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Aberrant WNT pathway activation, leading to nuclear accumulation of β‐catenin, is a key oncogenic driver event. Mutations in the tumor suppressor gene APC lead to impaired proteasomal degradation of β‐catenin and subsequent nuclear translocation. Restoring cellular degradation of β‐catenin represents a potential therapeutic strategy. Here, we report the fragment‐based discovery of a small molecule binder to β‐catenin, including the structural elucidation of the binding mode by X‐ray crystallography. The difficulty in drugging β‐catenin was confirmed as the primary screening campaigns identified only few and very weak hits. Iterative virtual and NMR screening techniques were required to discover a compound with sufficient potency to be able to obtain an X‐ray co‐crystal structure. The binding site is located between armadillo repeats two and three, adjacent to the BCL9 and TCF4 binding sites. Genetic studies show that it is unlikely to be useful for the development of protein–protein interaction inhibitors but structural information and established assays provide a solid basis for a prospective optimization towards β‐catenin proteolysis targeting chimeras (PROTACs) as alternative modality., Targeting the armadillo repeat: We report the fragment‐based discovery of a small‐molecule binder to the key cancer target β‐catenin. Iterative virtual screening and ligand‐based NMR techniques enabled hit optimization in absence of structural information. The co‐crystal structure of a derivative in complex with a short β‐catenin variant revealed a novel small‐molecule binding site between armadillo repeats two and three.

A library of 24 6-(5-oxo-1-phenylpyrrolidin-3-yl)pyrimidine-5-carboxamides 10{1,2; 1–12} was prepared by a parallel solution-phase approach. The synthesis comprises a five-step transformation of itaconic acid (11) into 1-methyl and 1-phenyl substituted 6-(5-oxo-1-phenylpyrrolidin-3-yl)pyrimidine-5-carboxylic acids 17{1,2} followed by parallel amidation of 17{1,2} with a series of 12 aliphatic amines 18{1–12} to afford the corresponding carboxamides 10 in good overall yields and in 80–100% purity.

Phosphoglycerate dehydrogenase (PHGDH) is known to be the rate-limiting enzyme in the serine synthesis pathway in humans. It converts glycolysis-derived 3-phosphoglycerate to 3-phosphopyruvate in a co-factor-dependent oxidation reaction. Herein, we report the discovery of BI-4916, a prodrug of the co-factor nicotinamide adenine dinucleotide (NADH/NAD+)-competitive PHGDH inhibitor BI-4924, which has shown high selectivity against the majority of other dehydrogenase targets. Starting with a fragment-based screening, a subsequent hit optimization using structure-based drug design was conducted to deliver a single-digit nanomolar lead series and to improve potency by 6 orders of magnitude. To this end, an intracellular ester cleavage mechanism of the ester prodrug was utilized to achieve intracellular enrichment of the actual carboxylic acid based drug and thus overcome high cytosolic levels of the competitive cofactors NADH/NAD+.

1,5-Disubstituted-4-oxo-4,5-dihydro-1H-pyrazolo[4,3-c]pyridine-7-carboxamides functionalized at positions 1, 5, and 7 were prepared in six straightforward steps from cheap, commercially available dialkyl acetone-1,3-dicarboxylate. Due to the instability of methyl 1-benzyl-substituted pyrazolo[4,3-c]pyridine-7-carboxylates under basic hydrolytic conditions (LiOH/H2O), a detour via the corresponding benzyl esters was introduced to deliver the final 1-benzyl-substituted-bicyclic carboxamides in seven steps. The designed synthetic route is suitable for the construction of a larger library of compounds. All the key compounds have been characterized by NMR spectroscopic techniques and X-ray analysis.

The synthesis of 7-substituted pyrazolo[1,5-a]pyrimidine-3-carboxamides was studied. First, methyl 7-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylate (5) was prepared in three steps from methyl 5-amino-1H-pyrazole-4-carboxylate (3). Treatment of 5 with POCl3 gave the highly reactive 7-chloro derivative 10, which was reacted with amines, benzyl alcohol, and phenylboronic acid in the presence of Pd-catalyst to give the corresponding 7-substituted derivatives 11. Hydrolysis of the esters 5 and 11 followed by amidation gave the corresponding carboxamides 16a–h and 15. Regioselectivity of N-alkylation of 7-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylic acid derivatives 5 and 16 was tunable by the carboxy function. Alkylation of the secondary amides 16a–f furnished the 1-alkyl derivatives 17a–f, whereas the ester 5 and the tertiary amides 16g,h gave the 4-alkyl derivatives 14a–d and 16m,n, selectively.

A simple and practical four-step protocol for the parallel synthesis of 7-heteroaryl-pyrazolo[1,5- $$a$$ ]pyrimidine-3-carboxamides was developed. The synthesis starts with transformation of commercially available 2-acetylpyridine and acetylpyrazine with $$N,$$ $$N$$ -dimethylformamide dimethylacetal into the corresponding $$(E)$$ -3-(dimethylamino)-1-(heteroaryl)prop-2-en-1-ones followed by cyclisation with methyl 5-amino-1 $$H$$ -pyrazole-4-carboxylate to give methyl 7-heteroarylpyrazolo[1,5- $$a$$ ]pyrimidine-3-carboxylates. Hydrolysis of the ester group and subsequent amidation of the so formed carboxylic acids with 12 primary and secondary aliphatic amines furnished a library of 24 title compounds in good overall yields and purity.

A seven-step synthesis of 1-substituted 5-(2-acylaminoethyl)-1H-pyrazole-4-carboxamides 20 as the pyrazole analogues of histamine was developed. The synthesis starts with a three-step preparation of N(1)-substituted methyl 5-(2-tert-butoxycarbonylaminoethyl)-1H-pyrazole-4-carboxylates 7 from commercially available Boc-β-alanine (1). Subsequent four-step transformation of the key-intermediates 7 into the final products 20 was performed following two complementary reaction sequences comprising acidolytic removal of the Boc group, hydrolysis of the COOMe group, amidations of the COOH group, and acylations of the NH2 group. The structures of pyrazole derivatives were determined by spectroscopic methods and by X-ray diffraction.

A simple four-step synthesis of 4-(2-aminoethyl)-5-hydroxy-1H-pyrazoles 8 (or their 1H-pyrazol-3(2H)-one tautomers 8′) as the pyrazole analogues of histamine was developed. First, enamino lactam 3 was prepared as the key intermediate in two steps from 2-pyrrolidinone (1). Next, acid-catalysed ‘ring switching’ transformations of 3 with monosubstituted hydrazines 4 gave N-[(1-substituted 5-hydroxy-1H-pyrazol-4-yl)ethyl]benzamides 7a–k and N-[2-(2-heteroaryl-3-oxo-2,3-dihydro-1H-pyrazol-4-yl)ethyl]benzamides 7′l–o. Benzamides 7a–k and 7′l–o were finally hydrolysed by heating in 6 M hydrochloric acid to furnish 1-substituted 4-(2-aminoethyl)-5-hydroxy-1H-pyrazoles 8a–k and 4-(2-aminoethyl)-2-heteroaryl-1H-pyrazol-3(2H)-ones 8′l–o in good overall yields.

An uHTS campaign was performed to identify selective inhibitors of PKC-theta. Initial triaging of the hit set based on selectivity and historical analysis led to the identification of 2,4-diamino-5-nitropyrimidines as potent and selective PKC-theta inhibitors. A homology model and initial SAR is presented demonstrating that a 2-arylalkylamino substituent in conjunction with suitable 4-diamino substituent are essential for achieving selectivity over many kinases. Additional hit to lead profiling is presented on selected compounds.

Both epimers of the aldehyde 2 , a degradation product of muamvatin, have been synthesized in a streodefined manner. This allowed us to assign the relative and absolute configuration to muamvatin as shown in 19 . Key to this synthesis was a novel chiral building block 10 , representing the stereotriad D.

A highly selective series of bisbenzamide inhibitors of Rho-associated coiled-coil forming protein kinase (ROCK) and a related ureidobenzamide series, both identified by high throughput screening (HTS), are described. Details of the hit validation and lead generation process, including structure-activity relationship (SAR) studies, a selectivity assessment, target-independent profiling (TIP) results, and an analysis of functional activity using a rat aortic ring assay are discussed.

Highly effective sialic acid-containing inhibitors of influenza virus X-31 were synthesized using poly[N-(acryoyloxy)succinimide] (pNAS), a polymer preactivated by incorporation of active ester groups. Polymers containing two and three different components were prepared by sequential reaction of pNAS with two and three amines, respectively. This preparation of co- and terpolymers was synthetically more efficient than methods involving copolymerization of different monomers and gave polymers that were more easily compared than those generated by copolymerization. Polymers in this study (prepared from a single batch of pNAS) had a constant degree of polymerization (DP approximately 2000) and probably had a distribution of components that was more random than analogous polymers prepared by copolymerization. Use of C-glycosides of sialic acid made it possible to investigate inhibition by different polymers at temperatures ranging from 4 to 36 degrees C without artifacts due to the hydrolytic action of neuraminidase. The inhibitors were, in general, more effective at 36 degrees C than at 4 degrees C. The hemagglutination (HAI) assay was used to measure the value of the inhibition constant KHAIi each polymer. The value of KHAIi for the two-component polymer containing 20% sialic acid on a polyacrylamide backbone at 4 degrees C was 4 nM (in terms of the sialic acid moieties present in solution) and was approximately 50-fold more effective than the best inhibitors previously described and 25-fold more effective than the best naturally occurring inhibitor. The most effective inhibitor synthesized in this work contained 10% benzyl amine and 20% sialic acid on a polyacrylamide backbone, and its value of KHAIi was 600 pM at 36 degrees C. Approximately 100 polymers that differed in one or two components were assayed to distinguish between two limiting mechanisms for inhibition of the interaction between the surfaces of virus and erythrocytes: high-affinity binding through polyvalency, and steric stabilization. The results suggest that both mechanisms play an important role. The system comprising polyvalent inhibitors of agglutination of erythrocytes by influenza provides a system that may be useful as a model for inhibitors of other pathogen-host interactions, a large number of which are themselves polyvalent.