5-bromo-1H-indazole → 5-Bromo-2-methyl-2H-indazole

Participants

Reaction Steps

Add at room temperature under nitrogen, trimethyloxonium tetrafluoroborate (229.34; g, 1.52; mol) portion wise to a mixture of 5-bromo-1H-indazole (199.6; g, 1.01 mol) in ethyl acetate (3.04; L, 31.06; mol), stir 2.5; h and filter to give a white solid. Wash the recovered solid twice with ethyl acetate (500; mL) and then add it portion wise to a cooled aqueous solution of 2; M sodium hydroxide (3.80; L, 7.60; mol) in an ice bath. Stir the mixture for 1; h, sonicate for 15; min., filter and wash the recovered solid twice with water (200; mL). Dry the solid overnight under vacuum, slurry in dichloromethane (1; L) and filter. Concentrate the filtrate and purify by silica gel chromatography eluting with dichloromethane to give the title compound as a yellow solid (149.77; g, 70%). MS (m/z): 211, 213; (M+1).

Provenance & Evidence