Electric Literature of 138786-86-4, The chemical industry reduces the impact on the environment during synthesis 138786-86-4, name is Methyl 4-nitro-1H-pyrazole-3-carboxylate, I believe this compound will play a more active role in future production and life.
3,4-dihydropyran (8.21 ml, 90 mmol) was added drop wise to a solution of 4-nitro- lH-pyrazole-3-carboxylic acid methyl ester (10 g, 60 mmol) in chloroform (200 ml) at O0C. The reaction mixture was stirred for 45 min before being allowed to warm to 250C. After 1 h Et2O (100 ml) was added and this mixture was washed sequentially with sat. aq. NaHCO3 (250 ml), water (2 x 250 ml), and brine (250 ml). The organics were dried (Na2SO4) and evaporated in vacuo to give 4-nitro-l-(tetrahydro-pyran-2- yl)-lH-pyrazole-3-carboxylic acid methyl ester as a yellow oil (16.99g, impure). A portion of this protected pyrazole (9.66 g, 37.88 mmol) was combined with hydrazine hydrate (9.97 ml, 200 mmol) and ethanol (150 ml) and stirred at 250C under N2. After Ih the mixture was evaporated in vacuo to give a crude orange oil. This was partitioned between EtOAc (4 x 150 ml) and brine (150 ml). The organic layer was dried (Na2SO4) and evaporated in vacuo to give 4-nitro-l-(tetrahydro-pyran-2-yl)- lH-pyrazole-3-carboxylic acid hydrazide as a yellow foam (8.45 g, 87%). (LC/MS (acidic method): Rt 1.56, [M+H]+256).
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