Synthesis of Novel Fluorinated 1H-Pyrazole-1-carbothioamide and 5(1H-Pyrazol-1-yl)thiazoles Containing 1,5-Diphenyl-1H-1,2,3-Triazole Moiety

The current work reports the synthesis of novel fluorinated 1H-pyrazole-1-carbothioamide and 5-(1H-pyrazol-1-yl)thiazoles containing 1,5-diphenyl-1H-1,2,3-triazole moiety. The synthetic procedures were simple, efficient, involved few steps, and led to high yields of the designed products. The reaction of 1-(1,5-diphenyl-1H-1,2,3-triazol-4-yl)ethanone (1) and 4-flurobenzaldehyde in ethanol in the presence of a base at room temperature gave 1-(1,5-diphenyl-1H-1,2,3-triazol-4-yl)-3-(4-fluorophenyl) prop-2-en-1-one (2) in a 87% yield. The reaction of 2 and excess hydrazine hydrate in boiling ethanol afforded 4-(5-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-3-yl)-1,5-diphenyl-1H-1,2,3-triazole (3) in a 82 % yield. The treatment of 3 with phenylisothiocyanate furnished 3-(1,5-diphenyl-1H-1,2,3-triazol-4-yl)-5-(4-fluorophenyl)-N-phenyl-4,5-dihydro-1H-pyrazole-1-carbothioamide (4) in 90% yields. On the other hand, the reaction of 2 and thiosemicarbazide gave 3-(1,5-diphenyl-1H-1,2,3-triazol-4-yl)-5-(4-fluorophenyl)4,5-dihydro-1H-pyrazole-1-carbothioamide (5). The reaction of 5 and a number of 1-aryl-2-bromoethanones provided the corresponding 2-(3-(1,5-diphenyl-1H-1,2,3-triazol-4-yl)-5-(4-fluorophenyl)-4,5-dihydro1H-pyrazol-1-yl)-4-arylthiazoles 6a-d in 80-86%. The structures of products 2-6 were elucidated using element content analysis, nuclear magnetic resonance, and X-ray crystal structures.