nM for compounds 4 and 1, respectively). Interestingly, no notable affinity for muscarinic receptors could be detected in compound 4. On the contrary, the 3-OTf analogue 3 only displayed affinity for muscarinic M-1 receptors (IC50 value 35 nM) and no affinity (IC50 value > 500 nM) for the other receptors tested. The 10 mu mol/kg sc dose, but nod the 10 mu mol/kg po dose, of compound 4 stimulated the output of DA, Increases of 80% and 35% in DOPAC output from the dorsal striatum were seen after sc and po administrations of 10 mu mol/kg of compound 4, respectively. Doses up to 100 mu mol/kg of compound 3 had no effect on either parameter. Doses up to 100 mu mol/kg of compound 4 were not cataleptogenic, but significantly decreased apomorphine-induced locomotor activity. In conclusion, compound 4 (GMC1-169) is a new clozapine-like neuroleptic candidate, which is lacking anticholinergic properties and displays a higher potency, as compared to clozapine (1) itself.