A first synthesis of 3,9-dihydro-9-aryl-2H-[1,2,4]-oxadiazolo[3,2-b]quinazolin-2-ones is described via the thermal cyclisation of ethyl-(4-aryl-3-oxido-2-quinazolinyl)-carbamates followed by borohydride reduction. A more direct route to 3,9-dihydro-2H-[1,2,4]-oxadiazolo[3,2-b]quinazolin-2-ones, involving the reductive-ring closure of ethyl-(3-oxido-2-quinazolinyl)-carbamate, gives access to the parent unsubstituted heterocycle in good yield. This reaction has been extended to a variety of 7- and 9-substituted 3,9-dihydro-2H-[1,2,4]-oxadiazolo[3,2-b]quinazolin-2-ones.
通过乙基-(4-芳基-3-
氧代-2-
喹唑啉基)
氨基甲酸乙酯的热环化和
硼氢化还原,首次合成了 3,9-二
氢-9-芳基-2H-[1,
2,4]-噁二唑并[3,2-b]
喹唑啉-2-
酮。3,9-二
氢-2H-[1,
2,4]-噁二唑并[3,2-b]
喹唑啉-2-
酮的更直接路线涉及乙基-(3-
氧代-2-
喹唑啉基)-
氨基甲酸乙酯的还原环闭合,从而以良好的收率获得母体未取代的杂环。该反应已扩展到多种 7-和 9-取代的 3,9-二
氢-2H-[1,
2,4]-噁二唑并[3,2-b]
喹唑啉-2-
酮。