1,2-Cyclohexanedione → 3-Benzyl-5,6,7,8-tetrahydroquinoxalin-2(1H)-one

Participants

Reaction Conditions

Reaction Steps

A methanol (30 ml) solution of 1,2-cyclohexanedione (13.44 g, 0.12M) was added to phenylalanineamide hydrochloride (20.05 g, 0.1M) dissolved in methanol (200 ml) under cooling below -30° C., and aqueous 12.5N NaOH (20 ml) was added dropwise thereto. The reaction mixture was stirred under -30° C. for 30 mins., whereafter cooling was removed and the mixture was stirred at room temperature for 3 hours. Conc. hydrochloric acid (25 ml) was added to the reaction mixture under ice-cooling, and sodium bicarbonate (15 g) was added after 10 mins. stirring the methanol then being distilled off in vacuo. The residue, to which was added water, was extracted three times with chloroform, and the extract was washed with water, dried with anhydrous magnesium sulfate and concentrated in vacuo. The residue was washed with acetone and recrystallized from acetone to obtain the product (19.7 g, yield: 82.1%).

Provenance & Evidence