To a suspension of 1-benzenesulfonyl-1H-pyrrolo[2,3-b]pyridine (5.0 g, 19.4 mmol) in dry tetrahydrofuran (125 mL) at −78° C. was added freshly prepared lithium diisopropylamide [prepared by adding 1.6 M n-butyllithium in n-hexane (18 mL, 29 mmol) to a 0° C. solution of diisopropylamine (4.4 mL, 31 mmol) in dry tetrahydrofuran (17 mL)] dropwise. The mixture was stirred at −78° C. for 5 min and then treated with (tetrahydro-pyran-4-yl)-acetaldehyde (3.7 g, 29 mmol) dropwise. The resulting mixture was stirred at −78° C. for 1 h and quenched with brine. The mixture was extracted with ethyl acetate (2×150 mL), washed with brine, dried over anhydrous sodium sulfate and concentrated in vacuo. Purification by flash column chromatography (QingDao silica gel, 200-300 mesh, 50% ethyl acetate/hexanes) afforded 1-(1-benzenesulfonyl-1H-pyrrolo[2,3-b]pyridin-2-yl)-2-(tetrahydro-pyran-4-yl)-ethanol as a colorless oil (4.3 g, 57%): LC/MS m/e calcd for C20H22N2O4S [M+H]+ 387.47, observed 387.1.
