In 1959,Graner, R. Franquesa published 《Synthesis of 2-acetamido-5-nitrothiazole, an oral bactericide》.Galenica Acta published the findings.Application In Synthesis of Methyl 1H-pyrazole-3-carboxylate The information in the text is summarized as follows:
Tech. 2-aminothiazole-HCl was purified by neutralizing with NaOH at 50°, cooling with the addition of the solid amine to prevent supercooling, washing at pH 11-12, then with a saturated solution of NaCl, and then H2O. The solid was air-dried and distilled, b12 139-43°; 65% 2-aminothiazole (I) was recovered. Preparation of 2-acetamido-5-nitrothiazole (II) (CA 46, 10285h; 40, 40583) was accomplished by acetylation, then nitration of I (78.2% over-all yield), and by the reverse steps (62.8% over-all). Ac2O (1.3 mole), 1 mole I, and 0.1 mole H2SO4 was refluxed 10 min., poured on ice, and the solid recrystallized m. 209-10°, for a 92% yield of 2-acetamidothiazole (III). III (142 g.) was dissolved in 450 ml. concentrated H2SO4 at 10° with the addition of 46 ml. (d. 1.5) fuming HNO3 over 40 min.; allowing the temperature to reach 50° for 30 min., pouring on ice, filtering, and washing with water, EtOH, and recrystallizing from AcOH (50 ml./5 g.) gave 152 g. II, m. 265-6°. I (100 g.) was dissolved in 300 ml. concentrated H2SO4 at 10°, and 46 ml. (d. 1.5) fuming HNO3 was added dropwise with agitation at 12°. The temperature was kept 3 hrs. at 0°, then at 25° for 24 hrs. The mass was poured onto 5000 ml. icewater, and the filtrate neutralized with 600 g. Na2CO3 in 2000 ml. H2O. The product was water-washed, and recrystallized from EtOH (100 ml./5 g.) to give 100 g. 2-amino-5-nitrothiazole (IV), m. 202-3°. IV (7 g.), 50 ml. Ac2O, and 3 drops of concentrated H2SO4 were refluxed 7 min., and cooled to 0°. Recrystallization of the solid from AcOH gave 8.5 g. II, m. 265°. In the experiment, the researchers used Methyl 1H-pyrazole-3-carboxylate(cas: 15366-34-4Application In Synthesis of Methyl 1H-pyrazole-3-carboxylate)
Methyl 1H-pyrazole-3-carboxylate(cas: 15366-34-4) belongs to pyrazoles. The application of pyrazole derivatives in the development of anticancer agents has been thoroughly investigated and verified. Moreover, the medicinal features of a number of natural products incorporating pyrazole moiety such as pyrazofurin, pyrazofurin B, pyrazole-3(5)-carboxylic acid and 4-methylpyrazole-3(5)-carboxylic acid have been reported.Application In Synthesis of Methyl 1H-pyrazole-3-carboxylate
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics