The vanilloid receptor-1 (TRPV1 or VR1) is a member of the transient receptor potential (TRP) family of ion channels and plays a role in regulating the function of sensory nerves. A growing body of evidence demonstrates the therapeutic potential of TRPV1 modulators, particularly in the management of pain. As a result of our screening efforts, we identified (E)-3-(4-tert-butylphenyl)-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)acrylamide (1), an antagonist that blocks the capsaicin-induced and pH-induced uptake of (45)Ca(2+) in TRPV1-expressing Chinese hamster ovary cells with IC(50) values of 17 +/- 5 and 150 +/- 80 nM, respectively. In this report, we describe the synthesis and structure-activity relationship of a series of N-aryl cinnamides, the most potent of which (49a and 49b) exhibit good oral bioavailability in rats (F(oral) = 39% and 17%, respectively).

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Neuropeptide Y (NPY) has been shown to play an important role in the regulation of food intake and energy balance. Pharmacological data suggests that the Y5 receptor subtype contributes to the effects of NPY on appetite, and therefore a Y5 antagonist might be a useful therapeutic agent for the treatment of obesity. In attempts to identify potential Y5 antagonists, a series of pyrrolo[3, 2-d]pyrimidine derivatives was prepared and evaluated for their ability to bind to Y5 receptors in vitro. We report here the synthesis and initial structure-activity relationship investigations for this class of compounds. The target compounds were prepared by a variety of synthetic routes designed to modify both the substitution and the heterocyclic core of the pyrrolo[3,2-d]pyrimidine lead 1. In addition to identifying several potent Y5 antagonists for evaluation as potential antiobesity agents, a pharmacophore model for the human Y5 receptor is presented.

The synthesis of 7-cyano-1,2,9,9a-tetrahydrocyclopropa[c]benz[e]indol-4-one (CCBI), a substituted CBI derivative bearing a C7 cyano group, is described in efforts that establish the magnitude of potential electronic effects on the functional reactivity of the agents. The CCBI alkylation subunit was prepared by a modified Stobbe condensation/Friedel−Crafts acylation for generation of the appropriately functionalized naphthalene precursors followed by 5-exo-trig aryl radical−alkene cyclization for synthesis of the 1,2-dihydro-3H-benz[e]indole skeleton and final Ar-3‘ alkylation for introduction of the activated cyclopropane. The most concise approach provided the CCBI subunit and its immediate precursor in 14−15 steps in superb overall conversions (15−20%). Resolution of an immediate CCBI precursor and its incorporation into both enantiomers of 34−39, analogs of CC-1065 and the duocarmycins, are detailed. A study of the solvolysis reactivity and regioselectivity of N-BOC-CCBI (25) revealed that introduction of the C7 nitrile slowed the rate of solvolysis but only to a surprisingly small extent. Classical Hammett quantitation of the effect provided a remarkably small ρ (−0.3), indicating an exceptionally small C7 substituent electronic effect on functional reactivity. Additional kinetic studies of acid-catalyzed nucleophilic addition proved inconsistent with C4 carbonyl protonation as the slow and rate-determining step but consistent with a mechanism in which protonation is rapid and reversible followed by slow and rate-determining nucleophilic addition to the cyclopropane requiring both the presence and assistance of a nucleophile (SN2 mechanism). No doubt this contributes to the DNA alkylation selectivity of this class of agents and suggests that the positioning of an accessible nucleophile (adenine N3) and not C4 carbonyl protonation is the rate-determining step controlling the sequence selectivity of the DNA alkylation reaction. This small electronic effect on the solvolysis rate had no impact on the solvolysis regioselectivity, and stereoelectronically-controlled nucleophilic addition to the least substituted carbon of the activated cyclopropane was observed exclusively. Consistent with past studies, a direct relationship between solvolysis stability and cytotoxic potency was observed with the CCBI-derived agents providing the most potent analogs in the CBI series, and these observations were related to the predictable Hammett substituent effects. For the natural enantiomers, this unusually small electronic effect on functional reactivity had no perceptible effect on their DNA alkylation selectivity. Similar effects of the C7 cyano substituent on the unnatural enantiomers were observed, and they proved to be 4−10× more effective than the corresponding CBI-based unnatural enantiomers and 4−70× less potent than the CCBI natural enantiomers.