Efficient Synthesis of New Functionalized 2-(Hetaryl)thiazoles

Synthesis of New Binary Thiazole-Based Heterocycles and Their Molecular Docking Study as COVID-19 Main Protease (Mpro) Inhibitors

Isolated polynuclear binary heterocyclic compounds containing thiazole building block combined with benzofuran, pyrrole, thiazole, or thiophene via carboxamide and/or secondary amine as a junction are presented. The synthetic strategy of those is based on utilization of 2-chloroacetamido-4-phenylthiazole in the synthesis of binary heterocyclic compounds by cyclocondensation with salicylic aldehyde, acetonitrile derivatives, ammonium thiocyanate, 3-mercaptoacrylonitrile derivatives, and/or 3-mercaptoacrylate derivatives. The prepared binary thiazole-based heterocycles have been studied as protease (M^pro) inhibitors by molecular docking for visualization of their orientation and interactions with COVID-19 units using hydroxychloroquine as a reference molecule.

Synthesis, Antibacterial and Antitubercular Activities of Some 5H-Thiazolo[3,2-a]pyrimidin-5-ones and Sulfonic Acid Derivatives

A series of 5H-thiazolo[3,2-a]pyrimidin-5-ones were synthesized by the cyclization reactions of S-alkylated derivatives in concentrated H₂SO₄. Upon treatment of S-alkylated derivatives at different temperatures, intramolecular cyclization to 7-(substituted phenylamino)-5H-thiazolo[3,2-a]pyrimidin-5-ones or sulfonation of cyclized products to sulfonic acid derivatives occurred. The structures of the target compounds were confirmed by IR, ¹H-NMR, ¹³C-NMR and HRMS studies. The compounds were evaluated for their preliminary in vitro antibacterial activity against some Gram-positive and Gram-negative bacteria and screened for antitubercular activity against Mycobacterium tuberculosis by the broth dilution assay method. Some compounds showed good antibacterial and antitubercular activities.

An Efficient Synthesis of Novel Dihydrothiazol-2-yl-amides via Cyclisation of Propargylic Carbamothioyl-amides

An efficient protocol is described for the versatile synthesis of novel dihydrothiazol-2-yl-amide derivatives via the regioselective 5-exo-dig heterocyclisation of N-propargyl carbamothioyl-amides in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) in refluxing ethanol. All products were obtained in good yields and short reaction time (10–30 min).

Synthesis of Pyrazolylthiazole and Pyrazolyl-1,2,4-Triazepine Derivatives

In a multistep reaction, ( Z)-methyl 2-[( Z)-2-hydrazono-4-oxo-]-(3-substituted-1 H-pyrazol-5-yl)thiazolidin-5-ylidine)acetate, ( Z)-methyl-1-(2-methoxy-2-oxoethyl)-2-[( Z)-5-(2-methoxy-2-oxoethylidene)-4-oxo-3-(3-substituted-1 H-pyrazol-5-yl)-thiazolidin-2-ylidine)hydrazinecarboxylates and methyl 5-oxo-4-(3-substituted-1 H-pyrazol-5-yl)-3-thioxo-3,4,5,6-tetrahydro-2 H-1,2,4-triazepine-7-carboxylates have been formed in good yield from the reaction of N-(3-substituted-1 H-pyrazol-5-yl)-hydrazinecarbothioamides with dimethyl acetylenedicarboxylate. Explanations of these conversions involving nucleophilic reactions and condensations are presented.