Dichloromethane → Allyl 3,5-diamino-1H-pyrazole-4-carboxylate

Participants

Reaction Steps

To a suspension of allyl 3-amino-4,4,4-trichloro-2-cyano-but-2-enoate 2 (619 g, 2.297 mol) and KOAc (676.3 g, 6.891 mol) in DMF (2.476 L) at 0° C. was slowly added hydrazine hydrate (172.5 g, 167.6 mL, 3.446 mol) over 15 min. The reaction mixture was then stirred at ambient temperature for 2 h, at which stage 1H NMR shows complete consumption of the starting material. Reaction mixture was then heated overnight at 110° C. before being allowed to cool to ambient and stirred for another 48 h. The mixture was filtered through a sintered glass funnel to remove the precipitated solid and the filtrate was evaporated under reduced pressure to give a thick liquid. DCM (approx 2 L) was added and the mixture filtered again to remove additional solids that have precipitated. The filtrate was purified through a 1 kg silica gel plug (gradient of DCM/MeOH as an eluent) and the solvent was removed to afford an orange solid which was suspended in acetonitrile and heated at about 70° C. until all the solid went into solution, at which point the solution was allowed to cool to ambient temperature, then to 2° C. The precipitate that formed was isolated by filtration under vacuum, washed with chilled MeCN (˜50 mL) and dried to constant mass in a vacuum oven to furnish the title compound as an off-white powder (171.2 g, 41%).

Provenance & Evidence