Nitrile analogs of meperidine as high affinity and selective sigma-1 receptor ligands

A series of N-substituted-4-cyano-4-phenylpiperidine analogs were synthesized and evaluated for binding affinity at opioid receptors and showed no affinity. The series similarity to previously reported σ ligands prompted analysis at σ receptors to determine the SAR for affinity at σ receptors. Within the N-substituent series the saturated analogs showed increased affinity at both σ receptors. Optimal chain length in the N-arylalkyl series for σ1 and σ2 receptors proved to be N-propylphenyl; extension to a four carbon chain dramatically decreased affinity at both receptors. Substituents in the 4-position affect only σ1 affinity; no change in affinity at σ2 was shown. The N-isobutyl, N-phenylpropyl, and N-benzyl analogs are worth pursuing due to their good affinity and selectivity at the σ1 receptor, whereas the N-benzyl analog exhibits the greatest selectivity for σ1.

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