Cycloaddition reaction of 8-diazotheophylline with some dipolarophiles:Facile synthesis of new derivatives of 1,2,4-triazino[3,4-f]purine

摘要

[4+2] Cycloaddition of 8-diazotheophylline 2 with dipolarophiles 3-9 affords the corresponding new 1,2,4-triazino[3,4-f]theophyllines 10-16 by refluxing in chloroform.The cycloaddition of 8-diazotheophylline 2 with acrylonitrile 4 in dry benzene was reported recently from our laboratory and it was shown that such a reaction yielded the unexpected 8-phenyltheophylline 1 via free radical mechanism.In order to shed more light on such a reaction,we investigated the reaction of 8-diazotheophylline 2 with electron deficient olefins such as N-aryl maleimide 3,acrylonitrile 4,acryamide 5,ethyl a-cyanocinnamate 6,benzyllidene malononitrile 7,trichloroethylene 8 and azlactone 9.