Sodium hydride → (4-Fluoro-3-trifluoromethyl-benzyl)-(3-methyl-benzo[b]thiophen-2-yl)-carbamic acid tert-butyl ester

To a solution of compound 6-B (2.0 g, 7.59 mmol) in DMF (20 mL), cooled to 0° C., was added 60% NaH (0.334 g, 8.35 mmol) and the reaction mixture was stirred for 15 minutes. 4-Fluoro-3-trifluoromethyl benzyl bromide (1.26 mL, 8.35 mmol) was added drop-wise at 0° C. and the reaction mixture was stirred for 1 hour. The reaction mixture was poured into ice water, extracted with ethyl acetate, the organic phase washed with H2O, brine, dried over MgSO4, filtered, and the solvent evaporated under reduced pressure. The crude oil was purified by flash column chromatography (SiO2) eluting with a 0% EtOAc-heptane to 25% EtOAc-heptane gradient to afford compound 6-C as a clear oil. Compound 6-C was used without further purification in the next step.