electron-deficient and electron-rich dienophiles to give, via one-step hetero-Diels–Alder cycloaddition reactions, the corresponding 5H-coumarin[4,3-c]pyridin-5-ones. When excess of the dienophile was used, fused azatetracyclo derivatives were also formed via a tandem Diels–Alder and 1,3-dipolar cycloaddition reaction of the dienophile to an azomethine ylide formed by the intermediate 2,3-dihydro-5H-coumarin[4
O-甲基-4-
香豆素甲醛肟作为氮杂二烯与缺电子和富电子的亲二烯体反应,通过一步杂Diels-Alder环加成反应生成相应的5 H-
香豆素[4,3- c ]
吡啶-5-ones。当使用过量的亲双烯体时,通过亲双烯体的串联Diels-Alder和1,3-偶极环加成反应生成由中间体2,3-dihydro-5 H-
香豆素形成的偶氮甲meth内酯,也会形成稠合的氮杂四环衍
生物。4,3 - c ]
吡啶-5-一。新化合物的区域选择性和立体选择性与光谱学(2D NMR)和理论数据非常吻合。提供了一种可能的机制方案。