Novel one-pot four-component condensation cyclization reactions for the synthesis of thiazolidine-4-one and 3<i>H</i>-thiazoles

<p>A novel, simple and efficient synthetic protocol has been developed for the synthesis of a series of thiazolidine-4-one and 3<i>H</i>-thiazole derivatives <i>via</i> a one-pot four-component condensation-cyclization reaction of hydrazine with allyl isothiocyanate and an α-haloketone in the presence of various aldehydes. This new protocol produces novel thiazolidine-4-one and 3<i>H</i>-thiazole derivatives in excellent yields. The remarkable features of this methodology are high yields, easy work-up and a one-pot simple reaction method.</p

Synthesis and evaluation of biological activities of 4-cyclopropyl-5-(2-fluorophenyl) arylhydrazono-2,3-dihydrothiazoles as potent antioxidant agents

<p>A new series of 4-cyclopropyl-5-(2-fluorophenyl)arylhydrazono-2,3-dihydrothiazole derivatives was synthesized via the reaction of prepared thiosemicarbazones with 2-bromo-1-cyclopropyl-2-(2-fluorophenyl)ethanone in the presence of Et₃N as a catalyst through a semi Hantzsch cyclization. The optimized reaction conditions for this one-pot reaction were achieved. The products were obtained in short reaction times, high yields and high purities. Antioxidant activity of products was evaluated using DPPH (2,2-diphenyl-2-picrylhydrazyl) and ABTS 2,2-azinobis(3-ethylbenzothiazoline-sulfonate) assays. Products showed higher antioxidant activity using the ABTS method. Compounds <b>5c</b> and <b>5g</b> showed lower IC₅₀ values compared with ascorbic acid as a standard. Compounds <b>5a–5h</b> possessed moderate to high antioxidant activity by both methods. Also, antibacterial activity of <b>5a–5h</b> was evaluated against gram-positive and gram-negative bacterial strains. None of the compounds inhibited <i>A. hydrophila</i>, while they had moderate to low inhibitory activity against other tested bacterial strains.</p

Novel, One-Pot, Three-Component, Regioselective Synthesis of Fluorine-Containing Thiazole and Bis-3<i>H</i>-thiazole Derivatives Using Polyvinyl Pyridine as Heterogeneous Catalyst, and Evaluation of Their Antibacterial Activity

<div><p></p><p>A convenient, one-pot, three-component regioselective synthesis of novel 2,2′-(1,4-phenylene)-bis-(3-aryl-2-substituted imino-4-aryl-3H-thiazole) derivatives from 1,4-phenylene diisothiocyanate, aryl amines, and various phenacyl bromide, and also the regioselective synthesis of 3-alkyl-2-(aryl imino)-4-cyclopropyl-5-(2′-fluorophenyl)-thiazole derivatives from alkylisothiocyanate, aryl amines, and 2-bromo-2-(2-fluorophenyl)-1-cyclopropylethanone in the presence of poly-4-vinyl pyridine as heterogenous basic catalyst are described. This efficient method produced the products at room temperature with excellent yields (82–96%). The structures of all products were characterized by spectral and elemental analyses. The antimicrobial activity of the synthesized compounds was evaluated against <i>Salmonella enterica, Micrococcus luteus, Bacillus subtilis</i>, and <i>Pseudomonas aeruginosa</i>.</p></div