methyl 4-(4-chlorophenyl)-2,4-dioxobutanoate → methyl 1-[4-(aminosulfonyl)phenyl]-5-(4-chlorophenyl)-1H-pyrazole-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

A 100 mL round-bottomed flask equipped with magnetic stirrer and nitrogen inlet was charged with methyl 4-[4-(chloro)phenyl]-2,4-dioxobutanoate from Step 1 (5.0 g, 20.78 mmol), 4-sulfonamidophenylhydrazine hydrochloride (5.11 g, 22.86 mmol) and methanol (50 mL). The reaction vessel was heated to reflux and held for 16 hours. A precipitate formed overnight. The suspension was cooled to 0° C., held for 0.5 hour, filtered and washed with cold water to provide, after air-drying, 7.91 g (91%) of crude product. Recrystallized 3.50 g from boiling ethanol to yield 3.14 g (97% of pure methyl (1-(4-aminosulfonylphenyl)-5-(4-chlorophenyl)-1H-pyrazole-3-yl]carboxylate: mp 227° C.; 1H NMR (CDCl3/300 MHz); 7.91 (d, J=8.86 Hz, 2H), 7.44 (d, J=8.86 Hz, 2H), 7.33 (d, J=8.66 Hz, 2H), 7.14 (d, J=8.66 Hz, 2H), 7.03 (s, 1H), 3.96 (s, 3H). Mass Spectrum, MH+=392. Anal. Calc'd for C17H14N3O4ClS: C, 52.11; H, 3.60; N, 10.72; Cl, 9.05; S, 5.18. Found: C, 52.07; H, 3.57; N, 10.70; Cl, 9.11; S, 8.27.

Provenance & Evidence