Discovery of 4-anilino-N-methylthieno[3,2-d]pyrimidines and 4-anilino-N-methylthieno[2,3-d]pyrimidines as potent apoptosis inducers

We report the discovery of N-((benzo[d][1,3]dioxol-5-yl)methyl)-6-phenylthieno[3,2-d]pyrimidin-4-amine (2a) as an apoptosis inducer using our proprietary cell- and caspase-based ASAP HTS assay, and SAR study of HTS hit 2a which led to the discovery of 4-anilino-N-methylthieno[3,2-d]pyrimidines and 4-anilino-N-methylthieno[2,3-d]pyrimidines as potent apoptosis inducers. Compounds 5d and 5e were the most potent with EC₅₀ values of 0.008 and 0.004 μM in T47D human breast cancer cells, respectively. Compound 5d was found to be highly active in the MX-1 breast cancer model. Functionally, compounds 5d and 5e both induced apoptosis through inhibition of tubulin polymerization.     

Discovery of 3,6-dihydro-2H-pyran as a morpholine replacement in 6-aryl-1H-pyrazolo[3,4-d]pyrimidines and 2-arylthieno[3,2-d]pyrimidines: ATP-competitive inhibitors of the mammalian target of rapamycin (mTOR)

The morpholine hinge-region binding group on a series of pyrazolopyrimidine and thienopyrimidine mammalian target of rapamycin (mTOR) inhibitors was replaced with 3,6-dihydro-2H-pyran (DHP), giving compounds of equivalent potency and selectivity versus PI3K. These results establish the DHP group as a hinge-region binding motif for the preparation of highly potent and selective mTOR inhibitors.     

Pyrazolo[3,4-d]pyrimidines containing an extended 3-substituent as potent inhibitors of Lck -- a selectivity insight

A series of para-substituted 3-phenyl pyrazolopyrimidines was synthesized and evaluated as inhibitors of lck. The nature of the substitution affected enzyme selectivity and potency for lck, src, kdr, and tie-2. The para-phenoxyphenyl analogue 2 is an orally active lck inhibitor with a bioavailability of 69% and exhibits an extended duration of action in animal models of T cell inhibition.     

3D-QSAR studies on thieno[3,2-d]pyrimidines as phosphodiesterase IV inhibitors

Cyclic nucleotide phosphodiesterase IV (PDE IV) inhibitors find utility in asthma and Chronic Obstructive Pulmonary Disease (COPD) therapy. A series of 29 thieno[3,2-d]pyrimidines with affinity for PDE IV was subjected to three dimensional quantitative structure activity relationship (3D-QSAR) studies using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). Both CoMFA and CoMSIA provided statistically valid models with good correlative and predictive power. The incorporation of hydrophobic, hydrogen bond donor and hydrogen bond acceptor fields showed insignificant improvement in CoMSIA model. The 3D-QSAR models provide information for predicting the affinity of related compounds and designing more potent inhibitors.     

2-Arylureidophenyl-4-(3-oxa-8-azabicyclo[3.2.1]octan-8-yl)triazines as highly potent and selective ATP competitive mTOR inhibitors: Optimization of human microsomal stability

Isosteric replacement of one of the 3,5-ethylene-bridged morpholines in 2-arylureidophenyl-4,6-di(3-oxa-8-azabicyclo[3.2.1]octan-8-yl)triazines led to significant improvements in human microsomal stability. 3-R-Me-morpholine and tetrahydropyran were identified as preferred isosteres for the bridged morpholine. Combination of tetrahydropyran substitution with an N-Me-piperazinophenylureido group led to 27, that selectively suppressed mTOR biomarkers in vivo and possessed excellent efficacy in a murine xenograft model.     

Pyrrolo[2,3-d]pyrimidines containing diverse N-7 substituents as potent inhibitors of Lck

A series of pyrrolo[2,3-d]pyrimidines was synthesized and evaluated as inhibitors of Lck. Lck accommodates a diverse set of substituents at N-7. Altering the substituent at N-7 provided compound 13, an orally available lck inhibitor which inhibited TCR mediated IL-2 production after oral dosing.     

Discovery and optimization of thieno[2,3-d]pyrimidines as B-Raf inhibitors

The serine/threonine specific protein kinase B-Raf is part of the MAPK pathway and is an interesting oncology target. We have identified thieno[2,3-d]pyrimidines as a core scaffold of small molecule B-Raf inhibitors. The SAR of analogs in this series will be described.     

Discovery of novel 8-azoniabicyclo[3.2.1]octane carbamates as muscarinic acetylcholine receptor antagonists

In the course of our research program to develop novel muscarinic receptor antagonists for the treatment of COPD, new tropane carbamate derivatives were identified as potent anti-muscarinic agents. The synthesis, structure-activity relationships and pharmacological evaluation that led to the identification of compound 5o, are described.     

Rational design of 4-amino-5,6-diaryl-furo[2,3-d]pyrimidines as potent glycogen synthase kinase-3 inhibitors

4-Amino-5,6-diaryl-furo[2,3-d]pyrimidines have been identified as inhibitors of glycogen synthase kinase-3beta (GSK-3beta). One representative derivative, 4-amino-3-(4-(benzenesulfonylamino)-phenyl)-2-(3-pyridyl)-furo[2,3-d]pyrimidine (12) exhibited potent GSK-3beta inhibitory activity in low nanomolar level of IC(50). The binding mode was proposed from a docking study.     

Synthesis and biological activity of thieno[3,2-d]pyrimidines as potent JAK3 inhibitors for the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a serious and fatal lung disease, with a median survival of only 3–5 years from diagnosis. Janus kinase 3 (JAK3) has a well-established role in the pathogenesis of various autoimmune diseases, including rheumatoid arthritis (RA) and autoimmune-related pulmonary fibrosis. In this study, through the use of a conformationally-constrained design strategy, a series of thieno[3,2-d]pyrimidines were synthesized as potent JAK3 inhibitors for the treatment of IPF. Among them, the most potent JAK3 inhibitor, namely 8e (IC₅₀ = 1.38 nM), significantly reduced the degree of airsacculitis and fibrosis according to hematoxylin-eosin (HE) staining assay for the lung tissue in the bleomycin (BLM)-induced pulmonary fibrosis mouse model. The clear reduction of the lung collagen deposition by the determination of Masson and hydroxyproline (HYP) content also demonstrated its efficacy in the treatment of fibrosis. In addition, 8e also reduced the expression of the inflammatory markers IL-6, IL-17A, TNF-α and malondialdehyde (MDA) in lung tissue, which indicated its higher anti-inflammatory activity compared with that of the reference agents (nintedanib and gefitinib). Furthermore, it possessed low cytotoxicity against normal human bronchial epithelia (HBE) cells (IC₅₀ > 39.0 μM) and C57BL mice. All these evaluated biological properties suggest that 8e may be a potential JAK3 inhibitor for the treatment of IPF.     

Development of substituted pyrido[3,2-d]pyrimidines as potent and selective dihydrofolate reductase inhibitors for pneumocystis pneumonia infection

Pneumocystis pneumonia (PCP) caused by Pneumocystis jirovecii (pj) can lead to serious health consequences in patients with an immunocompromised system. Trimethoprim (TMP), used as first-line therapy in combination with sulfamethoxazole, is a selective but only moderately potent pj dihydrofolate reductase (pjDHFR) inhibitor, whereas non-clinical pjDHFR inhibitors, such as, piritrexim and trimetrexate are potent but non-selective pjDHFR inhibitors. To meet the clinical needs for a potent and selective pjDHFR inhibitor for PCP treatment, fourteen 6-substituted pyrido[3,2-d]pyrimidines were developed. Comparison of the amino acid residues in the active site of pjDHFR and human DHFR (hDHFR) revealed prominent amino acid differences which could be exploited to structurally design potent and selective pjDHFR inhibitors. Molecular modeling followed by enzyme assays of the compounds revealed 15 as the best compound of the series with an IC₅₀ of 80 nM and 28-fold selectivity for inhibiting pjDHFR over hDHFR. Compound 15 serves as the lead analog for further structural variations to afford more potent and selective pjDHFR inhibitors.     

Identification of pyrrolo[2,3-d]pyrimidines as potent HCK and FLT3-ITD dual inhibitors

A series of novel pyrrolo[2,3-d]pyrimidines were synthesized by introducing 15 different amino acids to 7-cyclohexyl-5-(4-phenoxyphenyl)-7H-pyrrolo[2,3-d]pyrimidine-4-amine. Compounds with potent activities against HCK and FLT3-ITD were evaluated in viability studies with acute myeloid leukemia cell line MV4-11. Our structure activity relationship analyses lead to the identification of compound 31, which exhibited potent HCK and FLT3-ITD inhibition and activity against the MV4-11 cell line.     

Synthesis and anticancer activities of thieno[3,2-d]pyrimidines as novel HDAC inhibitors

A series of thieno[3,2-d]pyrimidines bearing a hydroxamic acid moiety as novel HDAC inhibitors were designed and synthesized. The structures of the new synthesized compounds were confirmed using IR, ¹H, ¹³C NMR spectrum. Compounds 11–13 showed potent inhibitory activities against HDACs with IC₅₀ values at 0.38, 0.49 and 0.61 μM. Most of target compounds displayed strong anti-proliferative activity by a MTT assay on three human cancer cell lines including HCT-116, MCF-7 and HeLa. Compound 11, having potent inhibitory activities against HDACs, induced apoptosis and G2/M cell cycle arrest in HCT-116 cell line.     

Pyrrolo[2,3-d]pyrimidines containing an extended 5-substituent as potent and selective inhibitors of lck II

Pyrrolo[2,3-d]pyrimidines containing a 5-(4-phenoxyphenyl) substituent are novel, potent and selective inhibitors of lck in vitro. Exploration of C-6 position of the pyrrolo[2,3-d]pyrimidine and the terminal phenyl group structure-activity relationship (SAR) is detailed. Compound 1 is orally active in animal models.     

Dual EGFR/ErbB-2 inhibitors from novel pyrrolidinyl-acetylenic thieno[3,2-d]pyrimidines

A novel class of substituted pyrrolidinyl-acetylenic thieno[3,2-d]pyrimidines has been identified that are potent and selective inhibitors of both EGFR/ErbB-2 receptor tyrosine kinases. The inhibitors are found to display a range of enzyme and cellular potency and also to display a varying level of covalent modification of the kinase targets. Selected molecules, including compound 15h, were found to be potent in enzymatic and cellular assays while also demonstrating exposure in the mouse from an oral dose.     

Pyrrolo[2,3-d]pyrimidines containing an extended 5-substituent as potent and selective inhibitors of lck I

Pyrrolo[2,3-d]pyrimidines containing a 5-(4-phenoxyphenyl) substituent are potent and selective inhibitors of Ick in vitro; some compounds are selective for lck over src. Data are shown for two compounds demonstrating that they are potent and selective inhibitors of IL2 production in cells.     

Synthesis and stereochemical effects of pyrrolidinyl-acetylenic thieno[3,2-d]pyrimidines as EGFR and ErbB-2 inhibitors

A novel class of pyrrolidinyl-acetyleneic thieno[3,2-d]pyrimidines has been identified which potently inhibit the EGFR and ErbB-2 receptor tyrosine kinases. Synthetic modifications of the pyrrolidine carbamate moiety result in a range of effects on enzyme and cellular potency. In addition, the impact of the absolute stereochemical configuration on cellular potency and oral mouse pharmacokinetics is described.     

Novel 4-amino-furo[2,3-d]pyrimidines as Tie-2 and VEGFR2 dual inhibitors

A novel class of furo[2,3-d]pyrimidines has been discovered as potent dual inhibitors of Tie-2 and VEGFR2 receptor tyrosine kinases (TK) and a diarylurea moiety at 5-position shows remarkably enhanced activity against both enzymes. One of the most active compounds, 4-amino-3-(4-((2-fluoro-5-(trifluoromethyl)phenyl)amino-carbonylamino)phenyl)-2-(4-methoxyphenyl)furo[2,3-d]pyrimidine (7k) is <3 nM on both TK receptors and the activity is rationalized based on the X-ray crystal structure.     

4-Acylamino-6-arylfuro[2,3-d]pyrimidines: potent and selective glycogen synthase kinase-3 inhibitors

Modeling studies of a furo[2,3-d]pyrimidine GSK-3 hit compound 1 superimposed onto the X-ray crystal structure of a legacy pyrazolo[3,4-c]pyridazine GSK-3 inhibitor 2 led to the identification of 4-acylamino-6-arylfuro[2,3-d]pyrimidine template 3. Synthesis of analogues based on template 3 has resulted in a number of potent and selective GSK-3beta inhibitors. The most potent and selective compound was the m-pyridyl analogue 24.     

Identification and SAR of a new series of thieno[3,2-d]pyrimidines as Tpl2 kinase inhibitors

We report here the synthesis and SAR of a new series of thieno[3,2-d]pyrimidines as potent Tpl2 kinase inhibitors. The proposed binding mode suggests the potential flipped binding mode depending on the substitution. Biacore studies show evidence of binding of these molecules to the protein kinase. The kinome inhibition profile of these molecules suggests good selectivity.