Triazinone ring

In the literature, various other types of resin preparation procedures are described, e.g. yielding uron structures [20-22] or triazinone rings in the resins [23,24]. The last ones are formed by the reaction of urea and an excess of formaldehyde under basic conditions in the presence of ammonia or an amine, respectively. These resins are used to enhance the wet strength of paper. 

Thermolysis of an o-halo-semicarbazide (9.4, R = H) at 175-180 C produced a new reduced triazinone ring, but when N of the semicarbazide group carried... 

Figure 1. Different patterns of biodegradation resulting from microbial adaptation. (A) Adaptation to p-nitrophenol in Lulu aquifer samples at 529 ng/mL, but not at 14 ng/mL (41). (B) Adaptation to the triazinone-ring of metribuzin, evidenced by an increasing mineralization rate over time in the surface soil, but not in the subsurface soils (351. (C) Adaptation to EPTC after long-term EPTC use (12). (Reproduced with permission from Ref. 12. 15, 43. Copyrights 1988, 1989, 1987 Weed Science Society of America, American Society of Agronomy, and American Society for Microbiology, respectively)...

Herbicides containing the asymmetric 1,2,4-triazinone ring were developed in the research laboratories of the Bayer AG (Schmidt et al., 1975a Schmidt et al., 1975b). 

Nickel/hydrazine o-Aminocarboxylic acid amides from triazinone ring... 

The synthesis of this ring system was achieved by the reaction of the ketene aminal 79 with 3-morpholino-l-ethyl-l,2,4-triazinium tetrafluoro-borate 78 to give 80 (89IZV494). Cyclization of 78 with the bifunctional nucleophile 81 gave the pyrrolo[3,2-e][l,2,4]triazinones 82 (88TL1431). This reaction represents the first example of orthocyclization onto the 1,2,4-triazine ring by the addition of dienophiles at C-5,6 (Scheme 20). 

A regioselective synthesis of 2-amino[l, 2,4]triazinones 708 was reported (82JHC1583 83JHC1671) by reaction of 706 with 0-(2,4-dinitrophenyl)-hydroxylamine 707 as an amino transfer agent. Subsequent reaction of 708 with ammonia or amines, followed by ring closure with formic acid, provided 709. 

A facile ring closure at the N-l nitrogen of the 1,2,4-triazine ring occurs to afford triazolo[3,4-/][l, 2,4]triazinones 962 when 961 reacted with acids,... 

Pyrrolo[l,2-rf [l,2,4]triazinones 21 were synthesized from methyl ester of /ra j-4-hydroxy-L-proline 72. The synthetic route involved formation of hydrazones followed by cyclisation with orthoesters <1998BMC349>. Similar reactions have been developed with 3-benzylindole-2-carbohydrazides 73 in reaction with triethyl orthoformate, giving the corresponding ring systems indolo[l,2-r][ 1,2,4]triazin-4-oncs 74 <2004JHC7>. 

A 1,5-dipolar cyclization route to [l,2,4]triazolo[4,3-3][l,2,4]triazinones has been elaborated by Shawali and Gomha <2002T8559>, and the results are summarized in Scheme 40. The direct starting compound for the ring-closure reaction is the active intermediate iminonitrilimine 196, which is formed upon oxidation of the hydrazone 195. Intermediate 196 undergoes 1,5-dipolar cyclization and affords the ring-closed product 197. The transformation has been carried out both in the case of the N-unsubstituted (R= H) and in the case of the A-methyl (R = CH3) compound. 

Scheme 44 also shows two further synthetic routes to [l,3,4]thiadiazolo[2,3-c][l,2,4]triazinones. Reaction of the 3-mercapto- or 3-methylsulfanyltriazinone 221 (R1 = H or R1 = Me) with a set of isothiocyanates was reported to give the 2-amino-substituted fused ring system 222 in medium to good yield (36-84%) <1997JHC1351>. Derivative 223 was described to undergo cyclization to a fused thiadiazole 224 by treatment with carbon disulfide in the presence of potassium hydroxide in ethanol <2001PHA376>. 

New derivatives of [l,2,4]triazolo[3,4-/][l,2,4]triazinones have been synthesized by earlier established cyclization methods <2006JHC889>. Alkylation of the 3-mercapto group of this ring system has also been reported <2006MI169>. 

A Russian team, when investigating the ring-closure reaction to some tiazolo[3,2- ][l,2,4]triazinones 45 and 46, carried out AMI calculations for these molecules <2000ZOB650>. With the help of the quantum-chemical results, infrared (IR) spectra of these compounds have been calculated and compared with the experimentally observed spectra. Thus, clear differentiation is possible between the two tautomeric structures. 

Theoretical calculations were carried out for the rationalization of the ring closure reactions yielding thiazolo[2,3-7][l,2,4]triazinones 47 <2003PS1143>. PM3 and AMI methods were applied which revealed that the observed regioselective cyclization is in accordance of the charge control of the reaction. 

Rusinov et al. <1996ZOR770> found that the nitro-substituted pyrazolo[5,l-c][l,2,4]triazinone compound 74 undergoes ring opening when boiled in water to yield a hydrazone 75. During the reaction, carbon dioxide is eliminated. 

The ring opening of the oxazolotriazinium salt 86 with sodium dithiocarbamate was reported by Dovlatyan et al. <1996KGS1417>. The reaction takes place in water at room temperature to yield a dithiocarbamoylethyl-substituted triazinone 87. 

Ring closure to a fused furan was carried out by Kruglenko et al. <1998KGS258> the fused triazinone derivative 105 was treated with thionyl chloride under reflux conditions in chloroform to yield the tricyclic compound 106 in excellent yield. 

Hydrazinobenzimidazole derivative 336 was treated with oxocarboxylic acids to give a hydrazone 337 which underwent ring closure to the fused triazinone 338 <2000JME96, 2001JME316>. Reaction with dialkyl oxalate allowed the synthesis of the triazinedione derivative 339 <2001JME4359>. 

Other examples of nucleophilic attack leading to ring opening/recyclization are the formation of triazolidinedione (70) from oxadiazolinone (62e) and methylhydrazine, presumably via intermediate (62f) <89JHC23l>, and the conversion of phenylhydrazones (62g) into triazinones (71) in the presence of base <92JHC959>. 

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