Inverse electron-demand in Diels-Alder reaction

In addition to 1,2,4-triazines condensed with carbocycles, 1,2,4-triazines condensed with heterocycles can also be used as dienes with inverse electron demand in Diels-Alder reactions. Thus, it has been shown that pyrimido[4,5-e]-1,2,4-triazines react with enamines to yield pyrido[2,3-tflpyrimidines 29 (5-deazapteridines).415... 

Since cycloadditions of tetrazines follow the inverse electron demand in Diels-Alder reactions, cycloadditions to electron-rich enamines usually proceed easily and under mild conditions. In general, elimination of amine takes place from the initially formed dihydropyridazine to give the fully conjugated pyridazines as products. 

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See also in sourсe #XX -- [ , , , ]

See also in sourсe #XX -- [ , , , ]

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