Spirobarbituric acids

The structure of this compound is confirmed by the preparation of the 1-acetyl derivative, acid degradation to 4-methylquinoxalin-3-one-2-carboxylic acid (12), and alternative synthesis from the acid chloride of (12) and AW -dimethyluread A most unusual cyclization occurs when AW-dimethyl-o-phenylenediamine (15) is treated with alloxan in ethanolic solution this apparently involves an A-methyl group and leads to the formation of the spirobarbituric acid (16). The struc-... 

Spirobarbituric acids. A mixture of spirotetrahydropyran-4,5-barbituric acid, -phosphoric acid, and KI vigorously shaken at 135° for 10 hrs. 5,5-bis-... 

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