Acetic Acid → (S)-3-[1-(4,6-dimethyl-benzo[d]isothiazol-3-ylmethyl)-2,4-dioxo-1,4-dihydro-2H-pyrido[3,2-d]pyrimidin-3-yl]-pentanoic acid

Participants

Reaction Steps

To a solution of 80 mg of (S)-3-[1-(4,6-dimethyl-benzo[d]isothiazol-3-ylmethyl)-2,4-dioxo-1,4-dihydro-2H-pyrido[3,2-d]pyrimidin-3-yl]-pentanoic acid methyl ester in 1,4-dioxane (2.5 mL) is added lithium hydroxide solution (11 mg of lithium hydroxide monohydrate in 0.5 mL of water) at room temperature. The solution is stirred at the same temperature for 3.5 h. Then 0.5 mL of acetic acid is added along with 25 mL of water. The mixture is extracted with ethyl acetate (3×50 mL). The combined organic layers are dried over sodium sulfate and concentrated. The residue is purified by flash chromatography on silica gel to give 26 mg (34%) of (S)-3-[1-(4,6-dimethyl-benzo[d]isothiazol-3-ylmethyl)-2,4-dioxo-1,4-dihydro-2H-pyrido[3,2-d]pyrimidin-3-yl]-pentanoic acid; LCMS (ESMS): m/z 439.12 (M+H+).

Provenance & Evidence