Methyl p-toluenesulfonate → (R)-2-Chloro-7-ethyl-8-isopropyl-5-methyl-6-oxo-5,6,7,8-tetrahydropyrimido[4,5-b]pyrazine

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Reaction Steps

The crude compound (7R)-2-chloro-7-ethyl-8-isopropyl-5,7-dihydropteridin-6-one 22c (12.10 g, 47.50 mmol) was dissolved in 180 mL of acetone followed by the addition of methyl p-toluenesulfonate (13.28 g, 71.30 mmol) and potassium carbonate (13.11 g, 95 mmol). The reaction solution was heated to reflux for 3 hours with stirring and filtered. The filtrate was concentrated under reduced pressure, added with 100 mL of water and extracted with dichloromethane (100 mL×3). The combined organic phase was washed with saturated sodium chloride solution (100 mL), then dried over anhydrous magnesium sulfate, filtered and the filtrate was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography to obtain the title compound (7R)-2-chloro-7-ethyl-8-isopropyl-5-methyl-7H-pteridin-6-one 22d (10.80 g, yield: 84.7%) as a white solid.

Provenance & Evidence