Previous work in our laboratories investigating compounds with structural similarity to ifenprodil (5) and 6 (CP101, 606) resulted in compound 7 as a potent and selective antagonist of the NR1/2B subtype of the NMDA receptors. Replacement of the phenol group of 7 with a benzimidazalone group tethered by a three-carbon chain to 4-benzylpiperidine resulted in a slightly less active, but selective, compound. Lengthening the carbon tether ...