Unsymmetric 1,3,4-oxa(thia)diazoles of quinoxaline–naphthalene conjugates

Two new series of unsymmetric 1,3,4-oxa(thia)diazoles 1a,b containing both quinoxaline and naphthalene moieties were prepared and their mesomorphic properties were investigated. The mesomorphic behavior of compounds 1a,b and 2 was studied by DSC analysis and polarized optical microscopy. All compounds 1a and 2 exhibited hexagonal columnar phases (Col_h), which were also confirmed by powder XRD diffractometer. N_cell and R_ar values equal to 5.23 and 22.73 Å² within a slice of 9.0 Å thick were also obtained for 1a (n=16), indicating that a more disc-like structure constructed by two molecules lying side-by-side was correlated in Col_h phases. In contrast, all compounds 1b were not mesogenic, and the lack of mesomorphic properties in 1b might be due to their unfavorable conformations. The PL spectra of all compounds 1a,b showed one intense peak at λ_max=509–512 nm, and these photoluminescent emissions originated from quinoxaline moiety.     

Synthesis and hydrazinolysis of β-(1,3,4-oxadiazol-2-yl)pyridines

Cyclization of the hydrazide of 5-ethoxycarbonyl-2,6-dimethylpyridine-3-carboxylic acid by acylation with aromatic or aliphatic acid chlorides with subsequent boiling in POCl₃ or heating in orthoformic acid gave the corresponding ethyl 2,6-dimethyl-5-(5-R-1,3,4-oxadiazol-2-yl)pyridine-3-carboxylate. The cyclization of the reaction products with hydrazine hydrate has been studied. Cyclization of the dihydrazide of 2,6-dimethyl-3,5-pyridinedicarboxylic acid under analogous conditions gave only 3,5-bis-(5-R-1,3,4-oxadiazol-2-yl)-2,6-dimethylpyridines, containing R = 2-FC₆H₄, H.     

Reactions of α-mercaptocarboxylic acid hydrazides with triethyl orthoesters: synthesis of 1,3,4-thiadiazin-5(6H)-ones and 1,3,4-oxadiazoles

Reactions of α-mercapto-β-phenylpropionic and α-mercaptophenylacetic acid hydrazides with triethyl orthoesters were conducted under N₂ in glacial acetic acid and resulted in the formation of two groups of products, derivatives of 1,3,4-thiadiazin-5(6H)-ones and 2-(1-mercaptomethyl)-1,3,4-oxadiazoles. When conducting the same transformations on α-mercaptophenylacetic acid hydrazide in the presence of air, two different products from the 1,3,4-oxadiazole family, the appropriate bis(1,3,4-oxadiazol-2-yl-phenylmethyl) disulfides and 2-benzyl-1,3,4-oxadiazoles, were formed with the liberation of free sulfur. The oxygenated bis(1,3,4-oxadiazol-2-yl-phenylmethyl) disulfides were reduced to the corresponding 2-(1-mercaptomethyl)-1,3,4-oxadiazoles with the use of zinc powder under mild conditions.     

The total synthesis of (±)-myo-inositol-1,3,4-trisphosphate, (±)-myo-inositol-2,4,5-trisphosphate and (±)-myo-inositol-1,3,4,5-tetrakisphosphate

A total synthesis of (±)-myo-Inositol-1,3,4-Trisphosphate, (±)-myo-Inositol-2,4,5-Trisphosphate and (±)-myo-Inositol-1,3,4,5-Tetrakisphosphate is described.     

Adsorption of Uranium (VI) Ions on Hydrazinyl Amine and 1,3,4-Thiadiazol-2(3 H)-thion Chelating Resins

Nitrogenous compounds are the most widely used in solid phase extraction due to its low cost, easy convertible to many functional groups. These have large adsorptive capacity toward heavy metal ions as rare earth elements (REEs) and uranium with ability for recovering from low concentrate solutions. Synthesis of resins were carried out by polymerization of acrylonitrile with divinyl benzene as crosslinker. Treatment of the resulted precipitate with hydrazine hydrate in ethanol produce hydrazinyl methyl amine which has high chelating capacity toward uranyl ions. 1,3,4-Thiadiazol-2(3H)-thion derivative was yielded by reaction of hydrazinyl amine with carbon disulfide in methanol. This reaction carried out in the presence of methyl benzoate and dioctyl phthalate as pore producing solvent which used to improve physical properties and adsorptive character of the resins. Optimization on the two resins during loading and elution were carried out using solution with different concentrations. The optimum factors during adsorption and elution were recognized.     

Synthesis of N-Aryl-N′- (5-aryloxymethyl-1,3,4-thiadiazol-2-yl) ureas under Microwave Irradiation

The rapid heating effect of microwave irradiation has caught the attention of synthetic chemists in the recent times due to the remarkable reduction of reaction time. It is an efficient method because of its virtue of rapid heating capability, high yield and simple procedure. The superiority of these virtues goes beyond of traditional heating reaction.     

New diformazanes obtained from dihydrazides of S,S′-(1,3,4-thiadiazol-2,5-diyl)-bis(mercaptoacetic) or-(2-mercaptopropionic) acids

Hetaryldiformazanes have been prepared for the first time as the result of autooxidation of dihydrazones formed in the reaction of bis(arylhydrazones) of S,S-(1,3,4-thiadiazol-2,5-diyl)bis(mercaptoacetic) or-(2-mercaptopropionic) acid with 2-hydrazinobenzothiazole. Some structural characteristics of these diformazanes were confirmed by IR and H NMR spectroscopy.Institute of Chemistry, Vilnius LT-2600, Lithuania; e-mail: lorka@ktl.mii.lt. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, 547–550, April, 2000.     

Synthesis of 3-Substituted-6-(2,4-Dichlorophenyl)-s-Triazolo[3.4-b]-1,3,4-Oxadiazoles

2,5-DisubstitUted-l,3,4-oxadiazolederivativeshavebeenrePort6dtoshowantidrigal1,antiin-flamrnatoof,andplantgrowthpromoter3activities-3,4-Disubstituted-l,2,4-triazolecompoundsalsopossessantifimgal',andplantgrowthpromote/achvities.Authors6havereportedthat(3-bmpl4-aroyl-l,2,4-triazole-5-yl)[5-(3,4,5-triInethoxylphenyl>l,3,4roxadiazole-2-yl]sulfidesshowedsomeantifungalactivity.lnordertoscreennewcompoundsofpossessingphysiologicalactivity'andstUdythereactionruleofnucleophilicdisplacementwehavedevelo…     

Synthesis of benzazoles, 1,3,4-oxadiazoles,and 1,3,4-thiadiazoles containingβ-alkylthioethyl radicals

By the condensation of hydrochlorides of iminoesters of-alkylthiopropionic acids with o phenylenediamine, o-aminophenols, hydrazides of acids, and thiosemicarbazide, we have synthesized 2-substituted benzimidazoles and benzoxazoles, 2, 5-disubstituted 1, 3, 4-oxadiazoles, and 2-amino-5-substituted 1, 3, 4-thiadiazoles containing-alkylthiioethyl fragments.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 115–118, January, 1994.     

Copper-catalyzed direct cross coupling of 1,3,4-oxadiazoles with trans-β-halostyrenes: synthesis of 2-E-vinyl 1,3,4-oxadiazoles

The first direct C–H alkenylation of 1,3,4-oxadiazoles with trans-β-halo olefinic system has been carried out using a combination of CuI/DMEDA as a catalyst. A wide range of 2-E-vinyl-substituted oxadiazoles were obtained in high yields (85–93%).     

One-pot method for the synthesis of sulfonated poly(1,3,4-oxadiazoles) based on 4,4’-oxydibenzoic acid

A series of new copolymers of poly(1,3,4-oxadiazole) that contain side protogenic sulfo groups are synthesized by the direct copolycondensation of terephthalic and 4,4’-oxydibenzoic acids and hydrazine sulfate in oleum. Variation in the polycondensation conditions makes it possible to synthesize copolymers containing phenylene moieties with either 4-sulfo-10,10-dioxophenoxatiine or 4,4’-oxybis(3-sulfophenyl) moieties or a combination of the three moieties. This approach permits easy control over the physicochemical properties of the copolymers and the amount of protogenic sulfo groups. It is shown that the introduction of sulfonated moieties into copolymer molecules makes it possible to obtain materials with high values of ionexchange capacity (1.5 mmol/g) and water absorption (110%), while the strength and thermal stability inherent in poly(p-phenylene 1,3,4-oxadiazoles) remain intact.     

Application of Sulfinyl bis(2,4‐dihydroxythiobenzoyl) in the Synthesis of N‐Substituted 2‐Amino‐5‐(2,4‐dihydroxyphenyl)‐1,3,4‐thiadiazoles

One‐stage synthesis of N‐substituted 2‐amino‐5‐(2,4‐dihydroxyphenyl)‐1,3,4‐thiadiazoles is described. The compounds were prepared by the reaction of the sulfinyl bis(2,4‐dihydroxythiobenzoyl) (STB) with 4‐substituted 3‐thiosemicarbazides. STB was obtained from 2,4‐dihydroxybenzenecarbodithioic acid and thionyl dichloride. The structure of compounds was confirmed by IR, ¹H NMR, ¹³C NMR, and EI‐MS data.     

Photoluminescence and Electroluminescence Properties of 2,5-Bis[2,2′-bis(5-phenyl)-1,3,4-oxadiazole] Thiophene(T-OXD)and T-OXD/Poly(9-vinylcarbazole) Blends

The photoluminescence(PL) and the electroluminescence(EL) properties of a novel organic compound, 2,5-bis(2,2′-bis(5-phenyl)-1,3,4-oxadiazole(T-OXD), were studied in chloroform and in a solid thin film. The PL and the EL properties of T-OXD/poly(9-vinylcarbazole)(PVK) blends were also studied, which contained various contents of T-OXD. The PL maximum emission peaks of T-OXD/PVK blends show gradual bathochromtic-shift with the increase of the T-OXD content. The EL spectra of T-OXD/PVK devices are similar to their PL spectra, and all the EL maximum emission peaks show bathochromtic-shift compared with the corresponding PL spectra, which is ascribed to the formation of electroplex. The turn-on voltages for ITO/T-OXD:PVK/Al devices decreased from 13.5 V of the device cotaining 0.1% T-OXD(mass fraction) to 5 V of the device containing 5% T-OXD, which suggests that T-OXD improves the energy level match between T-OXD and PVK and enhances the emission efficiency. The experimental results indicate that T-OXD can be used as a good electron transporting material.     

Synthesis and Characterization of New Thebaine Derivatives: 2-(6,14-endo-Ethenotetrahydrothebaine-7α;-yl)-5-(N-Arylamino)-1,3,4-Thiadiazoles

Abstract

We have synthesized a series of novel 2-(6,14-endo-ethenotetrahydrothebaine-7α-yl)-5-N-arylamino-1,3,4-thiadiazoles (5a–n) as potential narcotic analgesics, which are analogs of morphine. The synthesized compounds exhibit rigid morphine structures, including a 6,14-endo-entheno bridge and a 5-N-arylamino-1,3,4-thiadiazol-2-yl group at C-7 position that adopted S-configuration. The structures and stereochemistry of the compounds were completely assigned using one- and two-dimensional NMR experiments (¹H NMR, APT, COSY, NOESY, HMQC, and HMBC), FTIR, and high-resolution mass spectral (HRMS) data.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Cyclocondensation of 2-Amino-1,3,4-thiadiazoles with β-Sulfonylvinyltrifluoromethyldiols

A series of CF₃-containing 6,7-dihydro-5H-[1,3,4]thiadiazolo[3,2-a]pyrimidin-7-ols was obtained by the interaction of 2-amino-1,3,4-thiadiazoles with -sulfonylvinyltrifluoromethyldiols and their stereochemistry was established. The structure of 5-(phenylsulfonyl)-7-(trifluoromethyl)-6,7-dihydro-5H-[1,3,4]thiadiazolo[3,2-a]pyrimidin-7-ol was confirmed by X-ray crystallography.     

Synthesis of 1,4‐Bis[(3‐Aryl)‐s‐triazolo(3,4‐b)‐(1,3,4)thiadiazole‐6‐yl]benzenes

Some 1,4‐bis[(3‐aryl)‐s‐triazolo[3,4‐b]‐[1,3,4]thiadiazole‐6‐yl]benzenes are readily accessible in high yields by reaction of 3‐aryl 4‐amino‐5‐mercapto‐1,2,4‐triazole with p‐phthalic acid.     

Synthesis and Crystal Structure of 1-D Chain Copper(Ⅱ) Complex:[Cu(L)Cl2]n(L = 2,5-Di-2-pyridyl-1,3,4-oxodiazole)

The title complex, [Cu(L)Cl2]n (L = 2,5-di-2-pyridyl-1,3,4-oxodiazole) 1, has mixture solvent of CH3CN and CH2Cl2 (L is generated from the metal-assisted hydrolysis reaction of bptz) and structurally characterized. It crystallizes in space group C2/c of monoclinic system with cell parameters: a = 9.812(2), b = 12.679(3), c = 1 1.111(2) A, β = 103.92(3)°, V = 1341.6(5)A3, Z = 4, Dc = 1.776 g/cm3, Mr= 358.66, F(000) = 716, μ = 2.024 mm-1 and S = 1.004. The final R = 0.0346 and wR = 0.0938 for 1011 observed reflections with I ＞ 2σ(I). The Cu( Ⅱ ) ion is six-coordinated by four N atoms of two L ligands and two Cl- ions in a distorted octahedral geometry. The ligand L acts as a bis-bidentate ligand to bridge the Cu( Ⅱ ) ions, resulting in an infinite chain structure.     

Synthesis and antiviral activity of 5‑(4‑chlorophenyl)-1,3,4-thiadiazole sulfonamides

Starting from 4-chlorobenzoic acid, 10 new 5-(4-chlorophenyl)-N-substituted-N-1,3,4-thiadiazole-2-sulfonamide derivatives were synthesized in six-steps. Esterification of 4-chlorobenzoic acid with methanol and subsequent hydrazination, salt formation and cyclization afforded 5-(4-chlorophen-yl)-1,3,4-thiadiazole-2-thiol (5). Conversion of this intermediate into sulfonyl chloride 6, followed by nucleophilic attack of the amines gave the title sulfonamides 7a-7j whose structures were confirmed by NMR, IR and elemental analysis. The bioassay tests showed that compounds 7b and 7i possessed certain anti-tobacco mosaic virus activity.     

2,5-二(对硝基苯基)-1,3,4-噻二唑的合成

通过对硝基苯甲酰氯与肼反应合成了对硝基苯甲二酰肼，后者与P2S5缩合反应合成了2，5－二对硝基苯基－1，3，4－噻二唑。研究了合成反应条件，使用吡啶作溶剂，收率76．2％。经元素分析，IR，^1H NMR和MS确证了产物的结构。生物活性初步研究表明，该化合物具有一定的杀菌活性。     

Syntheses and Crystal Structures of Two Novel Cobalt(Ⅱ) Complexes with 2-Amino-5-substituted-1,3,4-thiadiazole as Ligands

Two novel cobalt(Ⅱ) compounds were obtained and characterized by X-ray single-crystal diffraction,IR,1H NMR and elemental analysis.Compound 1 crystallizes in monoclinic,space group P21/n,with a = 18.046(4),b = 11.335(3),c = 19.157(5) ,β = 92.707(3)o,Z = 4,V = 3914.4(16) 3,Mr = 968.56,Dc = 1.644 g/cm3,μ = 1.378 mm-1,F(000) = 1960,the final R = 0.0367 and wR = 0.0895.The crystal of compound 2 is of monoclinic,space group P21/c with a = 8.7253(10),b = 10.9031(13),c = 18.235(2) ,β = 93.2210(10)o,Z = 4,V = 1732.0(3) 3,Mr = 464.21,Dc = 1.780 g/cm3,μ = 1.560 mm-1,F(000) = 932,the final R = 0.0322 and wR = 0.0743.