反应详情

3′-Amino-2′-hydroxy-biphenyl-3-carboxylic acid hydrobromide 1f (155 mg, 0.5 mmol) was dissolved in 1.7 mL of hydrochloric acid (1 N) followed by dropwise addition of 0.6 mL of aqueous sodium nitrite (36 mg, 0.53 mmol) and the mixture was stirred for 10 minutes upon cooling by an ice-water bath. Then 2-(2,3-dihydro-benzofuran-5-yl)-5-methyl-2,4-dihydro-pyrazol-3-one 7c (97 mg, 0.45 mmol) was added. The mixture was adjusted to pH 7 by batch addition of saturated aqueous sodium bicarbonate (630 mg, 7.5 mmol). The reaction mixture was warmed up to room temperature overnight. The reaction was monitored by TLC until the disappearance of the starting materials. The mixture was adjusted to pH<5 with concentrated hydrochloric acid. The mixture was filtered and dried to obtain the title compound 3′-{N′-[1-(2,3-dihydro-benzofuran-5-yl)-3-methyl-5-oxo-1,5-dihydro-pyrazol-4-ylidene]-hydrazino}-2′-hydroxy-biphenyl-3-carboxylic acid 7 (131 mg, yield 63.9%) as a brown solid.

1. temperatureupon cooling by an ice-water bath
2. filtrationThe mixture was filtered
3. customdried