Methanol → 1-[3-Cyclopentyl-2-(4-ethanesulfonyl-phenyl)-propionyl]-3-methyl-urea

Participants

Reaction Conditions

Reaction Steps

3-Cyclopentyl-2-(4-ethanesulfonyl-phenyl)-propionic acid ethyl ester (500 mg, 1.48 mmol) and methyl urea (274 mg, 3.70 mmol) were treated with a solution of magnesium methoxide in methanol (7.4 wt %, 6.5 mL, 4.43 mmol). The reaction mixture was then concentrated in vacuo to approximately one-half the volume of methanol. The resulting reaction mixture was then heated under reflux for 2 d. The reaction mixture was allowed to cool to 25° C. and then diluted with ethyl acetate (25 mL). The mixture was filtered through a pad of celite, and the celite pad was washed with ethyl acetate (50 mL). The resulting filtrate was washed with water (40 mL) then the water layer was further extracted with ethyl acetate (40 mL). The combined organic layers were dried over magnesium sulfate, filtered, and concentrated in vacuo to afford a colorless oil. The oil was treated with a solution of 2/1 hexanes/ethyl acetate (10 mL), and a white solid began to precipitate. The suspension was placed in the freezer to enhance crystallization. The solid was filtered to afford 1-[3-cyclopentyl-2-(4-ethanesulfonyl-phenyl)-propionyl]-3-methyl-urea (178 mg, 33%) as a white solid: mp 200-201° C.; FAB-HRMS m/e calcd for C18H26N2O4S (M+H)+367.1691, found 367.1697.

Provenance & Evidence