6-Bromo-1H-indazole-3-carbaldehyde is prepared by the reaction of 6-Bromoindole and acetone. The specific synthesis steps are as follows:
To 70g is added in an aqueous solution of sodium nitrite of 20g 6-bromoindole acetone: water (200 ml: 200 ml) solution; room temperature, in to the system by adding 2N HCl solution to pH to 2.5 the left and right; 20 min the rear, with a red brown gas desorbing, slabs system has; 10 min later, TLC detection material disappears, cessation of the reaction, adding to system 1.0L ethyl acetate (EA), two-phase separation, the organic phase with saturated sodium bicarbonate (500 ml * 2) washing, drying organic anhydrous magnesium sulfate, concentrated to obtain 22g compound 2, as a black solid.
