General procedure for the synthesis of 2-chloro-7-cyclopentyl-7H-pyrrolo[2,3-D]pyrimidine-6-methanol from 3-(2-chloro-4-(cyclopentylamino)pyrimidin-5-yl)prop-2-yn-1-ol: Compound (3) (5 g, 19.9 mmol) was dissolved in THF (50 mL) under the protection of nitrogen and stirred at 29 °C. To this solution was slowly added 1.0 M tetrabutylammonium fluoride in THF solution (45 mL) and subsequently the reaction mixture was heated to 60 °C and the progress of the reaction was monitored by TLC. Upon completion of the reaction, the mixture was concentrated under reduced pressure and the residue was dissolved in 2-propanol (10 mL) and stirred at 50 °C until complete dissolution. The resulting clarified solution was cooled to 29 °C, water (75 mL) was added slowly and stirring was continued for 4 hours. The precipitated solid was collected by filtration, washed with water and dried under vacuum at 50 °C to give compound (4) as a brown solid in 68% yield, melting point 173-175 °C. 1H NMR (400 MHz, DMSO-d6) δ: 1.64-1.65 (m, 2H, -CH2), 1.98-2.03 (m, 4H, -CH2), 2.22- 2.29 (m, 2H, -CH2), 4.67 (d, 2H, J=5.12Hz, -CH2OH), 4.87-4.89 (m, 1H, -NH-CH-), 5.52 (s, 1H, -CH2OH), 6.55 (s, 1H, Ar-H), 8.82 (s, 1H, Ar-H).13C NMR (75.46 MHz, DMSO-d6) δ: 152.3, 151.5, 150.9, 144.7, 118.21, 98.5, 56.4, 52.3, 30.7, 24.9. ESI-HRMS (m/z): the calculated value of [M+] for C12H14ClN3O was 251.7129 and the measured value was 251.8001.