Synthetic Route of 138786-86-4, These common heterocyclic compound, 138786-86-4, name is Methyl 4-nitro-1H-pyrazole-3-carboxylate, its traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route.
PART I: Synthesis Scheme I, shows that 4-nitro-1H-pyrazole-3-carboxylic acid (compound 12) was alkylated with methyl iodide in the presence of potassium carbonate in DMF. After flash chromatography on silica gel, two regioisomers, alkyl 1-alkyl-4-nitro-1H-pyrazole-3-carboxylate (compound 13a, 1,3-isomer) and alkyl 1-alkyl-4-nitro-1H-pyrazole-5-carboxylate (compound 13b, 1,5-isomer) were obtained in 26% and 74% yield, respectively. The structures of the isomers (compounds 13a, 13b) were determined by NOESY analysis: a NOESY correlation was observed between H-5 and alkyl protons in compound 13a.16 The nitro group of compounds 13a and 13b was reduced by hydrogenation in the presence of a catalytic amount of catalytic amount of 10% Pd/C to produce amines compounds 14a and 14b, respectively. Cyclization of compound 14b with urea afforded compound 15. Chlorination of compound 15 with POCl3 and DIPEA in toluene afforded compound 16 in 68% yield. Treatment with appropriate substituted anilines in isopropanol with 1 drop of conc. HCl with compound 16, provided the instant compounds 4-11 of this invention (65-78% yields).
The synthetic route of 138786-86-4 has been constantly updated, and we look forward to future research findings.
Reference:
Patent; Duquesne University of the Holy Spirit; Gangjee, Aleem; (26 pag.)US2019/276457; (2019); A1;,
Pyrazole – Wikipedia,
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