Acetic Acid → 7,8-dimethoxy-1-methyl-3,4-dihydro-1H-1,4-benzodiazepine-2,5-dione

Participants

Reaction Conditions

Reaction Steps

Heat under reflux for 6 hours a mixture of 320 mg (1.35 mmol) of 6,7-dimethoxy-1-methyl-1,2-dihydro-4H-3,1-benzoxazine-2,4-dione (XVI), 452 mg (3.24 mmol) of methyl glycinate hydrochloride in 4 ml of pyridine. Add 3 ml of AcOH and heat at 130° C. for 12 hours. Evaporate to dryness. Add 10 ml of a water-ice mixture. Allow to crystallize at 0° C. for 30 minutes. Filter and wash twice with 2 ml of H2O, twice with 1 ml of EtOH and twice with 5 ml of Et2O. Recrystallize in EtOH. One obtains 240 mg of the abovenamed product in the form of colorless crystals. Yield: 71%. M: 260–263° C. 1H-NMR (CDCl3, 300 MHz): d 3.42 (s, 3H, NCH3), 3.75–3.92 (m, 2H, CH2), 3.98 (s, 6H, 2×OCH3), 6.39 (s, 1H exchangeable, NH), 6.69 (s, 1H Ar), 7.37 (s, 1H Ar).

Provenance & Evidence