Selected Methodologies Convenient for the Synthesis of N,5‐Diaryloxazole‐2‐amine Pharmacophore

N,5‐Diaryloxazole‐2‐amine moiety is a strong pharmacophore found in 775 biologically active compounds possessing antitumor, anti‐infective, immunosuppressive, anti‐inflammatory, and other activities. Despite a broad biological exploitation, synthesis of N,5‐diaryloxazole‐2‐amine‐containing compounds is still not well developed. Preparation of oxazole‐2‐amine moiety is a relatively complex topic, and often low yields are observed. In this article, we discussed four synthetic methodologies and provided some generalization of their advantages, as well as further synthetic development. Using these methodologies, we prepared all together 10 new oxazole‐2‐amine derivatives and discovered presence of urea and enamine side products.     

Microwave Induced Synthesis of 3‐Aryl‐6‐(6‐/8‐substituted 4‐chloroquinoline‐3‐yl) ‐ s ‐triazolo [3,4‐b] −1,3,4‐thiadiazoles

The condensation of 4‐amino‐3‐aryl‐5‐mercapto‐1, 2, 4‐triazoles (1a‐f) with 6‐/8‐substituted 1,4‐dihydro‐4‐oxo‐quinoline‐3‐carboxylic adds (2a‐d) in the presence of phosphorus oxychloride on refluxng or under microwave irradiation gave twenty four novel 3‐aryl‐6‐ (6‐/8‐substituted 4‐chloroquinoline‐3‐yl)‐s‐triazolo[3,4‐b]‐1, 3,4‐thiadiazoles (4a‐x), Considerable increase in the reaction rate has been observed with improved yields under microwave irradiation. The structures of the compounds synthesized were determined by elemental analyses, IR, ¹H NMR and MS spectra. Their spectral properties and the reaction mechanism were also discussed. The preliminary biological test showed that some of compounds bad moderate antibacterial activities.