Sulfuric Acid → HCID 135800031, compound

Participants

Reaction Conditions

Reaction Steps

Ethyl 6-amino-3-chloroindazol-1-ylacetate (11.5 g) was warmed with 35% sulphuric acid to obtain a solution. Ice (54 g) was added and the solution cooled to -5° C. in an ice/salt bath. A solution of sodium nitrite (4 g) in water (43cm3) was added slowly with stirring and cooling at 0° C. When addition was complete, the mixture was stirred for 15 minutes at 0° C. A pre-cooled solution (5° C.) of cupric nitrate (173 g) in water (1.6L) was added with stirring and cooling at 5° C. Cooper (I) oxide (6.5 g) was added and the mixture stirred at 0° C. for 0.5 hours, after which it was allowed to warm to room temperature for 4.5 hours. The reaction mixture was extracted with ethyl acetate (×4) and the combined organic phase washed with water, dried (MgSO4), filtered and the solvent removed from the filtrate under vacuum. The residue was stirred with ethanol (400cm3) saturated with hydrogen chloride overnight, evaporated under vacuum and then partitioned between water and ethyl acetate. The organic phase was washed with water, dried (MgSO4), filtered and the solvent removed from the filtrate under vacuum. The residue was purified by flash chromatography (SiO2 ; chloroform:ether,3:2) to give ethyl 3-chloro-6-hydroxyindazol-1-ylacetate (4.34 g) as a brown solid; recrystallised from toluene, m.pt 138°-142° C.

Provenance & Evidence