845751-59-9

The general procedure for the synthesis of 7-bromo-2H-indazole from the compound (CAS: 845751-60-2) was as follows: (2-bromo-6-methylphenylazo)-tert-butyl sulfide (2b; 880 mg, 3.06 mmol) was dissolved in 10 mL of anhydrous DMSO, and the solution was subsequently added slowly and dropwise to a solution containing potassium tert-butoxide (3.44 g, 30.6 mmol ) in anhydrous DMSO solution and the reaction was carried out under argon protection. The reaction mixture was stirred for 2 h at room temperature and then poured into a mixed solution consisting of 150 g of ice and 150 mL of 2N HCl. The mixture was extracted using ether (2 x 150 mL). The ether extracts were combined, washed with saturated saline and dried with anhydrous magnesium sulfate. Finally, the solvent was removed by evaporation to give 581 mg (96% yield) of the target product 7-bromo-2H-indazole as a beige solid.

[1] Patent: US2004/110815, 2004, A1. Location in patent: Page/Page column 19
[2] Patent: WO2005/16892, 2005, A1. Location in patent: Page/Page column 69
[3] Journal of Medicinal Chemistry, 2012, vol. 55, # 21, p. 9089 - 9106,18