Acetic Anhydride → tert-butyl 3-[2-(acetyloxy)ethoxy]-5-amino-1-methyl-1H-pyrazole-4-carboxylate

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Reaction Steps

To tert-butyl 5-amino-3-(2-hydroxyethoxy)-1-methyl-1H-pyrazole-4-carboxylate (Preparation 11) (60 g) in tetrahydrofuran (500 ml), under nitrogen and at room temperature, was added triethylamine (41.7 ml), 4-dimethylaminopyridine (400 mg) followed by acetic anhydride (28.6 ml) dropwise. The reaction was stirred at room temperature overnight and was then concentrated under reduced pressure. The residue was diluted with ethyl acetate (300 ml) and washed with brine (2×100 ml). The organics were dried with magnesium sulfate, filtered and concentrated under reduced pressure to yield the desired product as white solid (71 g).

Provenance & Evidence