3-oxazine-2,4-diones (1) and (2) with hydrazine hydrate at room temperature gave the 6-hydroxy-5,6-dihydrouracils (7a) and (8a). The structures of the products were determined by 15N n.m.r. analysis. The mechanism of the ring transformation of 1,3-oxazines into pyrimidines and pyrazoles is discussed.
6-甲基-1,3-恶嗪-2,4-二酮(1)和(2)与
水合
肼在室温下反应,得到6-羟基-5,6-二氢尿
嘧啶(7a)和(8a)。产物的结构通过15 N nmr分析确定。讨论了1,3-恶嗪环转化为
嘧啶和
吡唑的机理。