Pyrido triazine

Thermolysis of 1-imidoyliminopyridinium N-ylides 109 gave the pyrido-triazines 110 in addition to 111 and 112 (76CL413 77JOC443). Compounds 109 were obtained by the reaction of pyridinium salts 107 with 108. 

An unusual reaction involving s-triazine (247) and ethyl acetoacetate with sodium ethoxide leads eventually to the pyrido[4,3-ring opening and Dimroth-type rearrangement of the intermediate (248) (80JHC389>. 

Cyclopenta[e]pyrido[2,l-/][l,2,4]triazines synthesis, 3, 423 Cyclopentaquinolinones synthesis... 

The reaction of the sodium salts of pyrido[2,3-e]-l,2,4-triazin-3(4//)-one 1-oxide 22 (Y = N) or l,2,4-benzotriazin-3(4//)-one 1-oxide 23 with acetobro-moglucose results in tetra-(9-acetyl derivatives of /3-D-glucopyranosides 24, 25 deacetylation of 25 gives nucleosides 26 (82JHC497). 

Treatment of 1,2,4-triazines 91a-91e with the electron-deficient die-nophile dimethyl acetylenedicarboxylate gave products, depending on the substituents [77LA( 10) 1718]. Pyrrolo-[2, -/][ ,2,4]triazines 92 were obtained via [4 + 2]-cycloaddition [77LA(9)1413, 77LA( 10)1718] with 91, but interaction with 91b in the absence of solvent gave, in addition to 92, the pyrido[2,l-/][l,2,4]triazine 93 and [l,3]oxazino[2,3-/][l,2,4]-triazine 94. In case of 91a pyridine and benzene derivatives were also formed in addition to 92 (Scheme 23). 

Lipophilicity and specific hydrophobic surface area were determined by using reversed-phase thin-layer chromatography for fused heterocyclic ring systems including five pyrido[2,iy][l,2,4]triazine derivatives <1998MI64>. 

Pyridyl)-2//-pyrido[l,2- ][l,3,5]triazine-2,4(3//)-dithione 84 js the dimeric form of pyridylisothiocyanate 85. It exists as a brick-red crystalline dimer at ambient temperature, which dissociates to the pale yellow monomer 85 upon heating (Scheme 4) <2004JHC99>. 

An unexpected ring formation involving a ring transformation occurred in the reaction of the pyrido[l,2- ]-[l,2,4]triazine derivative 101 with dimethyl acetylenedicarboxylate, and tricyclic compounds 102 were obtained in high yields (Equation 10) <2001JHC205>. 

In contrast to some analogous structures, pyrido[2,l-f][l,2,4]triazine 108 is quite stable toward atmospheric oxygen. It reacts, however, with singlet oxygen in a cycloaddition reaction, and the intermediate 109 thus formed loses nitrogen resulting in the pyridone 110 (Scheme 8) <2001JHC205>. 

The pyrido[l,2-tf][l,3,5]triazine-2,4(3//)-dione derivative 89 was obtained in a cycloaddition reaction of diphenyl-methyl isocyanate 90 with 2-pyridyl isocyanate 91 derived from the corresponding acyl azide via Curtius rearrangement <2002ARK438>. Compound 89 was also synthesized by the reaction of diphenylacetyl chloride 118 and picolinyl azide 116a in the presence of triethylamine (Scheme 11) <2002ARK438>. ... 

Aminopyridine was also reacted with iV,./V -bis(l-chloroalkylidene)urea derivatives <1995UKZ37> or 1-chloro-alkylisocyanates <1995UKZ63> to prepare pyrido[l,2- ][l,3,5]triazin-4-ones. 

The pyrido[2,l- ][l>2,4]triazines 108 were synthesized from hydrazinopyridine 145 with iminoyl chlorides under mild conditions (Equation 20) <2001JHC205>. 

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