Systematic structural modifications of indolealkylphenylpiperazines led to improved selectivity and affinity within this class of 5-HT(1A) receptor agonists. Introduction of electron-withdrawing groups in position 5 on the indole raises serotonin transporter affinity, and the cyano group proved to be the best substituent here. 5-Fluoro and 5-cyano substituted indoles show comparable results in in vitro and in vivo tests, and bioisosterism between these substituents was supported by calculation of the molecular electrostatic potentials and dipole moments. Compounds showing promising in vitro data were further examined in ex vivo (p-chloroamphetamine assay) and in vivo (ultrasonic vocalization) tests. Optimization of the arylpiperazine moiety indicated that the 5-benzofuranyl-2-carboxamide was best suited to increase 5-HT transporter and 5-HT(1A) receptor affinity and to suppress D(2) receptor binding. 5-[4-[4-(5-Cyano-3-indolyl)butyl]-1-piperazinyl]benzofuran-2-carboxamide 29 (vilazodone, EMD 68843) was identified as a highly selective 5-HT(1A) receptor agonist [GTPgammaS, ED(50) = 1.1 nM] with subnanomolar 5-HT(1A) affinity [IC(50) = 0.2 nM] and as a subnanomolar 5-HT reuptake inhibitor [RUI = 0.5 nM] showing a great selectivity to other GPCRs (e.g., D(2), IC(50) = 666 nM).

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Focal adhesion kinase (FAK) is considered as an attractive target for oncology, and small-molecule inhibitors are reported to be in clinical testing. In a surface plasmon resonance (SPR)-mediated fragment screening campaign, we discovered bicyclic scaffolds like 1H-pyrazolo[3,4-d]pyrimidines binding to the hinge region of FAK. By an accelerated knowledge-based fragment growing approach, essential pharmacophores were added. The establishment of highly substituted unprecedented 1H-pyrrolo[2,3-b]pyridine derivatizations provided compounds with submicromolar cellular FAK inhibition potential. The combination of substituents on the bicyclic templates and the nature of the core structure itself have a significant impact on the compounds FAK selectivity. Structural analysis revealed that the appropriately substituted pyrrolo[2,3-b]pyridine induced a rare helical DFG-loop conformation. The discovered synthetic route to introduce three different substituents independently paves the way for versatile applications of the 7-azaindole core.

Targeting allosteric protein sites is a promising approach to interfere selectively with cellular signaling cascades. We have discovered a novel class of allosteric insulin-like growth factor-I receptor (IGF-1R) inhibitors. 3-Cyano-1H-indole-7-carboxylic acid {1-[4-(5-cyano-1H-indol-3-yl)butyl]piperidin-4-yl}amide (10) was found with nanomolar biochemical, micromolar, cellular IGF-1R activity and no relevant interference with cellular insulin receptor signaling up to 30 μM. The allosteric binding site was characterized by X-ray crystallographic studies, and the structural information was used to explain the unique mode of action of this new class of inhibitors.

The mechanism of photosensitized nucleophilic substitution reactions on arylcyclopropanes was investigated. Stereochemical experiments with methanol, water, and cyanide as nucleophiles showed that the reactions occurred stereospecifically with complete inversion of configuration at the carbon atom undergoing substitution. Independent generation of the arylcyclopropane cation radicals by nanosecond transient methods showed that they reacted rapidly with nucleophiles with kinetics that were first-order in both the cation radical and the nucleophiles. Through a combination of transient kinetics and steady-state Stern−Volmer quenching experiments, the reaction of the phenylcyclopropane cation radical with methanol was kinetically correlated with the formation of the substitution product. The reaction of phenylcyclopropane cation radical with a series of alcohols as nucleophiles showed small steric effects.

Co-and post-translational processing are crucial maturation steps to generate functional proteins. MetAP-2 plays an important role in this process, and inhibition of its proteolytic activity has been shown to be important for angiogenesis and tumor growth, suggesting that small-molecule inhibitors of MetAP-2 may be promising options for the treatment of cancer. This work describes the discovery and structurebased hit optimization of a novel MetAP-2 inhibitory scaffold. Of critical importance, a cyclic tartronic diamide coordinates the MetAP-2 metal ion in the active site while additional side chains of the molecule were designed to occupy the lipophilic methionine side chain recognition pocket as well as the shallow cavity at the opening of the active site. The racemic screening hit from HTS campaign 11a was discovered with an enzymatic IC 50 of 150 nM. The resynthesized eutomer confirmed this activity and inhibited HUVEC proliferation with an IC 50 of 1.9 μM. Its structural analysis revealed a sophisticated interaction pattern of polar and lipophilic contacts that were used to improve cellular potency to an IC 50 of 15 nM. In parallel, the molecular properties were optimized on plasma exposure and antitumor efficacy which led to the identification of advanced lead 21.

A series of new 1-[4-(indol-3-yl)butyl]-4-arylpiperazines was prepared to identify highly selective and potent 5-HT(1A) agonists as potential pharmacological tools in studies of mood disorders. The combination of structural elements (indole-alkyl-amine and aryl-piperazine) known to introduce 5-HT(1A) receptor affinity and the proper selection of substituents (R on the indole moiety and R' on the aryl moiety) led to compounds with high receptor specificity and affinity. In particular, the introduction of the methyl ether or the unsubstituted carboxamide as substituents in position 5 of the indole (R) guaranteed serotonergic 5-HT(1A) affinity compared to the unsubstituted analogue. Para-substituted arylpiperazines (R') decreased dopaminergic D(2) binding and increased selectivity for the 5-HT(1A) receptor. Agonistic 5-HT(1A) receptor activity was confirmed in vivo in the ultrasonic vocalization test, and the results suggest that the introduction of the carboxamide residue leads to better bioavailability than the corresponding methyl ether. 3-[4-[4-(4-Carbamoylphenyl)piperazin-1-yl]butyl]-1H-indole-5-carboxamide 54 was identified as a highly selective 5-HT(1A) receptor agonist [GTPgammaS, ED(50) = 4.7 nM] with nanomolar 5-HT(1A) affinity [IC(50) = 0.9 nM] and selectivity [D(2), IC(50) > 850 nM]. 3-[4-[4-(4-Methoxyphenyl)piperazin-1-yl]butyl]-1H-indole-5-carboxamide 45 is one of the most potent and selective 5-HT(1A) agonists known [5-HT(1A), IC(50) = 0.09 nM; D(2), IC(50) = 140 nM].

The recently disclosed next generation of reversible, selective, and potent MetAP-2 inhibitors introduced a cyclic tartronic diamide scaffold. However, the lead compound 1a suffered from enterohepatic circulation, preventing further development. Nevertheless, 1a served as a starting point for further optimization. Maintaining potent antiproliferation activity, while improving other compound properties, enabled the generation of an attractive array of new MetAP-2 inhibitors. The most promising derivatives were identified by a multiparameter analysis of the compound properties. Essential for the efficient selection of candidates with in vivo activity was the identification of molecules with a long residence time on the target protein, high permeability, and low efflux ratio not only in Caco-2 but also in the MDR-MDCK cell line. Orally bioavailable, potent, and reversible MetAP-2 inhibitors impede the growth of primary endothelial cells and demonstrated antitumoral activity in mouse models. This assessment led to the nomination of the clinical development compound M8891, which is currently in phase I clinical testing in oncology patients.