Novel library synthesis of 3,4-disubstituted pyridin-2(1H)-ones via cleavage of pyridine-2-oxy-7-azabenzotriazole ethers under ionic hydrogenation conditions at room temperature.

In our hands, efficient access to the 4-amino-3-carboxamide disubstituted pyridine-2(1H)-one kinase hinge-binder motif proved to be more challenging than anticipated requiring a significant investment in route scouting and optimization. This full paper focuses on the synthesis issues that we encountered during our route exploration and the original solutions we found that helped us to identify two optimized library-style processes to prepare our large kinase inhibitor library.

Squaramides as novel class I and IIB histone deacetylase inhibitors for topical treatment of cutaneous t-cell lymphoma.

A series of squaramide-based hydroxamic acids were designed, synthesized and evaluated against human HDAC enzyme. Squaramides were found to be potent in the Hut78 cell line, but initially suffered from low solubility. Leads with improved solubility and metabolic profiles were shown to be class I, IIB and IV selective.

Translation of innovative chemistry into screening libraries: an exemplar partnership from the European Lead Factory.

The identification of high-quality starting points for drug discovery is an enduring challenge in medicinal chemistry. Yet, the chemical space explored in discovery programmes tends be limited by the narrow toolkit of robust methods that are exploited in discovery workflows. The European Lead Factory (ELF) was established in 2013 to boost early-stage drug discovery within Europe. In this Feature, we describe an exemplar partnership that has led to the addition of 21119 distinctive screening compounds to the ELF Joint European Compound Library. The partnership could serve as a blueprint for the translation of innovative academic chemistry into discovery programmes.

Realisation of small molecule libraries based on frameworks distantly related to natural products.

The availability of high-quality screening compounds is of paramount importance for the discovery of innovative new medicines. Natural product (NP) frameworks can inspire the design of productive compound libraries. Here, we describe the design and synthesis of four compound libraries based on scaffolds that have broad NP-like features, but that are only distantly related to specific NPs. The optimisation of syntheses of the scaffolds using [5 + 2] cycloaddition chemistry is detailed, together with methods to yield exemplar decorated screening compounds. In each case, a library was nominated for production, leading to a total of >2900 screening compounds that augmented the Joint European Compound Library of the European Lead Factory.

Discovery of a series of 8-(1-phenylpyrrolidin-2-yl)-6-carboxamide-2-morpholino-4H-chromen-4-one as PI3Kß/δ inhibitors for the treatment of PTEN-deficient tumours.

Attempts to lock the active conformation of compound 4, a PI3Kß/δ inhibitor (PI3Kß cell IC50 0.015µM), led to the discovery of a series of 8-(1-phenylpyrrolidin-2-yl)-6-carboxamide-2-morpholino-4H-chromen-4-ones, which showed high levels of potency and selectivity as PI3Kß/δ inhibitors. Compound 10 proved exquisitely potent and selective: PI3Kß cell IC50 0.0011µM in PTEN null MDA-MB-468 cell and PI3Kδ cell IC50 0.014µM in Jeko-1 B-cell, and exhibited suitable physical properties for oral administration. In vivo, compound 10 showed profound pharmacodynamic modulation of AKT phosphorylation in a mouse PTEN-null PC3 prostate tumour xenograft after a single oral dose and gave excellent tumour growth inhibition in the same model after chronic oral dosing. Based on these results, compound 10 was selected as one of our PI3Kß/δ preclinical candidates.

A metal-catalyzed enyne-cyclization step for the synthesis of bi- and tricyclic scaffolds amenable to molecular library production.

A facile metal-catalyzed diversification step for the synthesis of novel bi- and tricyclic scaffolds from enyne substrates is reported in this study. From a single starting material, topologically diverse scaffolds for library synthesis can be generated and decorated in a few steps. The methodology was used to produce a library of 490 compounds within the European Lead Factory (ELF) Consortium.

Discovery of a series of 8-(2,3-dihydro-1,4-benzoxazin-4-ylmethyl)-2-morpholino-4-oxo-chromene-6-carboxamides as PI3Kß/δ inhibitors for the treatment of PTEN-deficient tumours.

We report the discovery and optimisation of a series of 8-(2,3-dihydro-1,4-benzoxazin-4-ylmethyl)-2-morpholino-4-oxo-chromene-6-carboxamides, leading to compound 16 as a potent and selective PI3Kß/δ inhibitor: PI3Kß cell IC50 0.012 µM (in PTEN null MDA-MB-468 cell) and PI3Kδ cell IC50 0.047 µM (in Jeko-1 B-cell), with good pharmacokinetics and physical properties. In vivo, 16 showed profound pharmacodynamic modulation of AKT phosphorylation in a mouse PTEN-deficient PC3 prostate tumour xenograft after a single oral dose and gave excellent tumour growth inhibition in the same model after chronic oral dosing. Compound 16 was selected as a preclinical candidate for the treatment of PTEN-deficient tumours.

Discovery of 1-(4-(5-(5-amino-6-(5-tert-butyl-1,3,4-oxadiazol-2-yl)pyrazin-2-yl)-1-ethyl-1,2,4-triazol-3-yl)piperidin-1-yl)-3-hydroxypropan-1-one (AZD8835): A potent and selective inhibitor of PI3Kα and PI3Kδ for the treatment of cancers.

Starting from potent inhibitors of PI3Kα having poor general kinase selectivity (e.g., 1 and 2), optimisation of this series led to the identification of 25, a potent inhibitor of PI3Kα (wild type, E545K and H1047R mutations) and PI3Kδ, selective versus PI3Kß and PI3Kγ, with excellent general kinase selectivity. Compound 25 displayed low metabolic turnover and suitable physical properties for oral administration. In vivo, compound 25 showed pharmacodynamic modulation of AKT phosphorylation and near complete inhibition of tumour growth (93% tumour growth inhibition) in a murine H1047R PI3Kα mutated SKOV-3 xenograft tumour model after chronic oral administration at 25mg/kg b.i.d. Compound 25, also known as AZD8835, is currently in phase I clinical trials.

Expansion of chemical space for collaborative lead generation and drug discovery: the European Lead Factory Perspective.

High-throughput screening (HTS) represents a major cornerstone of drug discovery. The availability of an innovative, relevant and high-quality compound collection to be screened often dictates the final fate of a drug discovery campaign. Given that the chemical space to be sampled in research programs is practically infinite and sparsely populated, significant efforts and resources need to be invested in the generation and maintenance of a competitive compound collection. The European Lead Factory (ELF) project is addressing this challenge by leveraging the diverse experience and know-how of academic groups and small and medium enterprises (SMEs) engaged in synthetic and/or medicinal chemistry. Here, we describe the novelty, diversity, structural complexity, physicochemical characteristics and overall attractiveness of this first batch of ELF compounds for HTS purposes.

Investigation of (E)-3-[4-(2-Oxo-3-aryl-chromen-4-yl)oxyphenyl]acrylic Acids as Oral Selective Estrogen Receptor Down-Regulators.

A novel estrogen receptor down-regulator, 7-hydroxycoumarin (5, SS5020), has been reported with antitumor effects against chemically induced mammary tumors. Here, we report on our own investigation of 7-hydroxycoumarins as potential selective estrogen receptor down-regulators, which led us to the discovery of potent down-regulating antagonists, such as 33. Subsequent optimization and removal of the 7-hydroxy group led to coumarin 59, which had increased potency and improved rat bioavailability relative to SS5020.

Synthesis of 1,4,5 trisubstituted γ-lactams via a 3-component cascade reaction.

A three component one-pot cascade reaction was developed for the synthesis of 1,4,5-trisubstituted γ-lactams. The resulting scaffold can be modified independently at three positions, two of which are conveniently accessed by changing the components of the one-pot reaction. The phases of building block generation, scaffold synthesis and subsequent appendage modification were adapted to library production, which resulted in a screening library of 500 compounds.

Design, synthesis and decoration of molecular scaffolds for exploitation in the production of alkaloid-like libraries.

The design, synthesis and decoration of six small molecule libraries is described. Each library was inspired by structures embedded in the framework of specific alkaloid natural products. The development of optimised syntheses of the required molecular scaffolds is described, in which reactions including Pd-catalysed aminoarylation and diplolar cycloadditions have been exploited as key steps. The synthesis of selected exemplar screening compounds is also described. In five cases, libraries were subsequently nominated for production on the basis of the scope and limitations of the validation work, as well as predicted molecular properties. In total, the research has led to the successful synthesis of >2500 novel alkaloid-like compounds for addition to the screening collection (the Joint European Compound Library, JECL) of the European Lead Factory.

Discovery of (R)-8-(1-(3,5-difluorophenylamino)ethyl)-N,N-dimethyl-2-morpholino-4-oxo-4H-chromene-6-carboxamide (AZD8186): a potent and selective inhibitor of PI3Kß and PI3Kδ for the treatment of PTEN-deficient cancers.

Several studies have highlighted the dependency of PTEN deficient tumors to PI3Kß activity and specific inhibition of PI3Kδ has been shown activity against human B-cell cancers. We describe the discovery and optimization of a series of 8-(1-anilino)ethyl)-2-morpholino-4-oxo-4H-chromene-6-carboxamides as PI3Kß/δ inhibitors, which led to the discovery of the clinical candidate 13, also known as AZD8186. On the basis of the lower lipophilicity of the chromen-4-one core compared to the previously utilized pyrido[1,2-a]pyrimid-4-one core, this series of compounds displayed high metabolic stability and suitable physical properties for oral administration. Compound 13 showed profound pharmacodynamic modulation of p-Akt in PTEN-deficient PC3 prostate tumor bearing mice after oral administration and showed complete inhibition of tumor growth in the mouse PTEN-deficient PC3 prostate tumor xenograft model. 13 was selected as a clinical candidate for treatment of PTEN-deficient cancers and has recently entered phase I clinical trials.

Discovery of 9-(1-anilinoethyl)-2-morpholino-4-oxo-pyrido[1,2-a]pyrimidine-7-carboxamides as PI3Kß/δ inhibitors for the treatment of PTEN-deficient tumours.

Starting from TGX-221, we designed a series of 9-(1-anilinoethyl)-2-morpholino-4-oxo-pyrido[1,2-a]pyrimidine-7-carboxamides as potent and selective PI3Kß/δ inhibitors. Structure-activity relationships and structure-property relationships around the aniline and the amide substituents are discussed. We identified compounds 17 and 18, which showed profound pharmacodynamic modulation of phosphorylated Akt in the PC3 prostate tumour xenograft, after a single oral dose. Compound 17 also gave significant inhibition of tumour growth in the PC3 prostate tumour xenograft model after chronic oral dosing.

Discovery of new quinoline ether inhibitors with high affinity and selectivity for PDGFR tyrosine kinases.

A new series of quinoline ether inhibitors, which potently and selectively inhibit PDGFR tyrosine kinases, is described in this Letter. Compounds 23 and 33 are selective, low nanomolar inhibitors of PDGFRα and ß, display good pharmacokinetics in rat and dog and are active in vivo at low doses when given orally twice daily. Further evaluation of these compounds is warranted.

Discovery of AZD2932, a new Quinazoline Ether Inhibitor with high affinity for VEGFR-2 and PDGFR tyrosine kinases.

A new series of Quinazoline Ether Inhibitor which potently inhibits VEGFR-2 and PDGFR tyrosine kinases is described here. In vitro, pharmacokinetics and in vivo evaluations led to the selection of AZD2932.

Imidazole piperazines: SAR and development of a potent class of cyclin-dependent kinase inhibitors with a novel binding mode.

A piperazine series of cyclin-dependent kinase (CDK) inhibitors have been identified. The compounds exhibit excellent physiochemical properties and a novel binding mode, whereby a bridging interaction via a water molecule with Asp 86 of CDK2, leads to selectivity for the CDK family of enzymes over other kinases. Piperazines 2e and 2i were subsequently shown to inhibit tumour growth when dosed orally in a nude mouse xenograft study. Additional chemical series that exploit this unexpected interaction with Asp 86 are also described.

N-(5-chloro-1,3-benzodioxol-4-yl)-7-[2-(4-methylpiperazin-1-yl)ethoxy]-5- (tetrahydro-2H-pyran-4-yloxy)quinazolin-4-amine, a novel, highly selective, orally available, dual-specific c-Src/Abl kinase inhibitor.

Src family kinases (SFKs) are nonreceptor tyrosine kinases that are reported to be critical for cancer progression. We report here a novel subseries of C-5-substituted anilinoquinazolines that display high affinity and specificity for the tyrosine kinase domain of the c-Src and Abl enzymes. These compounds exhibit high selectivity for SFKs over a panel of recombinant protein kinases, excellent pharmacokinetics, and in vivo activity following oral dosing. N-(5-Chloro-1,3-benzodioxol-4-yl)-7-[2-(4-methylpiperazin-1-yl)ethoxy]-5-(tetrahydro-2H-pyran-4-yloxy)quinazolin-4-amine (AZD0530) inhibits c-Src and Abl enzymes at low nanomolar concentrations and is highly selective over a range of kinases. AZD0530 displays excellent pharmacokinetic parameters in animal preclinically and in man (t(1/2) = 40 h). AZD0530 is a potent inhibitor of tumor growth in a c-Src-transfected 3T3-fibroblast xenograft model in vivo and led to a significant increase in survival in a highly aggressive, orthotopic model of human pancreatic cancer when dosed orally once daily. AZD0530 is currently undergoing clinical evaluation in man.

Inhibitors of epidermal growth factor receptor tyrosine kinase: Novel C-5 substituted anilinoquinazolines designed to target the ribose pocket.

A series of novel C-5 substituted anilinoquinazolines, selected on the basis of docking experiments and overlays with ATP in the active site of EGFR tyrosine kinase, have been prepared and found to be potent inhibitors. In vivo pharmacokinetics and disease model activity are discussed.