Chapter 6.3 (2007): Triazines, Tetrazines and Fused Ring Polyaza Systems

This chapter presents the synthesis and reaction of triazines, tetrazines, and fused ring polyaza system. The theoretical studies of complexes of benzene with 1,2,3- triazine, 1,2,4-triazine, 1,3,5-triazine and 1,2,4,5-tetrazine are described in the chapter. New nematodocides, tetrahydrobenzotriazines are synthesized by the BuLi induced cyclization of triazene followed by reaction with an electrophile. One-pot reactions of 1,2-diketones, acid hydrazides, and ammonium acetate in the Bronsted acidic ionic liquid, 1-butylimidazolium tetrafluoroborate, yields 3,5,6-trisubstituted-1,2,4-triazines. Co-ordination of [Ru-(C6H6)Cl2]2 with the product of the condensation of benzildihydrazone with 2-formylpyridine and 2-acetylpyridine is found to promote the formation of 5,6-diphenyl-3-(pyridin-2-yl)-1,2,4-triazine as its cationic Ru-complex. Chiral (up to 91% ee) 4-(1-arylpropyl)amino-3-mercapto-6-methyl-4H-1,2,4-triazin-5-ones are obtained in high yields by enantioselective diethylzinc addition to the exocyclic C=N bond of 4-arylideneamino-3-mercapto-6-methyl-4H-1,2,4-triazin-5-ones using chiral ligands or polymers.