1.3.5- Triazine 2.4- dimethoxy

The pyrene derivative (17) [3271-22-5] is obtainable by the Friedel-Crafts reaction of pyrene with 2,4-dimethoxy-6-chloro-j -triazine, and is used for brightening polyester fibers (75). 

Flament et al made use of the partial replacement of two chlorine atoms in cyanuric chloride (12) with methoxyl groups, the 2,4-di-methoxy-6-chloro-l,3,5-triazine (13) formed was dehalogenated to 2,4-dimethoxy-1,3,5-triazine (14) and this yielded the product (2) on gentle hydrolysis. 

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,... 

A similar rearrangement accompanied by decarboxylation was described for 2,4-dimethoxy-l,3,5-triazine-6-carboxylic aeid. ... 

Other derivatives of s-triazine, in particular the 2,4-disubstituted ones, are usually prepared by total synthesis and are therefore not closely linked with the chemistry of 5-azauracil unlike the analogous derivatives of 1,2,4-triazine. 2,4-Dimethoxy-l,3,5-triazine was mentioned earlier (e.g., Section II,A,2,a), the other substances are not related to the present subject. 

Trichloro-l,2,4-triazine was reacted with menthanol and subsequently crystallized from w ater to yield 5-chloro-6-azauracil. A chloro-dimethoxy derivative appears to be an intermediate product, this being further cleaved by hydrogen chloride. No 2,4-dimethoxy derivatives have been prepared so far. 

Even polyalkoxy-s-triazines are quite prone to nucleophilic substitution. For example, 2,4,6-trimethoxy-s-triazine (320) is rapidly hydrolyzed (20°, dilute aqueous alkali) to the anion of 4,6-dimethoxy-s-triazin-2(l )-one (331). This reaction is undoubtedly an /S jvr-4r2 reaction and not an aliphatic dealkylation. The latter type occurs with anilines at much higher temperatures (150-200°) and with chloride ion in the reaction of non-basified alcohols with cyanuric chloride at reflux temperatures. The reported dealkylation with methoxide has been shown to be hydrolysis by traces of water present. Several analogous dealkylations by alkoxide ion, reported without evidence for the formation of the dialkyl ether, are all associated with the high reactivity of the alkoxy compounds which ai e, in fact, hydrolyzed by usually tolerable traces of water. Brown ... 

The highly electrophilic 1,3,5-triazinylnitrene generated by photolysis of 2-azido-4,6-dimethoxy-l,3,5-triazine (24) does, however, bring about ring expansion of benzene to l-(4,6-dimethoxy-1,3,5-triazin-2-yl)-1//-azepine (25) in moderate yield.168... 

Giacomelli et al. constructed 3-propylisoxazole-5-yl-methanol via a [3-1-2] cycioaddition (Fig. 15) [158]. Nitrobutane was converted to nitrile oxide in the presence of 4-(4,6-dimethoxy [1,3,5]triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) and catalytic 4-dimethylaminopyridine (DMAP). Trityl chloride resin-bound propargyl alcohol was employed as the dipolarophile to trap the nitrile oxide, forming the cyclo adduct isoxazole ring under unusually mild conditions (i.e., microwave irradiation at 80 °C for five times 1 min). Disappearance of the starting material was monitored by FT-IR. 

The synthesis of 2,4,6-trisubstituted-l,3,5-triazines has been reviewed <06MI81>. Reaction of an activated form of carboxylic acids 20 with zinc dimethyl imidodicarbonimidate 21 led to 4,6-dimethoxy-l,3,5-triazines 22 in high yields <06S2845>. 

Generation of nitrile oxides can also proceed by the action of neutral or basic reagents, for example, tert-butyl carbonate (72) or 4-(4,6-dimethoxy-l,3,5-triazin-... 

Chloro-4,6-dimethoxy-l,3,5-triazine (100) reacts with iV-methylmorpholine at 20 °C to yield an isolable quaternary triazinylammonium salt (101 R = Me, R, R = C4H8O). This salt can then be reacted with a carboxylic acid to yield a 2-acyloxy-4,6-dimethoxy-l,3,5-triazine (102), which, in turn, can be reacted with an amine to yield an amide (103). This sequence of reactions provides an explanation for the activation (formation of reactive ester) of the carboxylic acid function by 2-chloro-4,6-disubstituted-l,3,5-triazines (100) in the presence of hindered amines. Several other hindered amines may replace iV-methylmorpholine in the process, but unhindered amines such as triethylamine and tributylamine were inactive. ... 

As can be seen, the pathway from the cyclohexadienone to the ortho-rearranged phenol does not imply a jump over an energy barrier (34 kcal/mol), but a tunneling from the vibrational energy levels located at E(vo) = 0 kcal/mol and E(vi) = 3.9 kcal/mol (4.4 kcal/mol for the deuterated compound). Analogous results have been reported for the photo-Fries rearrangement of 2,4-dimethoxy-6-( ara-tolyloxy)-v-triazine (28) to give 2,4-dimethoxy-6-(2-hydroxy-5-meth-ylphenyl)-v-triazine (29) (Scheme 11) [43]. 

Rather surprisingly the only polycyclic ring system to have found significant commercial application in FBAs is pyrene. The triazinyl derivative (3.64), which is synthesised by a Friedel-Crafts reaction between pyrene and 2-chloro-4,6-dimethoxy-l,3,5-triazine, is an important brightener for polyester and cellulose acetate. 

New reagents, 2-acyloxy-4,6-dimethoxy-133-triazines, have been used as acyiating agents for the synthesis of esters from primary, secondary and tertiary alcohols. Because of mild... 

Formation of l-aryl-l//-azepines is rare and occurs only with those arylnitrenes made sufficiently electrophilic by an electron-withdrawing, e.g. CN, N02 or CF3, ortho or para substituent. Even so, these docile nitrenes attack only electron-enriched arenes (e.g. mesity-lene or Af,Af-dimethylaniline) and are of minor synthetic importance (B-73MI51600). More reactive are 7r-deficient heteroarylnitrenes, and moderate yields (15-40%) of 1-heteroaryl-l//-azepines, e.g. (228 R=4,6-dimethoxy-l,3,5-triazin-2-yl), may be obtained by the photodecomposition of 2-azido-4,6-dimethoxy-l,3,5-triazine in a variety of aromatic substrates (81BCJ301). Interestingly, intramolecular insertion of arylnitrenes into arenes is more common and has been used for the synthesis of fused azepines, e.g. the azepinoindoles (229) from o-azidodiphenylmethanes (81JCS(P1)1132). 

Analogous reactions with perfluoro(isopropyl-l,3,5-triazine) and per-fluoro(diisopropyI-l,3,5-triazine) with CsF yielded adducts 116 and 117, respectively, which were detected by 19F-NMR. Use of potassium fluoride, either alone or associated with 18-crown-6, did not lead to the formation of the adducts. In contrast, from tris(perfluoroisopropyl)-l,3,5-triazine no adduct was detected. This is quite interesting because it would indicate the importance of the gem-difluoro substitution to stabilize the adduct,160 in analogy with the effect of gem-dimethoxy substitution.76... 

The reduction of chloro compounds (308), mainly by catalytic means, has been used for the synthesis of a variety of 1,2,4-triazines. For instance, the methoxy- and dimethoxy-triazines (309-311) have been made from the trichloro compound (73) by treatment with methoxide, and hydrodechlorination of the methoxy-halo compounds (66CB1113). 

Weber et al. have reported that the condensation product (26) of the reaction between methyl cyanoacetate and 6-chloro-2,4-dimethoxy-l,3,5-triazine exists as two tautomeric forms in rapid equilibrium. The ester is enolized readily (A). The second exchange involves the breaking of an intramolecular hydrogen bond (B) (Scheme 5) (78RTC107). 

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