A solution of diisopropylamine (0.43 mL, 3.07 mmol) in tetrahydrofuran (4 mL) was cooled to −78° C. under a nitrogen atmosphere. n-Butyllithium (1.24 mL of a 2.5 M solution in hexanes) was added dropwise and the reaction mixture was stirred for 30 minutes at −78° C. and then warmed to −30° C. A solution of 1-(phenylsulfonyl)-1H-pyrrolo[2,3-c]pyridine (Reference Example 12) (400 mg, 1.55 mmol) and N,N,N′,N′-tetramethylethylenediamine (0.24 mL, 1.59 mmol) in tetrahydrofuran (4 mL) was added and the reaction mixture was stirred for 45 minutes. A solution of 3-furfural (0.27 mL, 3.12 mmol) in tetrahydrofuran (3 mL) was added dropwise. The reaction mixture was allowed to warm to ambient temperature over 2 h. Saturated ammonium chloride solution (5 mL) was added to quench the reaction mixture. The reaction mixture was diluted with water (10 mL) and extracted with ethyl acetate (3×25 mL). The combined organic extracts were washed successively with water and brine, dried over sodium sulfate and concentrated to dryness. Recrystallization from methanol gave 3-furyl[1-(phenylsulfonyl)-1H-pyrrolo[2,3-c]pyridin-2-yl]methanol (208 mg, 38%) as an off-white solid: mp 168-171° C.; 1H NMR (500 MHz, DMSO-d6) δ 6.24 (1H, d, J=5.8 Hz), 6.40 (1H, d, J=5.8 Hz), 6.48 (1H, d, J=1.1 Hz), 6.84 (1H, s), 7.55-7.62 (5H, m), 7.68-7.71 (1H, m), 7.92-7.94 (2H, m), 8.35 (1H, d, J=5.2 Hz), 9.23 (1H, s); ESI MS m/z 355 [C18H14N2O4S+H]+; HPLC (Method A) >99% (AUC), tR=15.4 min.
