The formation of 1,2,4-triazolylimidazolidine-2,4-diones in reactions of 3-aryl-1,2,4-triazin-5(2H)-ones with alkylureas

Recyclization of the addition products of alkylureas to 3-aryl-1,2,4-triazin-5(2H)-ones affording 1,2,4-triazole derivatives was found to occur in Ac₂O.     

Synthesis of 4-Amino-6-R-4,5-dihydro-3-phenacylthio-1,2,4-triazin-5-ones and 8H-3-R-7-Aryl-1,2,4-triazino[3,4-b][1,3,4]thiadiazin-4-ones

A study was carried out on the reaction of 4-amino-6-R-2,3,4,5-tetrahydro-3-thioxo-1,2,4-triazin-5-ones with halo ketones in alkaline media to yield 4-amino-6-R-4,5-dihydro-3-phenacylthio-1,2,4-triazin-5-ones, which then convert to 8H-3-R-7-aryl-1,2,4-triazino[3,4-b][1,3,4]thiadiazin-4-ones.     

GIAO/DFT studies on 1,2,4‐triazole‐5‐thiones and their propargyl derivatives

Density functional theory (DFT)/Becke–Lee–Yang–Parr (B3LYP) and gauge‐including atomic orbital (GIAO) calculations were performed on a number of 1,2,4‐triazole derivatives, and the optimized structural parameters were employed to ascertain the nature of their predominant tautomers. ¹³C and ¹⁵N NMR chemical shifts of 3‐substituted 1,2,4‐triazole‐5‐thiones and their propargylated derivatives were calculated via GIAO/DFT approach at the B3LYP level of theory with geometry optimization using a 6‐311++G** basis set. A good agreement between theoretical and experimental ¹³C and ¹⁵N NMR chemical shifts could be found for the systems investigated. The data generated were useful in predicting ¹⁵N chemical shifts of all the nitrogen atoms of the triazole ring, some of which could not be obtained in solution state ¹⁵N HMBC/HSQC NMR measurements. The energy profile computed for the dipropargylated derivatives was found to follow the product distribution profile of regioisomers formed during propargylation of 1,2,4‐triazole thiones. Copyright © 2013 John Wiley & Sons, Ltd.     

The rearrangement of 3,4-disubstitued-Δ2-1,2,4-oxadiazolin-5-thiones

The light and metal catalysed rearrangement of 3,4-disubstituted-Δ²-1,2,4-oxadiazolin-5-thiones (3) to the corresponding Δ²-1,2,4-thiodiazolin-5-ones (4) is described. The thermal stability of (3) is in great great contrast to the ease of rearrangement of the acyclic analogues. The rearrangement of (3) and (4) under electron impact are described.     

13C NMR spectra of some 1,2-disubstitutedN-vinyl-1H-1,2,4-triazoles

¹³C NMR spectra (20 and 75 MHz, in DMSO-d₆) of a series of 1,3-diaryl-3-(1H-1,2,4-triazol-1-yl)- and 1,3-diaryl-2-(1H-1,2,4-triazol-1-yl)prop-2-en-1-ones were registered. It was shown that the chemical shifts of both the carbon atom of the alkene group and C(3) reflect regio- and stereoisomerism of these compounds. Taking this into account the isomeric structures of several 1,3-diaryl-3-(1H-1,2,4-triazol-1-yl)prop-2-en-1-ones were identified and the configurations relative to the double bond of a number of 1,3-diaryl-2-(1H-1,2,4-triazol-1-yl)prop-2-en-1-ones were determined.     

New silica hybrids elaborated by sol-gel process from bifunctional thiadiazole and 1,2,4-triazole precursors

New hybrid materials were synthesized from an inorganic precursor, (tetraethoxysilane: TEOS) and bifunctional organic precursors through the sol-gel process. Indeed, monolithic and transparent hybrid gels were obtained by the reaction of tetraethoxysilicate (TEOS) with 1,2,4-thiadiazole-3,5-diamine (1), 5-amino-1,3,4-thiadiazole-2-thiol (2), and 1H-1,2,4-triazole-3-thiol (3) in ethanol as solvent, using chloric acid (HCl 10^?1M) as catalyst. It is shown that TEOS has been cross-linked with bi-functional heterocyclic compounds: (1), (2) and (3) leading to the formation of transparent and colorous gels. The characterization was realized by infrared, ²⁹Si and ¹³C CP MAS NMR. The xerogels morphology and texture were studied by scanning electron microscopy (SEM) and Brunauer – Emmet – Teller method (BET). The obtained results show that organic adducts (1), (2) and (3) react with TEOS leading to gels in which Si–N and Si–S bridges were formed. According to N₂-physisorption results, xerogels are mesoporous with specific surface area varied from 105 to 312 m²g^?1 and their isotherms are classified as type IV. The optic and magnetic properties of hybrids were studied respectively by UV-Vis spectroscopy and RPE. This study showed that all materials are paramagnetic semiconductors.     

Efficient synthesis of 1,2,4-oxadiazine-5-ones via [3+3] cycloaddition of in situ generated aza-oxyallylic cations with nitrile oxides

1,2,4-Oxadiazin-5-ones were prepared via [3+3] cycloaddition of in situ generated aza-oxyallylic cations with nitrile oxides in good yields and excellent functional group compatibility. This efficient transformation is metal-free and is promoted by an inorganic base Cs₂CO₃. In addition, this reaction features simple-operation, mild conditions, and high regioselectivity.     

Reactions of 3-nitro-1,2,4-triazole derivatives with alkylating agents. 5. Selective synthesis of 1,4-dialkyl-and 1,4,5-trialkyl-3-nitro-1,2,4-triazolium salts from 1-alkyl-and 4,5-dialkyl-3-nitro-1,2,4-triazoles and dialkyl sulfates

Interaction of N₍₁₎-alkyl-substituted 3-nitro-5-R-1,2,4-triazoles with dialkyl sulphates proceeds selectively and results in the respective salts of 1,4-dialkyl-, 1,4,5-trialkyl-3-nitro-1,2,4-triazoliums. The reaction of N₍₄₎-alkyl-substituted 3-nitro-5-R-1,2,4-triazoles yields the mixtures of the salts of 1,4-dialkyl-, 1,4,5-trialkyl-3-nitro-1,2,4-triazoliums and 1,4-dialkyl-, 1,3,4-trialkyl-1,2,4-triazol-5-ones with predominance of quaternary salts. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 927–934, June, 2007.     

Hydroacridines: Part 33. An experimental and DFT study of the 13C NMR chemical shifts of the nitrosamines derived from the six stereoisomers of tetradecahydroacridine

The paper presents the experimental and DFT-calculated values of the ¹³C NMR chemical shifts of the six stereoisomers of tetradecahydroacridine and of the corresponding nitrosamines. Performing the DFT calculations using several combinations of functional and basis sets, it was found that the best experimental-calculated agreement was obtained for OPBE/6–311++G (dp) method. Considering the effect of N-nitrosation upon the ¹³C NMR chemical shifts of the C-α carbons of secondary amines, it was found that if following nitrosation both C-α carbons are shifted upfield or both are shifted downfield, then the resulted nitrosamine will have a sterically strained ─N═O group. If, however, one of the C-α is shifted upfield and the other is shifted downfield, then the ─N═O group will be strain-free or weakly strained. Our calculations predict strain energies of about 10–15 kcal mol⁻¹ in the first case and ≈0–6 kcal mol⁻¹ in the latter.     

Easy formation of SNH products in reactions of indoles and pyrroles with 3-aryl-1,2,4-triazin-5(2H)-ones in the presence of tosyl chloride

The reactions of 3-aryl-1,2,4-triazin-5(2H)-ones with indoles and pyrroles in the presence of p-toluenesulfonyl chloride afforded 3-aryl-6-hetaryl-1,2,4-triazin-5(2H)-ones in high yields. The latter are products of the nucleophilic substitution of hydrogen.     

Synthesis of 4-hydroxy-4,5-dihydro-1,2,4-triazol-5-ones

Summary A series of hydroxamic acid ethoxycarbonylhydrazides was obtained by reactions of ester ethoxycarbonylhydrazones with hydroxylamine. The corresponding 3-substituted 4-hydroxy-4,5-dihydro-1,2,4-triazol-5-ones were synthesized by cyclization of these hydroxamic acid derivatives in basic medium.

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Synthesen von 4-Hydroxy-4,5-dihydro-1,2,4-triazol-5-onen

Zusammenfassung Durch Reaktion von Esterethoxycarbonylhydrazonen und Hydroxylamin wurde eine Reihe von Hydroxamsäureethoxycarbonylhydraziden gewonnen; Cyclisierung dieser Verbindungen durch Base gab die entsprechenden 3-substituierten 4-Hydroxy-4,5-dihydro-1,2,4-triazol-5-one.

     

Nucleophilic substitution of hydrogen in the reaction of 1,2,4-triazin-4-oxides with cyanamide

It was shown that cyanamide can successfully be used in reactions of nucleophilic substitution of hydrogen with 1,2,4-triazin-4-oxides in the presence of a base to give 5-cyanoimino-1,2,4-triazines. It was found by¹³C NMR spectroscopy that these compounds and their alkylation products at the cyclic nitrogen atom exist in the form of 5-cyanoimino-2,5-dihydro-1,2,4-triazines. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1128–1130, June, 2000.     

1H{15N} GHMQC study of 5,7‐diphenyl‐1,2,4‐triazolo[1,5‐a]pyrimidine and 1H, 13C and 15N NMR coordination shifts in Au(III) chloride complexes of 1,2,4‐triazolo[1,5‐a]pyrimidines

The ¹H{¹⁵N} NMR spectrum of 5,7‐diphenyl‐1,2,4‐triazolo[1,5‐a]‐pyrimidine ( 3 ) was measured by GHMQC, unambiguously assigned and compared with the spectra of 1,2,4‐triazolo[1,5‐a]pyrimidine ( 1 ) and 5,7‐dimethyl‐1,2,4‐triazolo[1,5‐a]pyrimidine ( 2 ). A series of Au(III) chloride complexes of general formula AuLCl₃, where L = 1 , 2 , 3 , was synthesized and studied by ¹HH{¹⁵N} GHMQC and ¹H{¹³C} GHMBC. Low‐frequency shifts of 72–74 ppm (¹⁵N) and 5–6 ppm (¹³C) were observed upon complexation by Au(III) ions for the coordination site N‐3 and adjacent C‐2, C‐3a atoms, respectively. The ¹³C signals of C‐5, C‐6, C‐7 and the ¹H resonances of H‐2, H‐6 were shifted to higher frequency. Comparison with analogous Pd(II), Pt(II) and Pt(IV) complexes revealed that in the case of Au(III) coordination the ¹⁵N shifts were relatively smaller, whereas those for ¹³C and ¹H were larger. Copyright © 2002 John Wiley & Sons, Ltd.     

A CONVENIENT AND GENERAL SYNTHESIS OF A NOVEL HETEROCYCLIC SYSTEM; 5H-[1,3,4]THIADIAZOLO[2,3-d] [1,2,4]TRIAZIN-5-ONES

Abstract

5H-[1,3,4]Thiadiazolo[2,3-d][1,2,4]triazin-5-ones were synthesized by cyclocondensation of 4-amino-5-mercapto-1,2,4-triazin-3-ones with a variety of carboxylic acids in the presence of phosphorus oxychloride.     

Stereoselective synthesis of dihydrothiadiazinoazines and dihydrothiadiazinoazoles and their pyrolytic desulfurization ring contraction

Intramolecular base catalyzed C-C bond formation led to exclusive stereoselective syntheses of trans-6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines, trans-7,8-dihydro-6H-[1,2,4]triazino[3,4-b][1,3,4]thiadiazin-4-ones, and trans-3,4-dihydro-2H-[1,3,4]thiadiazino[2,3-b]quinazolin-10-one. trans-6,7-Dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines isomerize slowly in CDCl₃ and more rapidly in DMSO-d₆ into the corresponding cis-stereoisomers. The other trans-6,7-dihydro-[1,3,4]thiadiazines isomerize also in DMSO-d₆ into the corresponding cis-stereoisomers. Pyrolytic conversion of these heterocyclic condensed dihydrothiadiazines into their corresponding pyrazolo[5,1-b][1,2,4]triazoles, pyrazolo[5,1-c][1,2,4]triazin-4-ones and pyrazolo[4,3-b]quinazolin-9-ones via desulfurization ring contraction is described.     

微波促进下3-(2-苯并呋喃基)-4-氨基-5-巯基-1,2,4-三唑

微波辐射条件下, 首先由2-苯并呋喃甲酰肼依次与二硫化碳和水合肼反应合成3-(2-苯并呋喃基)-4-氨基-5-巯基- 1,2,4-三唑, 进一步在微波辐射条件下由4-氨基-5-巯基-1,2,4-三唑分别与芳甲酸/芳氧基乙酸、α-溴代苯乙酮及芳醛反应以较高产率制得了相应的1,2,4-三唑并[3,4-b]-1,3,4-噻二唑、1,2,4-三唑并[3,4-b]-1,3,4-噻二嗪及4-芳亚甲基亚胺基-5-巯基-1,2,4-三唑. 产物结构经IR, ¹H NMR, MS及元素分析进行了表征.     

Reaction of 3-Arylmethylidene-3H-furan-2-ones with 3-Amino-1,2,4-triazole as a Convenient Technique to Synthesize Condensed Diazepinones

The interaction of the arylmethylidene derivatives of 3H-furan-2-ones with 3-amino-1,2,4-triazole was studied. The structure of the final products depends on reaction conditions and reagent ratio.

Direction of isomerization of 5-hydroxy-3-propargylthio-1,2,4-triazines according to 1H/15N heteronuclear multiple bond correlation (HMBC) spectra

We have studied isomerization of 6-substituted 5-hydroxy-3-propargylthio-1,2,4-triazines using base catalysis. We have used NMR correlation spectroscopy (¹H/¹⁵N HMBC spectra) to prove the structure of the regioisomer formed. The type of regioisomer formed (3,6-dimethylthiazolo[3,2-b]-1,2,4-triazin-7-one) allows us to say that isomerization occurs as a direct propynyl rearrangement. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 453–457, March, 2006.     

新型2H-噻唑[3,2-b][1,2,4]三嗪-3,7-二酮的超声辅助一锅法合成及乙酰胆碱酯酶抑制活性研究

以取代苯甲醛、溴乙腈和6-苄基-3-硫代-3,4-二氢-1,2,4-三嗪-5(2H)-酮为起始原料,在超声辅助下,一锅合成了9个新型6-苄基-2-亚苄基-2H-噻唑[3,2-b][1,2,4]三嗪-3,7-二酮类化合物,结构经_¹H NMR,_¹³C NMR和MS（ESI）表征并对其合成机理进行了初步研究。测试了目标化合物(4a~4i)的体外乙酰胆碱酯酶的抑制活性,其中4a和4d抑制活性最好,有进一步研究的价值。     

Photochemical reactions of group VIB metal carbonyls with heterocyclic Schiff bases derived from 4-amino -3-hydrazino-5-mercapto-1,2,4-triazole

The new complexes, M(CO)₅(Schiff base) [M?=?Cr; 1, Mo; 2, W; 3, Schiff base?=?4-salicylidenamino-3-hydrazino-5-mercapto-1,2,4-triazole, SAHMT, a; 4-(2-hydroxynaphthylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole, 2HNAHMT, b; 4-(3-hydroxybenzylidenamino)-3-hydrazino-5-mercapto-1,2,4- triazole, 3HBAHMT, c; 4-(4-hydroxybenzylidenamino)-3-hydrazino-5-mercapto-1,2,4- triazole, 4HBAHMT, d; 4-(5-bromosalicylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole, 5BrSAHMT, e; were synthesized by photochemical reaction of metal carbonyls M(CO)₆ (M?=?Cr, Mo, W) with new heterocyclic Schiff bases derived from 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole, a–e. The ligands and complexes have been characterized by elemental analysis, EI-mass spectrometry, FT-IR, ¹H and ¹³C-{¹H}-NMR spectroscopy. The spectroscopic studies show that Schiff bases, a–e, are monodentate and coordinate via azomethine N donor to the central metal atom in M(CO)₅(Schiff base) (M?=?Cr, Mo, W).