Into a 250 mL three-neck round bottom flask equipped with a stir bar, condenser, thermocouple and nitrogen inlet was charged 4-(1H-pyrazol-4-yl)-7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo [2,3-d]pyrimidine (5, 10.3 g, 0.033 mol), 2-butenenitrile (36, 3.0 mL, 0.037 mmol, 1.12 equiv) and acetonitrile (100 mL, 2.0 mol) at room temperature. The resulting mixture was treated with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, 2.0 mL, 0.013 mol, 0.4 equiv) and was subsequently warmed to 55° C. The reaction mixture was stirred at 55° C. for 15-20 h. When LC/MS showed the reaction was deemed complete, the reaction mixture was concentrated under reduced pressure to yield an orange oil. The crude product was then purified by flash column chromatography (SiO2, 40-80% ethyl acetate/hexane gradient elution) to afford 3-[4-(7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]butanenitrile (37, 12.3 g, 12.62 g theoretical, 97.5% yield) as a colorless oil, which solidified upon standing at room temperature in vacuo. For 37: 1H NMR (CDCl3, 400 MHz) δ ppm 8.84 (s, 1H), 8.33 (s, 1H), 8.30 (s, 1H), 7.39 (d, 1H, J=3.8 Hz), 6.79 (d, 1H, J=3.8 Hz), 5.67 (s, 2H), 4.77 (m, 1H), 3.53 (t, 2H, J=8.2 Hz), 3.05 (dd, 1H, J=16.8, 6.2 Hz), 2.98 (dd, 1H, J=16.8, 6.3 Hz), 1.79 (d, 3H, J=6.5 Hz), 0.91 (t, 2H, J=8.3 Hz), −0.068 (s, 9H); C19H26N6OSi (MW, 382.53), LCMS (EI) m/e 383 (M++H).
