Abstract 2-(1H-Pyrazol-1-yl)-4-(4-nitrophenyl) thiazoles 2a and 2b, resulting from the condensation of 2-hydrazino-4-(4-nitrophenyl) thiazole (1) and acetylacetone and dibenzoylmethane, respectively, were previously [4] misas-signed as 3-(4-nitrophenyl) thiazolo [2, 3-c][1, 2, 4] triazepines 3a and 3b. The assignments were corrected by authentic syntheses of 2a and 2b from 2-chloro-5-(4-nitrophenyl) thiazole (6) and 3, 5-dimethyl-1H- ...