Heterocycles triazole derivatives

An interesting application of a phosphorus ylide in heterocyclic synthesis is in a ring annulation. The diazopyrazole (592) when treated with various phosphorus ylides gave the 3//-pyrazolo[5,l-c][l,2,4]triazole derivatives (593) with elimination of triphenylphosphine (79TL1567). 

Rearangement of furoxans leads to the formation of new heterocyclic systems derivatives of triazoles, diazoles, isoxazoles, and pyrimidinones. For example, on the basis of the experimental results using labeled compound 52-15N , the formation of 8-phenyltheophylline 53, the 1,3-dimethylalloxazines (54 n = 0, 1), and l,3,7,9-tetramethyl-l//,9//-pyrimido[5,4-g]-pteridine-2,4,6,8-tetraone 55 in the thermal reaction of the iV-oxide 52 with benzylamine, aniline, or piperidine and the generation of NO or NO-related species in the reaction with iV-acetylcysteamine were reasonably explained by... 

Abstract In this chapter, selected results obtained so far on Fe(II) spin crossover compounds of 1,2,4-triazole, isoxazole and tetrazole derivatives are summarized and analysed. These materials include the only compounds known to have Fe(II)N6 spin crossover chromophores consisting of six chemically identical heterocyclic ligands. Particular attention is paid to the coordination modes for substituted 1,2,4-triazole derivatives towards Fe(II) resulting in polynuclear and mononuclear compounds exhibiting Fe(II) spin transitions. Furthermore, the physical properties of mononuclear Fe(II) isoxazole and 1-alkyl-tetrazole compounds are discussed in relation to their structures. It will also be shown that the use of a,p- and a,C0-bis(tetrazol-l-yl)alkane type ligands allowed a novel strategy towards obtaining polynuclear Fe(II) spin crossover materials. 

Fused heterocyclic systems derived from 3-mercapto-l,2,4-triazole can be obtained by heterocyclization of 4-allyl-l,2,4-triazole-3-thione derivatives by treatment with halogens or mineral acids <1996T791>. Compounds 342 react with bromine yielding thiazolium halides 28 in good yield (Equation 64) <2000RJOC1033>. 

Most syntheses of TPs start either from a 1,2,4-triazole derivative or from a pyrimidine residue and need annulation of a second heterocyclic ring. Preferably 5-amino-1,2,4-triazoles (AT) and 2-hydrazinopyrimidines (HP), respectively, are used as starting synthons. 

Benzyl triazole, C9HgN3 mw 159.19, N 26-40%. This compd presumably exists as benzyl derivs of the isomeric, heterocyclic triazole, for example /N=CH N=N... 

All remaining Anil Syntheses involving 1,2,3-triazoles have been performed with Schiff s bases derived from 4-formyl- or 2- or 4-(p-formylphenyl)-2/f-l,2,3-triazole and chloroanilines, which react with both carbocyclic and heterocyclic / -tolyl derivatives. Carbocyclic... 

Alcohols containing nitrogen heterocycles are also smoothly oxidized to the corresponding carbonyl compounds. These heterocycles include pyridine, imidazole and triazole derivatives. 

A study of ketene A, O-acetals has shown that such compounds derived from lactam acetals may be used in the preparation of larger heterocyclic systems via reaction with a 1,3-dipolar species, the initial cycloadducts stabilizing their structures by aromatization. Pyrrolo[2,3-i/]-l,2,3-triazole derivatives, however, do not undergo such elimination reactions and stable cycloadducts may be obtained. Thus, the lactam acetals (133) give the ketene A,0-acetals (134), which on reaction with p-nitrophenyl azide yield substituted pyrrolo[2,3-d]-l,2,3-triazole derivatives (135) <86CB359l>. 

Benzoxazole and triazole derivatives 67 and 73b showed the highest antiatherosclerotic activity among all the investigated silacyclic S-sub-stituted heterocycles in mice maintained on high-cholesterol diet. They protected against an increase in serum low-density lipoprotein level and... 

Cycllzations of (16) as represented in Scheme 7 can afford triazole derivatives (17) or isomeric triazoles (18) or other heterocycles (19). The claimed isolation of two stable tautomers of (17) has been shown to be in error by demonstration of the isomerization involving (17) and (19 X = 0) (60la(638)136). 

Bridge complexes with heterocyclic ligands, derivatives of triazoles, oxa- and thiadiazoles, pyridazine, phthalazine, etc. 04CRV349. 

These are added to paper, plastics and detergents to increase the whiteness by absorbing UV light and emitting blue light. Many optical brighteners are stilbene derivatives, but a number of heterocyclic ring types are also important, for example the oxazole and triazole derivatives shown below, 1,3,5-triazines and... 

Oxidation of heterocyclic amino derivatives yields various reaction products depending on the structure of the amine. 4-Benzylamino-3-methyl-4//-1,2,4-triazole is oxidized with DCT in chloroform to give the azomethine derivative 110 (69ZC325). l-Amino-4,5-diphenyl-l,2,3-triazole under the action of CBT forms diphenylacetylene 2-aminobenzotriazole yields cis, cw-l,4-dicyanobuta-l,3-diene and 1-aminobenzotriazole yields a mixture of chlorobenzene and o-dichlorobenzene. Oxidation of 1-aminobenzotriazole in the presence of tetraphenylcyclopentadienone leads to 1,2,3,4-tetraphenylnaphthalene via benzyne intermediate [68JCS(CC)1305 69JCS(C)1474] (Scheme 101). 

This reaction principle has considerable scope, as shown by the synthesis of various heterocyclic annu-lated 1,4-benzodiazepines. [l,2,3]Triazolo[l,5-fl][l,4]benzodiazepines 23 are prepared from triazole derivatives 22 which are accessible by a 1,3-dipolar cycloaddition of o-azidobenzophenones with (aminomethyl)alkines pyrrolo[2,l-c][l,4]benzodiazepines 25 are formed from l,2-dihydro-3,l-benzoxazinediones 24 and proline ... 

J. Penninger, K. Wippermann and J.W. Schultze. Molecular structure and efficiency of triazole derivatives and other heterocyclics as corrosion inhibitors for copper. Werkstoffe und Korrosion, 1987, Vol. 38, pp. 649-659. 

Oxidation of Hydrazones, Alkylhydrazones, A-Amino Heterocycles, A-Aminophthalimidates, and Aldazines. The oxidation of hydrazones to diazo compounds is not a generally useful reaction but it was uniquely effective in the oxidation of a triazole derivative (eq 36). ... 

Heterocyclization of acylthiosemicarbazides Synthesis of pyrrole, thia-zole, thiadiazole, thiadiazoHdine, and triazole derivatives and fused heterocycles 12JHC38. 

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