The condensation of 5-amino-1, 3-dimethylbarbituric acid (I) with aromatic aldehydes gave 5-benzylideneamino-1, 3-dimethylbarbituric acids (II). Treatment of (II) with thionyl chloride afforded 2-aryl-5, 7-dimethyloxazolo [5, 4-d] pyrimidine-4, 6 (5H, 7H)-diones (IV) in good yields. The reaction of (IV) with phosphorus pentasulfide in pyridine provided 2-aryl-5, 7-dimethylthiazolo [5, 4-d] pyrimidine-4 (5H)-one-6 (7H)-thiones (VI), which were then converted to 2-aryl-5, 7-dimethylthiazolo [5, 4-d] pyrimidine-4, 6 (5H, 7H)-diones (VII) by the action of 30% hydrogen peroxide in acetic acid or thionyl chloride.
5-
氨基-1,3-二甲基
巴比妥酸(I)与芳香醛缩合后得到 5-亚苄基
氨基-1,3-二甲基
巴比妥酸(II)。用亚
硫酰氯处理 (II),可得到 2-芳基-5,7-二甲基
噁唑并[5,4-d]
嘧啶-4,6 (5H,7H)-二酮 (IV),收率很高。(IV)与五
硫化二
磷在
吡啶中反应生成 2-芳基-5,7-二甲基
噻唑并[5,4-d]
嘧啶-4 (5H)-酮-6 (7H)-
硫酮(VI),然后在 30%
过氧化氢在
乙酸或亚
硫酰氯中的作用下转化为 2-芳基-5,7-二甲基
噻唑并[5,4-d]
嘧啶-4,6 (5H, 7H)-二酮(VII)。