Thiazolo[4,5-d]pyrimidines. Part II. Synthesis and anti-human cytomegalovirus activity in vitro of certain acyclonucleosides and acyclonucleotides derived from the guanine analogue 5-aminothiazolo[4,5-d]pyrimidine-2,7(3H,6H)-dione

Synthesis, antifungal evaluation, and molecular docking studies of steroidal thiazolopyrimidines

A series of steroidal thiazolopyrimidine derivatives were developed and evaluated for their antifungal properties against Candida species using steroid as the basic skeletonand a thiazolopyrimidine heterocycle as a pharmacophore in the D-ring. Dehydroepiandrosterone, aromatic aldehydes, and 2-aminothiazole were used in a one-pot multicomponent reaction with silica sulphuric acid to generate the target molecules. Additionally, molecular docking studies were conducted to determine how synthesized steroidal derivatives interacted with the amino acid residues of CYP51 ofCandida albicans.

One-pot synthesis of thiazolo[3,2-a]pyrimidine derivatives, their cytotoxic evaluation and molecular docking studies

An economical, simple and efficient one-pot method has been developed for the synthesis of thiazolo[3,2-a]pyrimidine hydrobromide derivatives. 2,4-diaryl-6,7,8,9-tetrahydro-4H-benzo[4,5]thiazolo[3,2-a]pyrimidine hydrobromides were synthesized by the α-bromination of cyclohexanone with N-Bromosuccinamide (NBS) and followed by cyclization with 3,4-dihydropyrimidine-2(1H)-thiones, respectively, in the presence of p-toluenesulfonic acid (PTSA) in acetonitrile. However when cyclohexanone was replaced by acetyl acetone and alpha-tetralone gave the corresponding 1-(3-methyl-5,7-diaryl-5H-thiazolo[3,2-a]pyrimidin-2-yl)ethan-1-one hydrobromide and 9,11-diaryl-6,11-dihydro-5H-naphtho[1',2':4,5]thiazolo[3,2-a]pyrimidine hydrobromide derivatives, respectively. The significant features of this method are novel, simple, inexpensive experimental procedure, short reaction time, and good yield. The some of the synthesized compounds were evaluated for cytotoxic activity against human lung adenocarcinoma cell line (A549), human breast carcinoma cell line (MCF-7), human cervical cancer cell line (HeLa) and human neuronal carcinoma cell lines (SKNSH). Tested compounds 5(b-e) showed the excellent anticancer activity against various cell lines. Particularly compound 5c with IC₅₀ value of 2.2 ± 0.6 μM against A549 and compound 5e with IC₅₀ value of 5.6 ± 0.4 μM against HeLa showed best cytotoxic effects. Furthermore, Molecular docking study was performed for some of the synthesized compounds 5(b-e) against topoisomerase-II by using Auto dock method. Docking results of the compounds 5c, 5d, and 5e exhibited higher cytotoxic activity than the standard doxorubicin.

An expeditious four-component domino protocol for the synthesis of novel thiazolo[3,2-a]thiochromeno[4,3-d]pyrimidine derivatives as antibacterial and antibiofilm agents

An efficient domino protocol has been developed for the synthesis of new pyrimidine scaffolds, through a one-pot four-component cascade transformation via [Bmim]HSO4 ionic liquid mediated reaction, using an equimolar mixture of thiochroman-4-one, benzaldehyde, thiourea and 3-bromo-1-phenylpropan-1-one leading to the formation of a double electrophilic pyrimidine-2(5H)-thione intermediate. The intermediate regioselectively undergoes cyclization through intramolecular NH bond activation followed by CS bond formation leading to highly functionalized thiazolo[3,2-a]thiochromeno[4,3-d]pyrimidines. The ionic liquid operates efficiently under mild conditions. The recyclability and scope for recovery of the ionic liquid makes this protocol environmentally benign. Further, the compounds 5d, 5g and 5k showed promising antimicrobial activity against the tested Gram-positive bacterial strains. Among them, the compound 5d was identified as a lead molecule exhibiting promising anti-biofilm activity towards Staphylococcus aureus MTCC 96, Bacillus subtilis MTCC 121, Staphylococcus aureus MLS16 MTCC 2940 and Micrococcus luteus MTCC 2470 with IC50 values of 2.1, 1.9, 2.4 and 5.3μg/mL, respectively. Further, the compound 5d showed increased levels of intracellular ROS accumulation in Staphylococcus aureus MTCC 96 suggesting that oxidative stress resulted in bacterial cell lysis and death.

Androgen receptor antagonists and anti-prostate cancer activities of some newly synthesized substituted fused pyrazolo-, triazolo- and thiazolo-pyrimidine derivatives

A series of substituted pyrazole, triazole and thiazole derivatives (2–13) were synthesized from 1-(naphtho[1,2-d]thiazol-2-yl)hydrazine as starting material and evaluated as androgen receptor antagonists and anti-prostate cancer agents. The newly synthesized compounds showed potent androgen receptor antagonists and anti-prostate cancer activities with low toxicity (lethal dose 50 (LD₅₀)) comparable to Bicalutamide as reference drug. The structures of newly synthesized compounds were confirmed by IR, ¹H-NMR, ¹³C-NMR, and MS spectral data and elemental analysis. The detailed synthesis, spectroscopic data, LD₅₀ values and pharmacological activities of the synthesized compounds are reported.

Synthesis and anticancer evaluation of novel 3,5-diaryl-thiazolo[4,5-d]pyrimidin-2-one derivatives

The 2-oxo analogs of thiazolo[4,5-d]pyrimidine-2-thiones were prepared to study their cytotoxic activity. Five of the newly synthesized compounds were selected by the National Cancer Institute (Bethesda, MD, USA) for a primary in vitro antitumor assay. 7-Chloro-3,5-diphenyl-thiazolo[4,5-d]pyrimidin-2-one (5a) proved to be the most active one among the screened derivatives and was further evaluated in the full panel of 60 cell lines at five different concentrations. The structures of compounds were determined by IR, ¹H-NMR, ¹³C-NMR, X-ray, and elemental analysis.

Single-Step Syntheses of 2-Amino-7-chlorothiazolo[5,4-d]pyrimidines: Intermediates for Bivalent Thiazolopyrimidines

[reaction: see text] A single-step process for the preparation of 2-amino-7-chlorothiazolo[5,4-d]pyrimidines, 2, was achieved by the reaction of the commercially available 4,6-dichloro-5-aminopyrimidine 1 with isothiocyanates. This mild reaction accommodates a variety of functionalized isothiocyanates and proceeds in good to excellent yields. The utility of such intermediates is exemplified by subsequent reaction with alkyl or arylamine nucleophiles to afford novel, differentially functionalized 2,7-diaminothiazolo[5,4-d]pyrimidines, 3.