Methyl iodide → 5-bromo-3-iodo-1-methyl-1H-indazole

Participants

Reaction Conditions

Reaction Steps

A solution of 184.30 g of 5-bromo-3-iodo-1H-indazole [459133-66-5] in 2500 ml of methanol is admixed at 40° C. with 212 ml of a sodium methoxide solution (5.4M in methanol). 90 ml of methyl iodide are then added and the reaction mixture is heated to 65° C. After 30 minutes, the reaction mixture is cooled to room temperature, concentrated by evaporation to approx. 1000 ml, diluted with water and extracted with ethyl acetate (2×). The combined organic phases are dried over sodium sulphate and concentrated by evaporation. The title compound is obtained as a dark brown solid from the residue by means of flash chromatography (SiO2 60 F). Rf=0.68 (dichloromethane). Rt=4.94 (gradient I). As a by-product, the 5-bromo-3-iodo-2-methyl-2H-indazole regioisomer is also isolated as a red-orange solid. Rf=0.52 (dichloromethane). Rt=4.58 (gradient I).

Provenance & Evidence