6-BROMO-3-PHENYL-1H-INDAZOLE synthesis

Yield:885271-16-9 42%

Reaction Conditions:

Stage #1: (4-bromo-2-aminophenyl)phenyl-methanonewith hydrogenchloride;sodium nitrite in water at 0; for 0.55 h;
Stage #2: with hydrogenchloride;tin(ll) chloride in water at 0 - 20; for 1.16667 h;
Stage #3: with sodium hydroxide in water;

Steps:

112.a

EXAMPLE 112; 2,2-Dimethyl-3-phenyl-3-(3-phenyl-lH-indazol-6-yl)-N-(thiazol-2- yl)propanamide; (a) To a stirred mixture of (2-amino-4-bromophenyl)(phenyl)methanone (1.0 g, 3.6 mmol) in hydrochloric acid (6N aqueous solution, 5 mL) was added sodium nitrite (0.5 g, 7.2 mmol) over 3 min at 0⁰C. The mixture was stirred at 0⁰C for 30 min before a solution of tin(II) chloride (2.7 g, 14.4 mmol in 5 mL concentrated hydrochloric acid) was added at 0⁰C over 5 min. After stirring at 0⁰C for 10 min and rt for 1 hr, the reaction mixture was filtered. The solid was washed with water (10 mL), 4N aqueous sodium hydroxide solution, and water (10 mL). The solid was dissolved in dichloromethane (20 mL), washed with brine (10 mL), dried (Na₂SO₄), and concentrated. Silica gel flash chromatography gave 6-bromo-3 -phenyl- IH- indazole (0.42 g, 1.5 mmol, 42% yield).

References:

WO2008/57856,2008,A2 Location in patent:Page/Page column 123