Hydrochloric Acid → 2H-1,4-Benzoxazine

Participants

Reaction Steps

Powdered sodium cyanoborohydride (25 g) is added, in small portions, to a well-stirred and cooled (5°) solution of 1,2,7,8,9,10-hexahydropyrido[3', 4': 4,5]pyrrolo[1,2,3-de][1,4]benzoxazine (20 g) in trifluoroacetic acid (250 ml) at such a rate that excessive frothing is avoided. After the addition is complete, the mixture is stirred at room temperature for 2 hours, treated with 6N hydrochloric acid (150 ml), and refluxed for 30 minutes. It is then cooled and basified with 25% sodium hydroxide and extracted thrice with chloroform. The combined chloroform extracts are washed thoroughly with water, dried over magnesium sulfate, and stripped of the solvent under reduced pressure to furnish a crystalline solid which is recrystallized from hexane to yield the title compound, m.p. 112°-113°.

Provenance & Evidence