1 ,2 ,3,4 -Tetrahydro-2 ,4 -dioxo

Much more is known about tetrahydro-l,2,4-tetrazines which can form tautomeric structures with more than one double bond in the ring. These include the tetrahydro-oxo(thioxo)-1,2,4-triazines and tetrahydro-dioxo(thioxo)-l,2,4-triazines, which, in the absence of a principal group of higher priority, are more usually named as dihydro-1,2,4-triazinones and dihydro-1,2,4-tri-azinethiones. Still better known are the tetrahydro-dioxo-l,2,4-triazines and their mono- and di-thiooxo analogues, because the 3,5-isomers [l,2,4-triazine-3,5(2//,4//)-diones, 1,2,4-triazine-3,5(2/7,4//)-dithiones, and dihydro-3/5-thioxo-l,2,4-triazin-5/3-ones] are aza-uracil derivatives. 

The diesters may react with hydrazine in acidic medium to give 4.7-dioxo-4.5,6.7-tetrahydro[4.5,d]azolopyridazine (Scheme 28) (107). The... 

H-Cyclopenta[7,8]naphtho[2,3-6]furan-7-yl glyoxylate, 2,3,6,10-tetrahydro-6-hydroxy-6-methyl-3,10-dioxo-, methyl ester H NMR. 4, 560 (66JCS(C)743) Cyclopenta[6]quinoline, 6,7,8,9-tetrahydro- C NMR, 2, 122 (77JOC300, 77JOC2742)... 

Glutamic acid, p-aminobenzoyl-2-amino-8-methyl-4,9-dioxo-6,7,8,9-tetrahydro-4H-pyrazino[l,2-u][l,3,5]tria2in-7-ylmethyl ester, 3, 308... 

Indole, 4,5,6,7-tetrahydro-4,7-dioxo-structure, 4, 303 Indole, tetrahydro-3-methyl-synthesis, 4, 109 Indole, 2-(2-thienyl)-nitration, 4, 211 Indole, 3-thio-synthesis, 4, 368 Indole, 2-thioalkyl-synthesis, 4, 152 Indole, 3-thiocyano-synthesis, 4, 368 Indole, 1-tosyloxy-rearrangement, 4, 302 Indole, 1,2,3-trialkyl-Mannich reactions, 4, 228 Indole, 3-(tricyanovinyl)-nucleophilic addition reactions, 4, 281 reactions... 

Purine, 2-amino-6,8-dioxo-I,6,7,8-tetrahydro-reactions, 5, 557 Purine, 6-amino-2-fluoro-synthesis, S, 597 Purine, 2-amino-9-methyI-sulfonylation, 5, 551 Purine, 6-amino-2-methyIthio-hydrolysis, 5, 560... 

Purine, 6,8-dioxo-1,6,7,8-tetrahydro-methylation, 5, 534 synthesis, 5, 596 thiation, 5, 557... 

Pyridazine, 4-diazo-5,6-dioxo-1 -phenyl-1,4,5,6-tetrahydro-rearrangement, 3, 10 Pyridazine, 4,5-di-S-butyl-perfluoro... 

According to the triazine nomenclature, 5-azauracil is 2,4-dioxo-l,2,3,4-tetrahydro-l,3,5-triazine (2). The subject index of Chemical Abstracts prefers s-triazine-2,4(lH,3H)-dione. Furthermore, some authors use a name derived from the lactim structure, 2,4-dihydroxy-s-triazine (3). The numbering of the substituents is the same for all these types of nomenclature. 

According to systematic triazine nomenclature, 6-azauracil is 3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine (42). The indexes of the Chemical Abstracts describe it as as-triazine-3,5(2H,4H)-dione. In addition ... 

In this connection the possibility of oxidation of these substances to the tetrahydro derivatives should be mentioned. It was made use of by Thiele and Bailey for the preparation of 6-methyl-3,5-dioxo-2,3,4,5-tetrahydro-l,2,4-triazine (6-azathymine) (46) and only recently by Grundman et al. for that of 6-azauracil (42). 

It was observed already by BougaulU that the reaction of 6-benzyl-3,5-dioxo-2,3,4,5-tetrahydro-l,2,4-triazines with alkyl halides in an alkaline solution yields a mixture of the 4-mono- and 2,4-dialkyl derivatives. This mixture of alkylation products can be readily sepa-... 

By comparing the dissociation constant of 6-azauracil and 6-aza-uridine with those or uracil and uridine, 6-azauridine is now considered to be 1-ribofuranosyl derivative (2-ribofuranosyl-3,5-dioxo-2,3,4,5-tetrahydro-l,2,4-triazine), The same was shown more exactly by comparing the UV and IR spectra and the dissociation constants of 6-azauridine with the two monomethyl derivatives of 6-aza-uracil," Enzymatic synthesis thus, proceeds, in the same way in natural bases and in their aza analogs. 

Alkyl and 6-aryl derivatives of 3,5-dioxo-2,3,4,5-tetrahydro-l,2,4-triazine or of its thio analogs have been mentioned before in this review (e.g., Section II,B,2,a). Some of theih contained functional... 

Other oxo-j8-carbolines which have been converted into 1,2,3,4-tetrahydro-j8-carbolines are 2-benzyl-1,2,3,4-tetrahydro-1,3-dioxo-j8-carboline (85 R = CH2C6H5), which was reduced to 2-benzyl-1,2,3,4-... 

Benzyl-l,3-dioxo-l,2,3,4-tetrahydro-j8-carboline (189) was prepared by heating the benzylamide 188 with polyphosphoric acid on a... 

By reacting phosphorous pentasulfide with dioxo derivatives of tetrahydro-l,3-oxazine, the oxygen atoms of both carbonyl groups are replaced by sulfur (27) ... 

Oxo-2,3,6,7-tetrahydro-5//-pyrido[l,2,3- /e]-l,4-benzoxazine-2-carbox-ylates (291, X = H2) were obtained by hydrogenation of 4-substituted 3, 4-dihydro-2//-1,4-benzoxazine-2-carboxylates (290, X = H2) over 10% Pd/C catalyst, then by the treatment of free acids with (CF3C0)20 (99EUP894796). 5,7-Dioxo-2,3,6,7-tetrahydro derivatives 291 (X = 0) were prepared similarly from 290 (X = O). The products 291 (X = O) exist in 7-hydroxy-5-oxo-2,3-dihydro-5// tautomeric form. 

Naphthoquinone reacts in 30 minutes to give l,2,3,4-tetrahydro-l,4-dioxo-naphthalene in 70% yield. After recrystallization from hexane, the product has mp 95-97° 10). 

Chemical Name Sodium salt of (6R,7R)-7-[2-(2-amino-4-thiazolyl)-2-(methoxyimino)ace-tamido] -8-oxo-3-[[(1,4,5,6-tetrahydro-4-methyl-5,6-dioxo-as-triazin-3-yl)thio] methyl] -5-thia-1 -azabicycio [4.2.0] oct-2-ane-2-carboxylic acid... 

Dioxo-l,3-dimethyl-tetrahydro-imidazol- (4-spiro-2) - 4,6,7-trimethyl-1,2,3.4-tetrahydro-chinoxalin ... 

Bei Verwendung eines groBen Oberschusses von Lithiumalanat wird 2,4-Dioxo-3,3- dibutyl-3,4,7,8- tetrahydro-2H,6H- (pyrimido-[2,l-b]-l,3-oxazin) mit einem diacylierten Isoharnstoff-Gertist in 5,5-Bis-[hydroxymethyl]-nonan (66% d.Th.) und 2-Oxo-hexahy-... 

Dioxo-2,3-dimethyl-1,2,3,4-tetrahydro-phthalazin wird in Acetat-Puffer im we-sentlichen zuml-Oxo-2,3-dimethyl-l,2,3,4-tetrahydro-phthalazin (80% d.Th.) reduziert, in 4n Salzsaure wird dagegen unter Methylamin-Abspaltung 1 -Oxo-2-methyl-2,3-dihy-dro-isoindol (46% d.Th.) erhalten1 (vgl. a. S. 595f.) ... 

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