N-bromobutanimide → 4-(4-Bromo-2-fluorophenylamino)-indazole-1,5-dicarboxylic acid di-tert-butyl ester

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Reaction Steps

To a solution of 4-(2-fluoro-4-trimethylsilanyl-phenylamino)-indazole-1,5-dicarboxylic acid di-tert-butyl ester (850 mg, 1.7 mmol) in DCM (10 mL) at −15° C. was added N-bromosuccinimide (303 mg, 1.7 mmol) as a solution in DCM (3 mL) dropwise. The reaction mixture was stirred at −15° C. for 1.25 hours before DCM was added and the solution washed (saturated aqueous NaHCO3 then water), dried (Na2SO4), filtered and concentrated in vacuo. The resultant residue was subjected to flash chromatography (Si—PPC, gradient 0 to 10% ethyl acetate in cyclohexane) to give the title compound as an orange gum (790 mg, 92%). LCMS (method B) RT=5.41 min, [M+CH3CN+Na]+=569/571.

Provenance & Evidence