Pyrimidines 1.3.5- triazine

In contrast, some substituted anilines, e.g. 2-nitroaniline,143 2-chIoro-4-(trifluoromethyI)ani-Iine,143 benzene-1,3-diamine,150 or 4-chlorobenzene-1,3-diamine,150 give only very low yields of product or formed tars under the fluorination conditions. The diazotization followed by in situ fluorodediazoniation of the corresponding diazonium salts have been systematically studied in hydrogen fluoridc/base solutions of different composition to ascertain the most important influences on the reaction.329 Besides numerous examples of substituted anilines, various derivatives of pyridine, pyrimidine, 1.3,5-triazine, and benzthiazole have been included in these investigations (yields 45—99%). 

The relative nitrogen screening constants of pyridine, pyrazine, pyridazine, pyrimidine, 1,3,5-triazine and 1,2,4,5-tetrazine show a very good linear correlation with theoretical values of the local paramagnetic term calculated by the AEE approximation. (47) A similarly satisfactory... 

N-Heterocyclics Pyrrole Pyridine Indole Quinoline Isoquinoline Carbazole Acridine Pyrimidine 1,3,5-Triazine... 

Among its inhibitors are methotrexate (MTX), trimethoprim, and other derivatives of pyrimidines, triazines, pteridines, and related heterocyclic compounds. Some of these inhibitors, such as MTX, bind more tightly to Escherichia coli enzyme than does the substrate dihydrofolate. This fact has been attributed to ion-pair formation between protonated MTX and a negative carboxyl, presumably Asp-27, as well as to hydrophobic interactions.33... 

Purines, pyrimidines, triazines as components of quadruple hydrogen-bonded systems 03CC5. 

Ruthenium(II) A range of complexes of the type [Ru(L)(NH3)j] + (e.g. L = pyridine, pyridazine, pyrazine, pyrimidine,triazine, 2-cyanopyridine, 3-cyanopyridine, 4-cyan-opyridine, 2-, 3- and 4-RC(0)-substituted pyridines (R = CHMe2, CH2Et, CHjPr, OMe, NH2, OH, H, Ph ), IV-methylpyrazine, 4,4 -bipyridine, l,2-bis(4 -pyridyl)ethylene," hyp-oxanthine, guanine, xanthine,4-dimethylaminopyridine" ) have been prepared by reaction of [RuCl(NH3)j]Cl2 with a Ag" salt (AgOjCCF3 is often used) followed by zinc amalgam reduction... 

The strategies described in Schemes 4.6.S-4.6.9 thus combine efficiently a novel sulfur-based safety-catch linker strategy, multigeneration construction of thio-linked pyrimidines with a multidirectional cleavage procedure. This approach should prove successful for the solid-phase synthesis of a whole range of nitrogen-containing heterocycles such as pyrimidines, triazines, imidazoles, benzimidazoles. 

The earliest examples of coordination polymers constructed through the node-and-spacer approach utilized metal ions as nodes and neutral N-donor ligands as spacers. Examples of neutral N-donor ligands utilized in the construction of coordination polymers include pyrazine, 4,4 -bipyridine, ° pyrimidine, triazine, and hexamethylenetetramine (HMTA) (Figures 4-6). Examples of permanently porous MOFs based on neutral N-donor ligands are scarce, mainly due to the relatively flexible nature of the N-M bonds around the metal center.In addition, framework interpenetration is commonly observed in this class of coordination polymers, limiting the maximal attainable pore size in isoreticular compounds constructed through expansion of the linker. ... 

C=N- i benzodiazepines, pyridines, quinolines, acridines, pyrimidines, triazines, oximes, hydrazones, semicarbazones... 

We then synthesized 4,6-disubstituted 1,3,5-triazine analogs. Substituent effects for the triazine derivatives were similar to the pyrimidines. However, in contrast to the pyrimidines, triazines were selective to grasses. 

The heterocyclic intermediates for these active sulfonylurea herbicides are not herbicidal. Sulfonylureas of known herbicidal heterocyclic amines such as atrazine or metribuzin are usually similar in activity, but less active than the parent amine. They do not have the same mode of action, potency, or selectivity characteristic of this class of pyrimidine/triazine sulfonylureas. 

Replacement of one or more of the thiophene rings of a-T by phenyl, pyridine, pyridiniun pyrimidine, triazine led to noticeable decrease in postemergence activity. 

Photochemical properties of azido derivatives of six-member aza-heterocycles (pyridine, pyrimidine, triazine, quinoline, acridine) are discussed. Data on the stmcture of the reaction products formed under photolysis of azides in different conditions (solvent, temperature, additives), and also data on the matrix isolation spectroscopy of heterocyclic nitrenes, including high-spin nitrenes, produced by low-temperature photolysis of the corresponding azides are shortly examined. 

A large variety of chloride or sulfonate-substituted heteroarenes can be subjected to iron-catalyzed cross-coupling. This holds true for pyridines, pyrimidines, triazines, quinolines, isoquinolines, carbazoles, purines, pyridazines, pyrazines, quinoxalines, quinazolines, uracils, thiophenes, and benzothiazoles. In the pyridine system the presence of leaving groups of different reactivity has been demonstrated to allow for sequential introduction of different alkyl groups (Scheme 4—220). ... 

Although all the rings in Figure 1 contain six tt-electrons, the accumulation of electronegative nitrogen atoms in the polyaza structures leads to hydrolytic as well as thermal instability. This is noticeable in pyrimidine, and marked in the triazines and tetrazine. Some stability can be conferred by appropriate substitution, as we shall outline later. 

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>. 

Pyrimidin-5-amine, 4-methylamino-synthesis, 3, 121 Pyrimidin-5-amine, 4-oxo-purfne synthesis from, 5, 582 Pyrimidinamines acylation, 3, 85 alkylation, 3, 86 basic pXa, 3, 60-61 diazotization, 3, 85 Dimroth rearrangement, 3, 86 electrophilic reactions, 3, 68 Frankland-Kolbe synthesis, 3, 116 hydrolysis, 3, 84 IR spectra, 3, 64 N NMR, 3, 64 nitration, 3, 69 Principal Synthesis, 3, 129 reactivity, 3, 84-88 structure, 3, 67 synthesis, 3, 129 Pyrimidin-2-amines alkylation, 3, 61, 86 basic pK , 3, 60 diazotization, 3, 85 hydrogenation, 3, 75 hydrolysis, 3, 84 mass spectra, 3, 66 Pyrimidin-4-amines acidity, S, 310 alkylation, 3, 61, 86 basic pXa, 3, 61 Schifi base, 3, 85 synthesis, 3, 110, 114 1,3,5-triazines from, 3, 518 Pyrimidin-5-amines basic pXj, 3, 61 hydrogenation, 3, 75 reactions... 

More recently, Neunhoeffer showed that 1,3,5-triazines 16 could react with electron rich dienophiles, such as 17, to produce pyrimidines 18. 

The formal derivation of the analogs, described in the foregoing, represents, from the point of view of systematic organic chemistry, a shift to the derivatives of other heterocyclic systems. In the case of pyrimidine aza analogs we arc dealing with derivatives of symmetrical or asymmetrical triazine in the case of purine aza analogs, the derivatives produced are those of imidazo[4,5]-i -triazine and z -triazolo [4,5-d] pyrimidine. 

All these findings, as well as the similarity of UV spectra - caused dioxotetrahydrotriazine to be classified as the simplest member of the formerly known 6-substituted derivatives. These derivatives are not interesting in connection with the analogs of natural pyrimidine bases and have been reviewed elsewhere. The structure of allantoxaidine and its appurtenance to the triazine series have been recently demonstrated by its unequivocal synthesis. 

The pyrimidine compounds are known to undergo a rearrangement of the 0-alkyl derivatives to the iV-alkyl ones. The methoxy derivatives of 1,3,5-triazine display a similar behavior. On applying methyl iodide to 2,4-dimethoxy-l,3,5-triazine one of the methyl groups is shifted giving rise to l-methyl-4-methoxy-derivative (22). This compound was also obtained by methylation of 4-methoxy-2-oxo-1,2-dihydro-1,3,5-triazine (18) with diazomethane. At higher temperature (100°C) in presence of methyl iodide a shift of both methyl groups takes place and methiodide is formed simultaneously (23). Similarly,... 

In all types of nomenclature based on triazine the numbering of the substituents is shifted by one as compared with the nomenclature of 6-aza analogs of pyrimidines. 

The chemistry of the 6-aza analogs of pyrimidine bases which has been developed from the biochemical aspect since about 1956 was based on work reported in relatively numerous older papers. In spite of the fact that 6-azauracil was prepared only in 1947 and suitable syntheses were described only quite recently, substances of this type and methods of their preparation had been known for a long time. The chemistry of 6-aza analogs of pyrimidine bases is therefore relatively closely linked with the chemistry of the 1,2,4-triazine derivatives. 

Chemical and enzymatic ribosidization of the aza analogs of the pyrimidine bases thus take different routes. These results and independent earlier studies of the alkylation of 6-azauraciE led to the conclusion that, in order to achieve ribosidization in position 1 (i.e., position 2 of the triazine ring), the position 3 (4 of the triazine ring) must be protected. ... 

Reagent P-K a 2-Chloro- pyrimidine 2-Chloro- 3-nitro- pyridine 2-Chloro- 5-nitro- pyridine 2,4-Dichloro- phenylamino-s-triazine ... 

---