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A series of pethidine analogs were synthesized and their affinities for the [3H]N-methyl-scopolamine (NMS) binding site on muscarinic acetylcholine receptors (mAChRs) were determined using M1, M3 or M5 human mAChRs expressed by Chinese hamster ovary (CHO) cell membranes. Compound 6b showed the highest binding affinities at M1, M3 and M5 mAChRs (Ki = 0.67, 0.37, and 0.38 μM, respectively).

The present invention relates to new phenylpiperidine modulators of μ-opioid receptors, pharmaceutical compositions thereof, and methods of use thereof.

Numerous studies have shown that many clinically employed opioid analgesics are substrates for P-glycoprotein (P-gp), suggesting that up-regulation of P-gp may contribute to the development of central tolerance to opioids. The studies herein focus on the development of SAR for P-gp substrate activity in the meperidine series of opioids. Addition of a 3-OH to meperidine and the ketone analog of meperidine yielding bemidone and ketobemidone, respectively, significantly increased P-gp substrate affinity. The results of this study have implications in the development of novel analgesics to be utilized as tools to study the contribution of P-gp on the development of central tolerance to opioids.

P-Glycoprotein (P-gp) is an efflux transporter which is up-regulated at the blood-brain barrier in both morphine- and oxycodone-tolerant rats. Numerous studies have shown that many clinically employed opioid analgesics are substrates for P-gp, suggesting that up-regulation of P-gp may contribute to the development of central tolerance to opioids. The studies herein focus on the development of SAR for P-gp substrate activity in the meperidine series of compounds, and show that a meperidine analog of greater potency, N-phenylbutyl-N-normeperidine, has low activity as a P-gp substrate and has the potential to be utilized as a tool to study the contribution of P-gp to the development of central tolerance to opioids.

Improvements are shown in the successive preparations of N,N-bis(2-hydroxyethyl)benzylamine starting with benzyl chloride, its conversion to the corresponding N,N-bis(2-chloroethyl)benzylamine in substantially quantitative yield in toluene solution and using the latter by reaction with phenylacetonitrile in the presence of aqueous sodium hydroxide solution and a tetra-n-butylammonium salt, preferably the hydrogen sulfate, to produce improved over-all yields of up to over 75% (based on benzyl chloride) of 1-benzyl-4-cyano-4-phenylpiperidine hydrochloride, an intermediate for preparing meperidine.

The electrophilic reactivity of arenes coordinated to the chromium tricarbonyl unit has been developed into several distinct methods for coupling carbon nucleophiles with aromatic rings.Addition of the nucleophile produces stable η-cyclohexadienyl chromium complexes which can be oxidized to induce loss of the endo hydrogen and the metal, overall nucleophilic substitution for hydrogen.Alternatively, the intermediate can be protonated and the resulting cyclohexa-1,3-diene can be detached from the chromium, effecting nucleophilic addition with reduction of one double bond.If a halogen (F, Cl) is present as a ring substituent, and if the nucleophile can migrate about the arene ligand, then loss of halide can occur parallel with classical nucleophilic aromatic substitution for halogen in electron-deficient haloarenes.With substituted arenes, the regioselectivity of addition becomes important and is often very high.Particularly useful are strong resonance donor substituents (RO-, R2N-, F-) where selectivity for meta attack is high.Indole provides an excellent example of selective activation, as the six-membered ring complexes selectively and is then susceptible to nucleophilic substitution, predominantly at the 4 and 7 positions.Substitution for halogen is a somewhat limited process and depends upon the nature of the nucleophile.Very reactive nucleophiles add to unsubstituted positions and are often slow to isomerize to the ipso position from which loss of halide can occur.

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