Potassium Carbonate → 7-Methoxy-2H-1,4-benzoxazin-3(4H)-one

Participants

Reaction Steps

A reaction mixture was prepared from 19.6 g of N-chloroacetyl-2-hydroxy-4-methoxyaniline, 13.8 g of potassium carbonate and 500 ml of acetone. The mixture was refluxed with stirring for about 5 hours and was then cooled. Inorganic salts were separated by filtration, and the solvent removed from the filtrate in vacuo. The resulting residue was dissolved in methylenedichloride. The methylenedichloride solution was washed with saturated aqueous sodium chloride and then dried. Fourteen grams of 3,4-dihydro-7-methoxy-2H-[1,4]benzoxazin-3-one were obtained. NMR indicated complete cyclization to the lactam. Recrystallization from ethyl acetate/hexane yielded product melting at 164°-165° C.

Provenance & Evidence