Cesium carbonate → 2-(benzyloxy)-5-(2-methoxypyrimidin-4-yl)-6,7-dihydropyrazolo[1,5-a]pyrazin-4(5H)-one

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Reaction Conditions

Reaction Steps

Palladium (II) acetate (2.8 mg, 0.012 mmol) was added to a stirred suspension of 2-(benzyloxy)-6,7-dihydropyrazolo[1,5-a]pyrazin-4(5H)-one (0.1 g, 0.41 mmol), 4-chloro-2-methoxy-pyrimidine (0.120 g, 0.82 mmol), 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl (17.7 mg, 0.037 mmol) and Cs2CO3 (0.19 g, 0.58 mmol) in 1,4-dioxane (2 mL). The mixture was stirred at 100° C. for 24 hours. The solvent was evaporated in vacuo. The crude product was purified by flash column chromatography (silica; 7 M solution of ammonia in MeOH in DCM 0/100 to 95/5). The desired fractions were collected, the solvents evaporated in vacuo and the residue triturated with diethyl ether to yield 2-(benzyloxy)-5-(2-methoxypyrimidin-4-yl)-6,7-dihydropyrazolo[1,5-a]pyrazin-4(5H)-one (51 mg, 35% yield) as a white solid. C18H12N5O3. 1H NMR (500 MHz, CDCl3) δ ppm 4.03 (s, 3H), 4.33 (dd, J=6.6, 5.2 Hz, 2H), 4.64 (dd, J=6.6, 5.2 Hz, 2H), 5.23 (s, 2H), 6.40 (s, 1H), 7.31-7.36 (m, 1H), 7.39 (t, J=7.4 Hz, 2H), 7.42-7.48 (m, 2H), 7.89 (d, J=5.8 Hz, 1H), 8.44 (d, J=5.8 Hz, 1H).

Provenance & Evidence