Conformational analysis, part 43. A theoretical and LIS/NMR investigation of the conformations of substituted benzamides.

A refined Lanthanide-Induced-Shift Analysis (LISA) is used with molecular mechanics and ab initio calculations to investigate the conformations of benzamide (1), N-methylbenzamide (2), N,N-dimethylbenzamide (3) and the conformational equilibria of 2-fluoro (4), 2-chloro (5) and N-methyl-2-methoxy benzamide (6). The amino group in 1 is planar in the crystal but is calculated to be pyramidal with the CO/phenyl torsional angle (ω) of 20-25°. The LISA analysis gave acceptable agreement factors (Rcryst ≤ 1%) for the ab initio geometries when ω was decreased to 0°, the other geometries were not as good. In 2, the N-methyl is coplanar with the carbonyl group in all the geometries. Good agreement was obtained for the RHF geometries, with ω 25°, the other geometries were only acceptable with increased values of ω. In 3, good agreement for the RHF and PCModel geometries was found when ω was changed from the calculated values of 40° (RHF) and 90° (PCModel) to ca. 60°, the X-ray and B3LYP geometries were not as good. The two substituted compounds 4, 5 and 6 are interconverting between the cis (O,X) and trans (O,X) conformers. The more stable trans conformer is planar in 4 and 6 but the cis form non-planar. Both the cis and trans conformers of 5 are non-planar. There is an additional degree of freedom in 6 due to the 2-methoxy group, which can be either planar or orthogonal to the phenyl ring in both conformers. The conformer ratios were obtained from the LISA analysis to give Ecis-Etrans in 4 > 2.3 kcal/mol (CDCl3 ) and 1.7 kcal/mol (CD3 CN), in 5 0.0 kcal/mol (CD3 CN) and in 6 > 2.5 kcal/mol (CDCl3 ) and 2.0 kcal/mol (CD3 CN). These values were used with the observed versus calculated (1) H shifts to determine the conformer ratios and energies in DMSO solvent to give Ecis-Etrans 1.1, -0.1 and 1.8 kcal/mol for (4), (5) and (6). Comparison of the observed versus calculated conformer energies show that both the MM and ab initio calculations overestimate the NH..F hydrogen bond in (4) by ca. 2 kcal/mol.

Design and synthesis of a hybrid series of potent and selective agonists of α7 nicotinic acetylcholine receptor.

α7 nicotinic acetylcholine receptor agonists are promising therapeutic candidates for the treatment of cognitive impairment. As a follow up of our internal medicinal chemistry program we investigated a novel series of α7 nAChR agonists. Starting from molecular docking studies on two series of molecules recently developed in our laboratories, an alternative scaffold was designed attempting to combine the optimal features of these previously identified urea and pyrazole compounds. Based on our previous SAR knowledge and on predicted drug-like properties, a small library was synthesized in parallel manner, affording compounds with excellent α7 nAChR activity, selectivity and preliminary ADME profile.

N-[5-(5-fluoropyridin-3-yl)-1H-pyrazol-3-yl]-4-piperidin-1-ylbutyramide (SEN78702, WYE-308775): a medicinal chemistry effort toward an α7 nicotinic acetylcholine receptor agonist preclinical candidate.

α7 Nicotinic acetylcholine receptors (α7 nAChR) represent promising therapeutic candidates for the treatment of cognitive impairment associated with Alzheimer's disease (AD) and schizophrenia. A medicinal chemistry effort around previously reported compound 1 (SEN15924, WAY-361789) led to the identification of 12 (SEN78702, WYE-308775) a potent and selective full agonist of the α7 nAChR that demonstrated improved plasma stability, brain levels, and efficacy in behavioral cognition models.

A homogeneous HTRF assay for the identification of inhibitors of the TWEAK-Fn14 protein interaction.

The TWEAK-Fn14 pathway is upregulated in models of inflammation, autoimmune diseases, and cancer. Both TWEAK and Fn14 show increased expression also in the CNS in response to different stimuli, particularly astrocytes, microglia, and neurons, leading to activation of NF-κB and release of proinflammatory cytokines. Although neutralizing antibodies against these proteins have been shown to have therapeutic efficacy in animal models of inflammation, no small-molecule therapeutics are yet available. Here, we describe the development of a novel homogeneous time-resolved fluorescence (HTRF)-based screening assay together with several counterassays for the identification of small-molecule inhibitors of this protein-protein interaction. Recombinant HIS-TWEAK and Fn14-Fc proteins as well as FLAG-TWEAK and Fn14-FLAG proteins and an anti-Fn14 antibody were used to establish and validate these assays and to screen a library of 60 000 compounds. Two HTRF counterassays with unrelated proteins in the same assay format, an antiaggregation assay and a redox assay, were applied to filter out potential false-positive compounds. The novel assay and associated screening cascade should be useful for the discovery of small-molecule inhibitors of the TWEAK-Fn14 protein interaction.

Design, synthesis and docking studies of Hydroxyethylamine and Hydroxyethylsulfide BACE-1 inhibitors.

Both stereoisomer of hydroxyethylamine (HEA) and hydroxyethylsulfide (HES) transition-state isostere inhibitors of BACE-1 were synthesized. The syn-HEA epimer resulted always more active than the anti stereoisomer independently from the P(1) and the P(1)' substituents. On the contrary, the anti epimer of the HES isostere resulted more active than the syn stereoisomer. The change of stereopreference was studied by molecular modelling.

Aryl azoles with neuroprotective activity--parallel synthesis and attempts at target identification.

A parallel synthesis of aryl azoles with neuroprotective activity is described. All compounds obtained were evaluated in an in vitro assay using a NMDA toxicity paradigm showing a neuroprotective activity between 15% and 40%. The potential biological target of the active compounds was investigated by extensive literature searches based around similar scaffolds with reported neuroprotective activity. The most interesting molecules active in the NMDA toxicity assay (3a and 2g) showed moderate but significant activity in the inhibition of the Site 2 Sodium Channel binding assay at 10 microM. To confirm our hypothesis compounds 3a, c, f and 2g were tested in the Veratridine assay which is one of the excitotoxicity assays of relevance to NaV channels. The compounds tested showed an activity between 40% and 70%. The identification of neuroprotective small molecules and the identification of NaV channels as the potential site of action were the most important goals of this work.