These common heterocyclic compound, 31037-02-2, name is Ethyl 5-amino-1-methyl-1H-pyrazole-4-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. category: pyrazoles-derivatives
A solution of ethyl 5-amino-1-methyl-4-pyrazole carboxylate (42.2 g, 0.25 mol) in THF is treated with NaH (60% in mineral oil, 25.2 g, 0.75 mol), stirred for 30 min, treated with ethyl 3-methoxy-3-[(trifluoromethyl)phenyl]-2-propenoate (65.5 g, 0.25 mol), heated at reflux temperature for 36 h, cooled to 0 C., acidified to pH 5 with aqueous HCl and extracted with EtOAc. The extracts are combined, washed with brine, dried over Na2SO4 and concentrated in vacuo. The resultant off-white solid residue is triturated with hexanes to give a white solid. The solid is dissolved in phosphorus oxychloride (750 mL) and heated to reflux temperature for 2 h, cooled to room temperature and concentrated. This concentrate is dissolved in EtOAc, cooled to 0 C., and neutralized with aqueous Na2CO3. The organic phase is separated, washed with brine, dried over Na2SO4 and concentrated. This resultant residue is chromatographed on silica gel (3:1 hexanes:EtOAc) to afford the title compound as a white solid 65% (68% yield), characterized by H-NMR and mass spectral analyses.
The synthetic route of Ethyl 5-amino-1-methyl-1H-pyrazole-4-carboxylate has been constantly updated, and we look forward to future research findings.
Reference:
Patent; Wyeth; US2004/24008; (2004); A1;,
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics