725-12-2Relevant academic research and scientific papers
Characterization of a new non-centrosymmetric polymorph of diphenyl-1,3,4-oxadiazole
Franco, Olga,Reck, Günter,Orgzall, Ingo,Schulz, Burkhard W.,Schulz, Burkhard
, p. 219 - 230 (2003)
Diphenyl-1,3,4-oxadiazole (DPO) crystallization experiments from solutions clearly reveal the polymorphism of the substance. Besides the formerly known centrosymmetric monoclinic structure with space group P21/c (DPO I) a new monoclinic structure with the non-centrosymmetric space group Cc is found (DPO II): a = 2.4134(4) nm, b = 2.4099(3) nm, c = 1.2879(2) nm, β = 110.048(3)° and V = 7.0363(17) nm3. The asymmetric unit contains six independent molecules in a complex packing motif. A re-determination of the crystal structure of DPO I at room temperature gives lattice parameters a = 0.51885(6) nm, b = 1.8078(2) nm, β = 1.21435(14) nm, β = 93.193(3)°, and V = 1.1373(2) nm3. X-ray measurements at 363 K show a significant increase of the unit cell volume by 1.6%. Differences between both structures concerning morphology and characteristic Raman bands are outlined in detail. DSC investigations show an irreversible transition from DPO I to DPO II at 97°C. DPO II does not show any transition in the temperature range up to the melting point at 141°C. The non-centrosymmetric DPO II structure shows triboluminescence.
Pd/Cu-Catalyzed C-H/C-H Cross Coupling of (Hetero)Arenes with Azoles through Arylsulfonium Intermediates
Lin, Zeng-Hui,Tian, Ze-Yu,Zhang, Cheng-Pan
supporting information, p. 4400 - 4405 (2021/06/27)
A highly efficient method for the selective formal C-H/C-H cross-coupling of azoles and (hetero)arenes was established through arylsulfonium intermediates under transition-metal catalysis, which produced a variety of 2-(hetero)aryl azoles in good to excellent yields. Advantages of the reaction included mildness, a good functional group tolerance, a wide range of substrates, a high regio- and chemoselectivity, one-pot procedures, and the late-stage functionalization of complex molecules without the use of oxidants, offering a promising strategy for the transition-metal-catalyzed C-H arylation of azoles.
The preparation, characterization and catalytic activity of Ni NPs supported on porous alginate-g-poly(p-styrene sulfonamide-co-acrylamide)
Alavinia, Sedigheh,Ghorbani-Vaghei, Ramin
, p. 29728 - 29740 (2021/10/06)
Herein, we report the synthesis of nickel nanoparticles under mild conditions using porous alginate-g-poly(p-styrene sulfonamide-co-acrylamide) as a protecting/stabilizing agent and sodium borohydride as a reducing agent. The porous cross-linked polymeric support was preparedviacombining the use of sol-gel, nanocasting, and crosslinking techniques, in which thep-styrene sulfonamide monomer (PSSA) andN,N′-methylene-bis (acrylamide) (MBA) cross-linker underwent copolymerization on the surface of sodium alginate in the presence of a SiO2nanoparticle (NP) template (Alg-PSSA-co-ACA). The prepared catalyst (Alg-PSSA-co-ACA@Ni) showed high catalytic activity for the one-step synthesis of 1,3,4-oxadiazoles from the reaction of hydrazides and aryl iodides through isocyanide insertion/cyclization.
Catalytic application of electrochemically prepared nickel oxide nanoparticles to synthesize 2, 5–disubstituted-1,3,4–oxadiazoles
Dare, Sushama B.,Gaikwad, Suresh T.,Rajbhoj, Anjali S.,Sawant, Manisha R.
, p. 300 - 308 (2020/07/03)
The present work aims to synthesize 2,5–disubstituted-1,3,4–oxadiazoles using electrochemically prepared nanoparticles of nickel oxide as catalyst.The nanoparticles thus prepared using electrochemical syntheses are in appreciable yield.The tetrabutyl phosphonium bromide has been used for capping followed by UV, FTIR, XRD, SEM EDS andTEM SAED studies for the characterization. The 2,5-disubstituted-1,3,4-oxadiazoles were synthesized from substituted benzoic acids and their hydrazides in microwave synthesis system using prepared nanoparticles as a catalyst.
Sodium hypochlorite-mediated synthesis of 2,5-disubstituted 1,3,4-oxadiazoles from hydrazides and aldehydes
Paidi, Karuna Raman,Kolli, Murali Krishna,Reddy, Eeda Koti,Pedakotla, Venkata Ramana
, p. 371 - 376 (2020/05/04)
[Figure not available: see fulltext.] A simple and convenient method for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles has been developed. Structurally divergent symmetrical and unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles can be obtained in moderate to high yields via NaOCl-mediated oxidative cyclization of N-acylhydrazones, generated in situ from aliphatic and aromatic hydrazides and aldehydes.
Experimental and Theoretical Studies on the Mechanism of DDQ-Mediated Oxidative Cyclization of N-Aroylhydrazones
Baek, Jihye,Je, Eun-Kyung,Kim, Jina,Qi, Ai,Ahn, Kwang-Hyun,Kim, Yongho
, p. 9727 - 9736 (2020/10/02)
The controversial single-electron-transfer process, frequently proposed in many 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)-mediated reactions, was investigated experimentally and theoretically using the oxidative cyclization of aroylhydrazone with DDQ. DDQ-mediated oxadiazole formation involves several processes, including cyclization to form an oxadiazole ring and N-H bond cleavage, either by proton, hydride, or hydrogen atom transfer. The detailed mechanistic study using the M06-2X density functional theory, and the 6-31+G(d,p) basis set, suggests that the pathways involving radical ion pair (RIP) intermediates, which resulted from single-electron transfer (SET), were found to be energetically nearly identical to the pathway without the SET. The substituent-dependent reactivity of oxadiazole formation was consistent with the free energy profiles of both pathways, with or without the SET. This result indicates that in addition to the electron-transfer pathway, the nucleophilic addition/elimination pathway for DDQ should be considered as a possible mechanism of the oxidative transformation reaction using DDQ.
UV-Induced 1,3,4-Oxadiazole Formation from 5-Substituted Tetrazoles and Carboxylic Acids in Flow
Green, Luke,Livingstone, Keith,Bertrand, Sophie,Peace, Simon,Jamieson, Craig
supporting information, p. 14866 - 14870 (2020/11/11)
A range of 1,3,4-oxadiazoles have been synthesized using a UV-B activated flow approach starting from carboxylic acids and 5-substituted tetrazoles. The application of UV light represents an attractive alternative to the traditional thermolytic approach and has demonstrated comparable efficiency and versatility, with a diverse substrate scope, including the incorporation of highly substituted amino acids.
Electrochemical Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazoles from α-Keto Acids and Acylhydrazines Under Mild Conditions
Lu, Fangling,Gong, Fengping,Li, Liangsen,Zhang, Kan,Li, Zhen,Zhang, Xinwei,Yin, Ying,Wang, Ying,Gao, Ziwei,Zhang, Heng,Lei, Aiwen
supporting information, p. 3257 - 3260 (2020/05/25)
1,3,4-Oxadiazoles are a kind of useful heterocycles which can be frequently found in materials and bioactive molecules. In this study, intermolecular electrochemical cyclization between α-keto acids and acylhydrazines has been developed for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles with the yield up to 91 %. This transformation can be run under mild reaction conditions in the absence of external oxidant, base and transition metal catalyst. Both symmetrical and unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles could be prepared according to the careful choice of the substrate combination. Gram scale synthesis also illustrates the potential application of this protocol in large preparation.
Harnessing Autoxidation of Aldehydes: In Situ Iodoarene Catalyzed Synthesis of Substituted 1,3,4-Oxadiazole, in the Presence of Molecular Oxygen
Chauhan, Jyoti,Ravva, Mahesh K,Sen, Subhabrata
, p. 6562 - 6565 (2019/09/04)
Isobutyraldehyde underwent auto-oxidation in the presence of molecular oxygen to generate an acyloxy radical under a "metal-free" environment. They were subsequently exploited in situ to afford hypervalent iodines with p-anisolyl iodide which generated substituted 1,3,4-oxadiazoles in moderate to excellent yields from N′-arylidene acetohydrazides. The reaction strategy tolerated diverse substitution on the hydrazide substrates. Control experiments and literature precedence supported the formation of an in situ iodosylarene complex that facilitates the formation of products.
One pot solvent-free solid state synthesis, photophysical properties and crystal structure of substituted azole derivatives
Du, Yanting,Wan, Zilu,Chen, Lianqing,Wu, Lamei
, p. 315 - 325 (2019/05/27)
A solvent-free solid state method has been developed to synthesize three series of substituted azole derivatives (including 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole) in high yields by condensation cyclization of N,N′-bishydrazide derivatives with corresponding cyclization agents, respectively. This general method avoids the use of organic solvents, saves cost and resources, simplifies post-processing and increases reaction rates. These compounds have been fully characterized by 1H NMR, 13C NMR, elemental analysis and MS. The structure of 2,5-di (4-tertbutylphenyl)-1,3,4-oxadiazole has been determined by single crystal X-ray diffraction analysis. The cell parameters are as follows: monoclinic crystal system, Cc space group, a = 18.735 (2) ?, b = 6.3375 (8) ?, c = 16.824 (2) ? and α = γ = 90°; β = 98.292 (2). The electronic absorption and fluorescent properties of these compounds have been systematically investigated for the first time. The relationships between heterocyclic structures and photophysical properties have been discussed. The alteration of emission and absorption wavelengths can be elucidated by hybrid atoms' electronegativity and Substituents' Hammett constants. This approach proposes a novel insight to provide a great number of novel substituted azole derivatives with good photophysical properties by a general green method.
