1.2.4- Triazine-3,5-dione derived from

The IR spectral data were used successfully to identify l,2,4-triazine-3,6-diones derived from reactions of hydrazines with a-lactams <1998JOC9128>. 

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. 

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>. ... 

The structures of several compounds containing the pyrrolo[l,2,4]triazine moiety have been established by X-ray crystallography, as for example pyrrolo[l,2- ][l,2,4]triazine 13 <1997J(P1)1829>, 4-acetyl-l-phenyl-2a,3,5-triaza-benz[r-,<7]azulene 14 <2000H(53)323>, heterodiquinane 15 <1998CL1135>, cation 16 derived from methylation of 3-phenylcyclohepta[4,5]pyrrolo[l,2- ][l,3,5]triazine-2,4(377)-dione <2005H(65)1629>, 2-phenyl-3-phenyl-... 

A new, simple, synthesis of 2,4-diaryl-l, 3,5-triazines is shown in Scheme 1. It arose from an attempt to obtain the pyrano[4,3-rf]pyrimidine system by reacting aryl amidines with the 3-methoxymethylenedihydropyran-2,4-dione (1 X= CH2). As well as the desired products, diaryl-I,2,3-triazines were obtained in 30-40% yield. The use of 5-methoxymethylene-2,2-dimethyl-l,3-dioxan-4,6-dione (1 X= 0)(derived from Meldrum s acid) gives the triazines in better yield (> 50%). It was also observed that 3-methoxymethylenefuran-2,4-dione reacted with 5-methylisothiouronium bromide to yield 2,4-bismethylthio-l,3,5-triazine [95M99]. 

Interaction of 24 with ethyl chloroacetate in methanolic sodium methox-ide afforded the triazin-3,14-dione derivative 27. The alternate structure 28 was excluded on the basis of spectral data [58,59]. Based on the reaction conditions, (sodium methoxide) structure 27 is thought to result from the initial formation of a sodium salt on the less basic imino nitrogen atom, which cyclizes into 27 with elimination of NaCl and EtOH (Scheme 12). The IR spectrum of 27 showed a characteristic C = 0 absorption band at 1650 cm-1,... 

Aza-l,3-dienes react with diazenedicarboxylates and 4-phenyl-3ff-l,2,4-triazole-3,5(4//)-dione to afford in good yield, l,2,3,6-tetrahydro-l,2,4-triazines 14 and 15, respectively. The relative configuration of the substituents at C-3 and C-6 of one product derived from diethyl diazenedicarboxylate was ascertained by X-ray analysis32. 

Cyclocondensation between l,2-dihydroquinoxalin-2-ones and l,2,4-triazine-3,5-dione derivatives involves the carbonyl group of the 1,2,4-triazinedione and not the carbonyl group of the quinoxalinones <04JHC597>. New examples of the synthesis of pyridine and 2,2 -bipyridine derivatives from a variety of substituted 1,2,4-triazines through Diels-Alder reactions have been described <04T8893>. 

The addition of singlet nitrene derived photochemically from the azido-1,3,5-triazine (130) to nitriles (131) has been reported.77 The adducts (132) are further converted thermally into the triazine-diones (133). 

Dihydropyridines react with s-triazine in the presence of sodium hydride to give l,4-dihydro-l,6-naphthridones in fair to good yields (Table VII, entry 5). Alternative reagents for this reaction are amino-acetals followed by ammonia (Table VII, entry 6). Naphthyridines have also been prepared by the reactions of enaminones derived from cyclohexane-1,3-diones with pentafluorobenzaldehyde in glacial acetic acid (85JHC159). 

Pyrimido[5, 4 4,5]pyrazolo[3,2-c][l,2,4]triazine derivatives 1049and 1050 were prepared by treatment of diazo compound 1048, prepared from 1047, with pentane-2,4-dione and ethyl acetoacetate, respectively [92JCS(Pl)239]. 

We were not able to obtain any cycloadduct from unactivated 2-azadienes 139 and esters of acetylenedicarboxylic acid. However, we found that 139 did cycloadd to typical electron-poor dienophiles such as esters of azodicarboxylic acid and tetracyanoethylene (Scheme 62). Thus, diethyl and diisopropyl azodicarboxylates underwent a concerted [4 + 2] cycloaddition with 139 to afford in a stereoselective manner triazines 278 in 85-90% yield (86CC1179). The minor reaction-rate variations observed with the solvent polarity excluded zwitterionic intermediates on the other hand, AS was calculated to be 48.1 cal K 1 mol-1 in CC14, a value which is in the range of a concerted [4 + 2] cycloaddition. Azadienes 139 again reacted at room temperature with the cyclic azo derivative 4-phenyl-1,2,4-triazoline-3,5-dione, leading stereoselectively to bicyclic derivatives 279... 

Higher alkylene oxylated derivatives of isocyanuric acid were claimed to be useful for poly(ester-imide) preparations [43], and also l,3,5-tris(2-hydroxye-thyl)-hexahydro-l,3,5-triazine-2,4-dione, prepared by reacting ethylene oxide and hexahydro-l,3,5-triazine-2,4-dione [44]. No wire enamels made from these polyols have been seen on the market. 

A few triazinamines can be treated with chlorine in the presence of sodium hydroxide to form the corresponding A-chlorinated ammelides,16,17 ammelines18 and melamines,19,20 e.g. the formation of ammelide derivative 4 [/V-chlorinated 6-amino-1,3,5-triazine-2,4(1 //,3//)-dione] from 3.17... 

Morpholino-6-phenyl-l,2,4-triazin-5(2//)-one (190) afforded the 4-methyl derivative (191) upon treatment with methyl iodide, which with water gave 4-methyl-6-phenyl-l,2,4-triazine-3,5(2/f,4//)-dione (192). 3-Morpholino-5,6-diphenyl-l,2,4-triazine (193) was isolated from the reaction of (190) with phenylmagnesium bromide (Scheme 37) <88LA141>. 

The C-C-C-N-N-N mode b of cyclization is represented by the cyclization of l-aryl-3-alkyl- (or aryl-) (3-hydro-xypropyO-triazenes giving 3,4,5,6-tetrahydro-l,2,3-triazinium salts 31 (Equation (103), Section 9.01.9) and by the preparation of l-alkyl-l,4,5,6-tetrahydro-l,2,3-triazines 30 (Equation 104). There is flexibility in the choice of substituents (alkyl, aryl). Highly functionalized 2,3,4,5-tetrahydro-l,2,3-triazin-4,5-diones (CA 2,3-dihydro-l,2,3-triazine-4,5-diones) 41 are available from the cyclization of 3-diazo-2-oxopropionic acid derivatives, but variation seems to be limited to the choice of the N-3 substituent (Equation 106). 

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