An efficient synthesis of 1-arylideneamino-substituted hexahydro-1H-cyclopenta[d]pyrimidin-2-ones and octahydroquinazolin-2-ones has been developed. The synthesis involves a stereo- and regioselective cascade reaction of the corresponding 4-(tosylmethyl)semicarbazones with 1-morpholinocyclopentene or 1-morpholinocyclohexene to give predominantly bicyclic pyrimidines with an exocyclic CC double bond (80–97%). The later undergo rapid isomerization when heated in THF in the presence of TsOH to form bicyclic pyrimidines with a significant predominance of those with an endocyclic CC double bond (90–97%).

中文翻译：

---

烯胺与半氨基甲酰胺基烷基化试剂的反应：环化的1-氨基嘧啶-2-酮衍生物的直接合成

已经开发出有效合成1-芳基氨基取代的六氢-1 H-环戊[ d ]嘧啶-2-酮和八氢喹唑啉-2-酮的方法。合成涉及相应的4-（甲苯磺酰基甲基）半咔唑酮与1-吗啉代环戊烯或1-吗啉代环己烯的立体和区域选择性级联反应，主要产生带有环外C C双键的双环嘧啶（80-97％）。当在TsOH存在下在THF中加热时，后者会经历快速异构化反应，从而形成双环嘧啶，其显着优势是具有内环C C双键的双环嘧啶（90-97％）。