Methanol → (4-Morpholin-4-yl-phenyl)-acetic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

A mixture of 4-morpholinoacetophenone (4.61 g, 22 mmol), sulfur (2.16 g, 67 mmol), and morpholine (6 mL, 67 mmol) was heated at 80° C. for 1 h then heated under reflux for 18 h. The hot reaction mixture was poured into warm ethanol. Upon cooling to 25° C., a precipitate formed. The precipitate was filtered to provide a tan solid (4.16 g). This crude tan solid was then treated with concentrated acetic acid (16 mL), concentrated sulfuric acid (2.4 mL), and water (3.6 mL). The resulting reaction mixture was heated under reflux for 4 h and then poured into water. The water was removed in vacuo to provide crude (4-morpholin-4-yl-phenyl)-acetic acid as a brown oil (8.20 g). This crude (4-morpholin-4-yl-phenyl)-acetic acid was dissolved in methanol (100 mL) and then slowly treated with concentrated sulfuric acid (1 mL). The reaction mixture was heated under reflux for 66 h. The reaction mixture was allowed to cool to 25° C. and then concentrated in vacuo to remove methanol. The residue was diluted with water (200 mL) and then treated with a 10% aqueous sodium hydroxide solution until pH=9. The aqueous phase was extracted with ethyl acetate (3×100 mL). The combined organic extracts were washed with a saturated aqueous sodium chloride solution (1×100 mL), dried over sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 70-230 mesh, 3/1 to 1/1 hexanes/ethyl acetate gradient elution) afforded (4-morpholin-4-yl-phenyl)-acetic acid methyl ester (2.22 g, 42% for 3 steps) as a yellow oil: EI-HRMS m/e calcd for C13H17NO3 (M+) 235.1208, found 235.1214.

Provenance & Evidence