4-(Methylsulfonyl)phenylhydrazine hydrochloride → 6-methoxy-2-[1-(4-methylsulfonylphenyl)-3-trifluoromethyl-1H-pyrazol-5-yl]benzothiazole

Participants

Reaction Steps

The mixture of 4,4,4-trifluoro-1-(6-methoxybenzothiazol-2-yl)butane-1,3-dione (300 mg, 1.0 mmol) and 4-methylsulfonyl-phenylhydrazine hydrochloride (260 mg, 1.1 mmol) was heated under reflux in ethanol (50 ml) for 3.5 hours, and then allowed to cool. The precipitated crystals were collected and subjected to recrystallization from ethanol and ethyl acetate-isooctane to afford 6-methoxy-2-[1-(4-methylsulfonylphenyl)-3-trifluoromethyl-1H-pyrazol-5-yl]benzothiazole (350 mg, 77%). NMR(CDCl3) δ: 3.11 (3H, s), 3.89 (3H, s), 7.11 (1H, dd, J=2.3 Hz, 8.6 Hz), 7.20 (1H, s), 7.32 (1H, d, J=2.3 Hz), 7.75 (2H, d, J=8.6 Hz), 7.82 (1H, d, J=8.6 Hz), 8.04 (2H, d, J=8.6 Hz); mp 217-218° C.

Provenance & Evidence