Boron trifluoride etherate → HCID 69425076, compound

To a solution of 3-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-7-methyl-1H-indole-4-carboxylic acid methylamide (100 mg, 0.289 mmol) and ethyl butyrylacetate (92 mL, 0.578 mmol) in CH2Cl2 (2 mL) was added BF3.OEt2 (0.11 mL, 0.867 mmol) dropwise at room temperature. After stirring overnight, the solution was diluted with CH2Cl2 (10 mL) and then washed with saturated aqueous NaHCO3 (10 mL) and brine (10 mL). The organic phase was dried (Na2SO4) and concentrated. The residue was purified by flash chromatography (silica, 50% EtOAc in hexanes) to give 88 mg (82%) of title compound as a yellow solid. 1H NMR (CDCl3): 300 MHz δ 9.54 (bs, 1H), 7.12 (d, J=7.38 Hz, 1H), 6.89 (d, J=7.38 Hz, 1H), 6.05 (d, J=4.71 Hz, 1H), 4.15 (m, 2H), 3.96 (m, 1H), 3.86 (m, 1H), 3.03–2.83 (m, 7H), 2.48 (s, 3H), 2.00 (m, 2H), 1.37 (m, 1H), 1.25 (t, J=6.84 Hz, 3H), 1.22 (m, 1H), 0.87 (t, J=7.17 Hz, 3H).