Large-scale solvent-free chlorination of hydroxy-pyrimidines, -pyridines, -pyrazines and -amides using equimolar POCl₃

3D-QSAR-based design, synthesis and biological evaluation of 2,4-disubstituted quinoline derivatives as antimalarial agents

2,4-Disubstituted quinoline derivatives were designed based on a 3D-QSAR study, synthesized and evaluated for antimalarial activity. A large dataset of 178 quinoline derivatives was used to perform a 3D-QSAR study using CoMFA and CoMSIA models. PLS analysis provided statistically validated results for CoMFA (r2ncv = 0.969, q2 = 0.677, r2cv = 0.682) and CoMSIA (r2ncv = 0.962, q2 = 0.741, r2cv = 0.683) models. Two series of a total of 40 2,4-disubstituted quinoline derivatives were designed with amide (quinoline-4-carboxamide) and secondary amine (4-aminoquinoline) linkers at the -C4 position of the quinoline ring. For the purpose of selecting better compounds for synthesis with good pEC50 values, activity prediction was carried out using CoMFA and CoMSIA models. Finally, a total of 10 2,4-disubstituted quinoline derivatives were synthesized, and screened for their antimalarial activity based on the reduction of parasitaemia. Compound #5 with amide linker and compound #19 with secondary amine linkers at the -C4 position of the quinoline ring showed maximum reductions of 64% and 57%, respectively, in the level of parasitaemia. In vivo screening assay confirmed and validated the findings of the 3D-QSAR study for the design of quinoline derivatives.

Synthesis and in vitro study of pyrimidine-phthalimide hybrids as VEGFR2 inhibitors with antiproliferative activity

Aim: Thalidomide, a once notorious sedative, is now clinically used as an antitumor agent. We aimed to use it as a lead compound for designing pyrimidine-phthalimide hybrids. Materials & methods: Nucleophilic substitution reaction of thalidomide analog 4 with primary and/or secondary aliphatic amines afforded pyrimidine-phthalimide hybrids 5a-g, 6 and 7a-d. Results & conclusion: Compound 7c showed high antiproliferative activity against four cell lines: HepG-2 (IC₅₀: 7.86 ± 0.5 μM), MCF-7 (IC₅₀: 2.77 ± 0.1 μM), HCT-116 (IC₅₀: 5.73 ± 0.4 μM) and PC-3 (IC₅₀: 8.32 ± 0.5 μM), with selective cytotoxicity for WI-38 (IC₅₀: 43.2 ± 2.56 μM). 7c arrested MCF-7 cells at S phase of the cell cycle and increased the total apoptotic cells by 50-fold. 7c inhibited VEGFR2 in vitro (IC₅₀: 0.130 ± 0.02 μM). 7c was capable of binding at the VEGFR2 binding site, forming hydrogen bond interactions with Asp1046 and Glu885 in a similar way to sorafenib.

New benzothienopyrimidine derivatives as dual EGFR/ARO inhibitors: Design, synthesis, and their cytotoxic effect on MCF-7 breast cancer cell line

New cytotoxic agents based on benzothienopyrimidine scaffold were designed, synthesized, and evaluated against the MCF-7 breast cancer line in comparison to erlotinib and letrozole as reference drugs. Eight compounds demonstrated up to 20-fold higher anticancer activity than erlotinib, and five of these compounds were up to 11-fold more potent than letrozole in MTT assay. The most promising compounds were evaluated for their inhibitory activity against EGFR and ARO enzymes. Compound 12, which demonstrated potent dual EGFR and ARO inhibitory activity with IC₅₀ of 0.045 and 0.146 µM, respectively, was further evaluated for caspase-9 activation, cell cycle analysis, and apoptosis. The results revealed that the tested compound 12 remarkably induced caspase-9 activation (IC₅₀  = 16.29 ng/ml) caused cell cycle arrest at the pre-G₁ /G₁ phase and significantly increased the concentration of cells at both early and late stage of apoptosis. In addition, it showed a higher safety profile on normal MCF-10A cells, and higher antiproliferative activity on cancer cells (IC₅₀  = 8.15 µM) in comparison to normal cells (IC₅₀  = 41.20 µM). It also revealed a fivefold higher selectivity index than erlotinib towards MCF-7 cancer cells. Docking studies were performed to rationalize the dual inhibitory activity of compound 12.

New benzothieno[2,3-c]pyridines as non-steroidal CYP17 inhibitors: design, synthesis, anticancer screening, apoptosis induction, and in silico ADME profile studies

A series of [1]benzothieno[2,3-c]pyridines was synthesised. Most compounds were chosen by NCI-USA to evaluate their anticancer activity. Compounds 5a-c showed prominent growth inhibition against most cell lines. 5c was selected at five dose concentration levels. It exhibited potent broad-spectrum anticancer activity with a GI50 of 4 nM-37 µM. Cytotoxicity of 5a-c was further evaluated against prostate, renal, and breast cancer cell lines. 5c showed double and quadruple the activity of staurosporine and abiraterone, respectively, against the PC-3 cell line with IC50 2.08 µM. The possible mechanism of anti-prostate cancer was explored via measuring the CYP17 enzyme activity in mice prostate cancer models compared to abiraterone. The results revealed that 5c suppressed the CYP17 enzyme to 15.80 nM. Moreover, it was found to be equipotent to abiraterone in testosterone production. Cell cycle analysis and apoptosis were performed. Additionally, the ADME profile of compound 5c demonstrated both good oral bioavailability and metabolic stability.

Synthesis of Isotopically Labeled (13)C3-Simazine and Development of a Simultaneous UPLC-MS/MS Method for the Analysis of Simazine in Soil

The isotope dilution mass spectrometry (IDMS) is a highly efficient method for tackling the ion suppression in complex matrix by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), but a lack of commercial internal standards is a limiting factor for these analyses. Herein, an economical and efficient strategy for the synthesis of ¹³C₃-simazine via a three-step procedure was developed. The isotope-labeled internal standard was used for determination of simazine residue in soil samples. The quantitation method has a limit of detection of 0.015 μg/kg and quantitation of 0.08 μg/kg. The inter-day and intra-day precision of the method were below 4.6%. Recovery values were ranged between 92.9% and 99.2%. All the samples obtained from six provinces in China contained from 1 to 62 μg/kg of simazine.

‘Green' Synthesis of 2-Substituted 6-Hydroxy-[3H]-pyrimidin-4-ones and 4,6-Dichloropyrimidines: Improved Strategies and Mechanistic Study

An improved route to 2-substituted 6-hydroxy-[3H]-pyrimidin-4-ones 4 and to 2-substituted 4,6-dichloropyrimidines 5 is reported. Without using highly toxic reactants, compounds 4 can be prepared conveniently in a one pot synthesis on a one mol scale with average yields up to 80 %. 4,6-Dichloropyrimidines 5, which are usually prepared in small quantities, are synthesized with average yields of 80 %, using up to 80 g of starting material. The mechanism of the chlorination of 4 is investigated computationally for the first time. The results suggest that the chlorination with phosphoryl chloride occurs in an alternating phosphorylation–chlorination manner (pathway 1) which is preferred over a sequence which starts with two phosphorylations. The investigated 4,6-dichloropyrimidines described herein form strong complexes with dichlorophosphoric acid but weak complexes with hydrochloric acid (generated during workup). These latter complexes explain the necessity of using aqueous sodium carbonate during the working up. In order to prevent possible formation of pyrimidinium salts between intermediates or the final dichloropyrimidines and unreacted hydroxypyrimidone, the latter could be deactivated with a strong acid such as dichlorophosphoric acid, thus allowing chlorination but prohibiting salt formation. Because of its general applicability to all nitrogen heterocycle chlorinations with phosphoryl chloride, the proposed route to dichloropyrimidines without solvent or side products, using less toxic reactants, is of general synthetic interest.