2-Bromo-1-(1H-pyrazol-4-yl)ethanone: Versatile Precursor for Novel Mono- and Bis[pyrazolylthiazoles]

Abstract

The synthesis of novel bis(thiazoles) 20a, 20b, 20c and 23a, 23b, 23c is reported. Thus, reaction of 2-bromo-1-(5-methyl-1-phenyl-1H-pyrazol-4-yl)ethanone (6) with the corresponding thioamide derivatives 7a,7b, in refluxing EtOH in the presence of triethylamine, afforded 4-pyrazolylthiazoles 8a, 8b in good yields. On the other hand, the novel bis(thiazoles) 20a, 20b, 20c and 23a, 23b, 23c were obtained from the reaction of 6 with the corresponding benzaldehyde thiosemicarbazones 19a, 19b, 19c, 22a, 22b, 22c in refluxing EtOH. Compounds 19a, 19b, 19c and 22a, 22b, 22c were obtained by condensation of the corresponding bis(aldehydes) 18a, 18b, 18c and 21a, 21b, 21c with thiosemicarbazide.