Reaction Steps
Into a 25 ml round bottom flask equipped with a stir bar, condenser, thermocouple and 3-way valve was charged 3-cyclopentyl-3-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazol-1-yl]propanenitrile (23, 0.697 g, 2.21 mmol, 1.3 equiv), 4-chloro-7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidine (3a, 0.506 g, 1.69 mmol), 1,4-dioxane (4.44 mL), water (4.44 mL), and sodium bicarbonate (NaHCO3, 0.666 g, 7.93 mmol, 4.7 equiv) at room temperature. The resulting mixture was degassed four times backfilling with nitrogen each time before tetrakis(triphenylphosphine)palladium(0) (91.6 mg, 0.079 mmol, 0.047 equiv) was added. The resulting reaction mixture was degassed four times backfilling with nitrogen each time. The reaction was then warmed to 90° C. for 2-6 h. When TLC and HPLC showed that the coupling reaction was deemed complete, the reaction mixture was allowed to cool to room temperature followed by dilution with water (5 mL) and ethyl acetate (10 mL). The two layers were separated, and the aqueous layer was back extracted with ethyl acetate (10 mL). The combined organic fractions were washed with water (10 mL) and saturated aqueous NaCl solution (10 mL), dried over magnesium sulfate (MgSO4), and concentrated under reduced pressure to give the crude product (9) as an amber oil. The crude product was purified by flash column chromatography (SiO2, 0% to 40% ethyl acetate/hexane gradient elution) to afford racemic 3-cyclopentyl-3-{4-[7-(2-trimethylsilanylethoxymethyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl]pyrazol-1-yl}propionitrile (9, racemic SEM-protected compound, 617 mg, 737.9 mg theoretical, 83.6% yield) as a yellow oil. For 9: 1H NMR (DMSO-d6, 400 MHz) δ ppm 8.83 (s, 1H), 8.75 (s, 1H), 8.39 (s, 1H), 7.77 (d, 1H, J=3.7 Hz), 7.09 (d, 1H, J=3.7 Hz), 5.63 (s, 2H), 4.53 (td, 1H, J=19.4, 4.0 Hz), 3.51 (t, 2H, J=8.1 Hz), 3.23 (dq, 2H, J=9.3, 4.3 Hz), 2.41 (m, 1H), 1.79 (m, 1H), 1.66-1.13 (m, 7H), 0.81 (t, 2H, J=8.2 Hz), 0.124 (s, 9H); C23H32N6OSi (MW, 436.63), LCMS (EI) m/e 437 (M++H) and m/e 459 (M++Na).
