Norbornadiene, reaction with triazines

In a similar way, nucleophilic substitution of hydrogen in 1,2,4-triazine 31 with lithium derivatives of polynuclear arenes (pyrene, phenanthrene, triphenylene), followed by an aza-DA reaction with 2,5-norbornadiene or morphohnocyclopentene gave the novel polyarenes, modified photolumi-nescent 5-phenyl-2,2 -bipyridines 32 (14MC117). 

The presence of electron-withdrawing groups in the 1,2,4-triazine ring facilitates the cycloaddition reaction. Indeed, ethyl 3-(2-pyridinyl)-l,2,4-triazin-6-carboxylates 170 or 6-cyano-1,2,4-triazines 171 and 172 react with 2,5-norbornadiene on reflux in ethanol or benzene (Scheme 94) <200382400, 2003TL693, 2003JOC2882, 2005TL6111>. 

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