SYNTHESIS OF (+)-(1'R,2'S) AND (1'S,2'R)-6,11-DIMETHYL-1,2,3,4,5,6-HEXAHYDRO-3-[[2'-(ALKOXYCARBONYL)-2'-PHENYLCYCLOPROPYL]METHYL]-2,6-METHANO-3-BENZAZOCIN-8-OL. COMPARISON OF THE AFFINITIES FOR SIGMA 1 AND OPIOID RECEPTORS WITHIN THE DIASTEREOISOMERIC MPCB AND CCB

The synthesis and the in vitro receptor affinity for sigma 1 and opiod receptors of the two diastereoisomers of (+)-cis-MPCB namely, (+)-cis-(1'S,2'R)-6,11-Dimethyl-1,2,3,4,5,6 -hexahydro-3-[[2'-(methoxycarbonyl)-2'-phenylcyclopropyl]methyl]-2 ,6 -methano-3-benzazocin-8-ol, (1'S,2'R)6a and (+)-cis-(1'R,2'S)-6,11-Dimethyl-1,2,3,4,5,6-hexahydro-3- [[2-(methoxycarbonyl)-2'-phenylcyclopropyl]methyl]-2,6-methano-3-+ ++benzazocin-8 -ol, (1'R,2'S)6a are reported. Affinities of (1'S,2'R)6a and (1'R,2'S)6a were compared with those of the (-)-cis-diastereoisomers of MPCB(1), and of its p-Cl phenyl derivative CCB(2). The (+)-cis-N-normetazocine derivatives showed higher affinity for the sigma 1 sites, labeled with [3H]-(+)-pentazocine than the corresponding (-)-cis- analogs. In particular, compound (1'S,2'R)6a showed a Ki =66.7 nM for sigma 1 receptor, associated with a good selectivity for sigma 1 with respect to kappa, mu, delta opioid receptors subtypes (Ki = > 1,000 nM). Analysis of the data seem to support the hypothesis that the (+)-cis-N-normetazocine nucleus posses a specific enantioselectivity for sigma 1 sites, when supporting bulkier N-substituents functionalized with a carboxy ester group.