Trimethyl orthoformate → N-(2-Acetylphenyl)-5-fluoro-1,3-dimethyl-1H-pyrazole-4-carboxamide

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Reaction Steps

14 g (80% pure, 33.6 mmol) of 5-fluoro-N-[2-(1-hydroxy-1,3-dimethylbutyl)phenyl]-1,3-dimethyl-1H-pyrazole-4-carboxamide and 4.28 g (40.3 mmol) of trimethyl orthoformate are dissolved in 420 ml of toluene, and 5 drops of concentrated sulphuric acid are added. The solution is boiled for 1 h, treated with sodium sulphate and filtered off, and the filtrate is concentrated under reduced pressure. The residue is treated with 300 ml of heptane. This results in the N-(2-acetylphenyl)-5-fluoro-1,3-dimethyl-1H-pyrazole-4-carboxamide still present in the starting material precipitating out. The filtrate is concentrated using a rotary evaporator, giving 10.7 g of a yellow oil. Examination by GC/MS shows the following composition: 24% A, 25% B, 29% C and 7% of a methanol adduct.

Provenance & Evidence