4.6- dimethyl-1,2,3-triazine

J. W. Streef of. H. J. den Hertog, Abstr. A, XIXth Intern. Congr. Pure Appl. Chem., p. 279 (1963). H. C. van der Plas and B. Haase [ibid., p. 279 (1963)] describe an analogous conversion of 4-chloro-2-methylp5rrimidine into 2,4-dimethyl- -triazine. 

Chloro-4,6-diphenyl- and 2-chloro-4,6-dimethyl- -triazines (318) undergo facile nucleophilic displacements with ammonia, amines, and hydrazine, with alkoxide, or with hydrosulfide ions, A convenient synthesis of monoamino-s-triazines in high yield is the reaction of 2-phenoxy-s-triazine (319) with ammonia or aliphatic amines (30-70°) or with aniline (120°). Triphenoxy- -triazine (320) reacts with all classes of amines without side-reactions... 

Triazine-5,6-dicarboxylic acid, 3-cyano-dimethyl ester... 

The 3-amino-8-oxo derivative of 1,2,4,5,7-pentaazanaphthalene (475) is known as well as various 3-substituted derivatives of the 6,8-dioxo compound. The 3-methylthio- and 3-ethylthio-6,8-dioxo derivatives and their 7-methyl and 5,7-dimethyl analogs were prepared by ring-closure. 3-Ethylthiopyrimido[4,5-e]-as-triazine-6,8-dione was 3-substituted with alkali 2N, 100°, > 30 min) or acid 2N, 100°, < 2 hr, 70% yield) and with ammonia, aniline, piperidine, or monoalkylamines (in pyridine, 115°, 4 hr, 75-85% yield). ... 

The halogenation of 3-methoxy- or 3-methyl(dimethyl)amino-1,2,4-triazine 2-oxides 18 was found to proceed in a similar manner, resulting in 6-halo-1,2,4-triazine 2-oxides 19 (77JOC3498, 78JOC2514). 

The reaction of the fervenulin 1-oxides 100 with secondary amines results in contraction of the 1,2,4-triazine ring to form 2-amino-5,7-dimethylimidazo[4,5-e] pyrimidine-4,6(5/7,7//)-diones 101. The reaction of the same fervenulin 1-oxides 100 with ammonia leads to the 1,2,4-triazine ring cleavage product, 1,3-dimethyl-5-imino-6-isonitrosouracil 102 (94KGS1253). 

The reaction of hydroxyamidrazone 134 with dimethylglyoxal in methanol leads to 5,6-dimethyl-3-phenyl-1,2,4-triazine 4-oxide 135 (71LA12). 

Heteroannelated 1,2,4-triazine 4-oxides—fervenulin 4-oxides 12—were obtained starting from 6-hydrazino-l,3-dimethyl-5-nitrosouracil. Orthocarboxylates, formic acid, dimethyl sulfate, or DMF in the presence of POCI3 were used as cyclization agents (77H273, 78JOC175, 78JOC469). 

The reaction of oxepin and 2,7-dimethyloxepin with dimethyl 3-cyano-l,2,4-triazine-5,6-dicarb-oxylate takes the same course as the cycloaddition to the tetrazine. Two different addition products 11a and 12 are obtained in the case of oxepin, whereas dimethyloxepin yields only the [4 + 2] adduct lib.235... 

A special method, with only two examples, starts from 1,2,4-triazines.20 21 Diels-Alder reaction with the strained dienophile dimethyl tricyclo[4.2.2.02,5]deca-3,7,9-triene-7,8-dicarboxylate (14) is followed by an elimination of nitrogen via a retro-Diels-Alder process. The formed product, however, cannot be isolated, but reacts via another retro-Diels-Alder reaction and an electro-cyclic reaction to provide the azocine derivative 15. The sequence order of the reactions is not clear, but both pathways lead to the same product. 

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). 

The reaction of dimethyl-1,2,4,5-tetrazine-3,6-dicarboxylate 353 with aromatic amines gave (82CB683) pyrazolo[3,4-e][l,2,4]triazines 354 (Scheme 75). 

Formation constants of Ag(I) complexes with 5,7-dimethyl-4a,7a-diphenyloctahydroimidazo[4,5-e][triazin-6-one-3-thione was determined potentiometrically (79MI2). 

Examples of this ring system were synthesized by nucleophillic addition of 613 to dimethyl acetylenedicarboxylate in moist solvents to afford the ylidene-substituted oxazolo[3,2-rf][l,2,4]triazine 614. Its X-ray crystal structure has been described [90JCR(S)354] (Scheme 126). 

Thiazolotriazines 636 (R = CO,Me) were prepared [84JCS(P1)2707] by cycloaddition of dimethyl acetylenedicarboxylate with triazine derivative 632. Derivatives of thiazolo[3,2-b][l,2,4]triazin-3,7-diones 637 have been formed (74JPR163) on reaction with aromatic aldehydes and diazonium salts to give 636 (R = Ar) and 638, respectively. Regioselective catalyzed... 

The benzo analogue 684 of [1,2,4]triazino[3,2-6]thiazoles was prepared (88LA1089) by heating triazine derivative 632 with 2,4-dinitrochloroben-zene or picryl chloride in N,N-dimethyl formamide (Scheme 143). 

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