To a suspension of 1-benzenesulfonyl-5-methoxymethyl-1H-pyrrolo[2,3-b]pyridine (1.54 g, 5.1 mmol) in dry tetrahydrofuran (40 mL) at −78° C. was added n-butyllithium in n-hexane (1.6 M, 6.63 mmol, 4.14 mL) dropwise. The mixture was stirred at −78° C. for 5 min and then treated with cyclopentanecarbaldehyde (9.2 mmol, 1.03 g) dropwise. The resulting mixture was stirred at −78° C. for 1 h and quenched with brine. The mixture was extracted with ethyl acetate (2×200 mL), washed with brine, dried over anhydrous sodium sulfate and concentrated in vacuo. Purification by flash silica gel chromatography (silica gel from QingDao, 200-300 mesh, glass column from Shanghai SD company, 25% ethyl acetate/hexanes) afforded 1-(1-benzenesulfonyl-5-methoxymethyl-1H-pyrrolo[2,3-b]pyridin-2-yl]-2-cyclopentyl-ethanol as a light yellow solid (710 mg, 33.6%): LC/MS m/e calcd for C22H26N2O4S [M+H]+ 415.53, observed 415.0.
