Water → 5-(5-fluoro-pyridin-2-yl)-2-(4-hydroxy-phenoxymethyl)-6,7-dihydro-5H-pyrazolo[1,5-a]pyrazin-4-one

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Reaction Steps

A 1M solution of TBAF in THF (0.14 mL, 0.144 mmol) was added to a stirred solution of 2-[4-(tert-butyl-dimethyl-silanyloxy)-phenoxymethyl]-5-(5-fluoro-pyridin-2-yl)-6,7-dihydro-5H-pyrazolo[1,5-a]pyrazin-4-one (45 mg, 0.096 mmol) in THF (0.5 mL). The mixture was stirred at room temperature for 16 hours. The mixture was treated with water and extracted with AcOEt. The organic layer was separated, dried (MgSO4), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; 7 N solution of ammonia in MeOH in DCM 0/100 to 10/90). The desired fractions were collected and the solvents evaporated in vacuo to yield 5-(5-fluoro-pyridin-2-yl)-2-(4-hydroxy-phenoxymethyl)-6,7-dihydro-5H-pyrazolo[1,5-a]pyrazin-4-one as a white solid. 1H NMR (500 MHz, DMSO-d6) δ ppm 4.40-4.48 (m, 2H), 4.48-4.55 (m, 2H), 4.99 (s, 2H), 6.65-6.72 (m, 2H), 6.83-6.88 (m, 2H), 6.95 (s, 1H), 7.85 (td, J=8.7, 3.2 Hz, 1H), 7.93 (dd, J=9.1, 4.2 Hz, 1H), 8.50 (d, J=3.2 Hz, 1H), 8.96 (s, 1H).

Provenance & Evidence