Synthesis of (+)-cis-N-(4-isothiocyanatobenzyl)-N-normetazocine, an isothiocyanate derivative of N-benzylnormetazocine as acylant agent for the sigma(1) receptor

(+)-cis-N-(4-Isothiocyanatobenzyl)-N-normetazocine (BNIT) (+)-(4) was designed and synthesized as a derivative of the potent and selective sigma(1) receptor ligand (+)-cis-N-benzyl-N-normetazocine for irreversibly blocking sigma(1) binding sites. Pretreatment of guinea pig brain membranes with BNIT (0.1, 1, and 5 microM) caused a concentration-dependent loss of binding of the selective sigma(1) ligand [(3)H]-(+)-pentazocine. Binding experiments with [(3)H]-1,3-di(2-tolyl)guanidine ([(3)H]-DTG), a ligand of sigma(1) and sigma(2) receptors, showed that pretreatment with BNIT blocked only the sigma(1) component of [(3)H]-DTG binding.