Synthesis and hydroxylation of 1-alkyl- and 7-alkyl- 1,3,7-triazapyrenium salts

The regioselectivity of quaternization of 1,3,5-triazapyrenes by alkyl halides has been studied. Oxidative hydroxylation of 1-alkyl- and 7-alkyl-1,3,7-triazapyrenium salts gives 1-alkyl-1,2-dihydro-1,3,7-triazapyren-2-ones or 7-alkyl-6,7-dihydro-1,3,7-triazapyren-6-ones respectively. In the absence of an oxidant the hydroxylation of the 1-alkyl-1,3,7-triazapyrenium salts leads to a hydrolytic cleavage of the heterocycle.