Bromine → Thiocyanic acid, 2,3-dihydro-6-(trifluoromethyl)-1H-indol-5-yl ester

A mixture of 6-trifluoromethylindoline (D1) (9.7 g, 52 mmol) and potassium thiocyanate (10.09 g, 104 mmol) in methanol (200 ml) was treated with a solution of bromine (2.82 ml, 55 mmol) in methanol (35 ml) dropwise over 0.5 h at −5-0° C. The reaction mixture was allowed to warm to room temperature and stirred overnight then evaporated to dryness. The residue was partitioned between aqueous K2CO3 (100 ml) and dichloromethane (3×100 ml). The combined extracts were dried (Na2SO4) and evaporated and the residue chromatographed, on silica using 2-30% ethyl acetate/petroleum ether as eluant to afford the title compound (9.1 g, 72%) as a yellow solid.