Formaldehyde → 5-{2-Butoxy-5-[3-(dimethylamino)propanoyl]-3-pyridinyl}-3-ethyl-2-(2-methoxyethyl)-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one

Participants

Reaction Steps

Dimethylamine hydrochloride (280 mg, 31 mmol) was added to formaldehyde (72 mg, 2 mL of a 37-41% aqueous solution) and the mixture sonicated until the white solid dissolved. After 30 min acetic anhydride (1.2 mL) was added and the mixture warmed in a water bath until a clear solution was obtained. A portion of this solution (0.16 mL) was added to 5-(5-acetyl-2-butoxy-3-pyridinyl)-3-ethyl-2-(2-methoxyethyl)-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one (Example 16) (100 mg, 0.24 mmol) and the resulting solution heated in a water bath. After 1 h the reaction was cooled and extracted from saturated sodium bicarbonate solution with ethyl acetate. The organics were washed with a further portion of sodium bicarbonate solution then brine, dried (MgSO4) and concentrated. The residue was purified by flash column chromatography (gradient elution from 100% dichloromethane to 10% methanol:dichloromethane) to give 50 mg product.

Provenance & Evidence