Iodine-promoted one-pot synthesis of 1,3,4-oxadiazole scaffolds <i>via</i> sp<sup>3</sup> C–H functionalization of azaarenes

Mani, Ganesh Kumar; Donthiboina, Kavitha; Shankaraiah, Nagula; Kamal, Ähmed

doi:10.1039/c9nj03573g

Cited by 13 publications

(20 citation statements)

References 79 publications

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“…Preparation of ligand 2-(furan-2-yl)-5-(pyridin-2-yl)-1,3,4-oxadiazole (fpo) is already described in the literature [30]. However, we obtained fpo through a four-step reaction, which shows simplified reaction Scheme 2.…”

Section: Synthesismentioning

confidence: 99%

The Structural and Magnetic Properties of FeII and CoII Complexes with 2-(furan-2-yl)-5-pyridin-2-yl-1,3,4-oxadiazole

et al. 2020

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Two novel coordination compounds containing heterocyclic bidentate N,N-donor ligand 2-(furan-2-yl)-5-(pyridin-2-yl)-1,3,4-oxadiazole (fpo) were synthesized. A general formula for compounds originating from perchlorates of iron, cobalt, and fpo can be written as: [M(fpo)2(H2O)2](ClO4)2 (M = Fe(II) for (1) Co(II) for (2)). The characterization of compounds was performed by general physico-chemical methods—elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) in case of organics, and single crystal X-ray diffraction (sXRD). Moreover, magneto-chemical properties were studied employing measurements in static field (DC) for 1 and X-band EPR (Electron paramagnetic resonance), direct current (DC), and alternating current (AC) magnetic measurements in case of 2. The analysis of DC magnetic properties revealed a high spin arrangement in 1, significant rhombicity for both complexes, and large magnetic anisotropy in 2 (D = −21.2 cm−1). Moreover, 2 showed field-induced slow relaxation of the magnetization (Ueff = 65.3 K). EPR spectroscopy and ab initio calculations (CASSCF/NEVPT2) confirmed the presence of easy axis anisotropy and the importance of the second coordination sphere.

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Section: Synthesismentioning

confidence: 99%

The Structural and Magnetic Properties of FeII and CoII Complexes with 2-(furan-2-yl)-5-pyridin-2-yl-1,3,4-oxadiazole

et al. 2020

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“…Infrared spectral data were acquired from the (form) listed. All 1 H and 13 C NMR data were acquired from a 500 MHz or 800 MHz multinuclear spectrometer with a broad-band N 2 cryoprobe. Chemical shifts are reported using the δ scale and are referenced to the residual solvent signal: CDCl 3 (δ 7.26), CD 2 Cl 2 Scheme 3.…”

Section: ■ Conclusionmentioning

confidence: 99%

“…Reported yields are for spectroscopically pure material isolated postreaction, four successive steps from the requisite carbaldehyde, or from automated flash column chromatography, where appropriate, as confirmed by 1 H NMR spectroscopy. (5.32), (CD 3 ) 2 C�O (2.05), and (CD 3 ) 2 S�O (2.50) for 1 H NMR and CDCl 3 (δ 77.15), CD 2 Cl2 (53.82), and (CD 3 ) 2 C�O (29.84), and (CD 3 ) 2 S�O (39.52) for 13 C NMR. 25 Splittings are reported as follows: (br) = broad, (s) = singlet, (d) = doublet, (t) = triplet, (dd) = doublet of doublets, (dt) = doublet of triplets, (ddd) doublet of doublet of doublets, and (m) = multiplet.…”

Section: ■ Conclusionmentioning

confidence: 99%

“…In 2013, Chang and co-workers reported an oxidative annulation of aryl carbaldehydes with alkyl- and benzohydrazides with two heteroaryl carbaldehyde examples . Contemporary strategies combining methyl-heteroarene oxidation and subsequent 1,3,4-oxadiazole formation via independent disclosures by Kamal and Zhu have also been reported . Huang has published the utility of sp 2 - and sp -functionalized arenes for cyclization with benzohydrazides .…”

Section: Introductionmentioning

confidence: 99%

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Synthetic Access to Unsymmetric, Tridentate, Pyridyl-1,3,4-oxadiazole Complexants via Intramolecular Oxidative Annulation of Arylhydrazides with Heteroaryl Carbaldehydes

Dzeagu

Carrick

2022

J. Org. Chem.

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Over the last four decades, an ideal complexant for the chemoselective liquid−liquid separation of the minor actinides from the lanthanides contained within spent nuclear fuel has yet to be realized. As strategic performance objectives continue to evolve as a function of time, solubility in process-relevant diluents, fast complexation kinetics, as well as robustness to hydro-and radiolytic degradation remain at the forefront of this grand challenge. While the vast majority of soft-N-donors are symmetric in nature, this laboratory has focused on defining synthetic methods to afford unsymmetric complexants for further study to explore the impact subtle changes to the molecular topography of the complexant moiety have on performance, in addition to working toward the definition of structure−activity relationships. The development of an intramolecular iodine-mediated oxidative annulation of heteroaryl-aryl-hydrazones for the production of functionalized, tridentate, and unsymmetric 1,3,4-oxadiazole-based complexants is reported. Optimization of reaction conditions afforded numerous products in high isolated yield over two linear steps in one pot in one hour of reaction time. The cleanliness of the optimized conditions negated the need for the chromatographic purification of 32 of 44 examples attempted. Method development, optimization, substrate scope, application to related heteroarenes, and a scale-up reaction are described herein.

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“…Recently, alternative approaches to the construction of aryl-1,2,3-triazoles without the use of azides have been disclosed (Figure ). Given the ubiquity of diversely-functionalized acetophenones, in concert with ease of conversion to the subsequent N-tosylhydrazone by condensation, method development toward this goal for the production of 1,2,3-triazoles on the current scaffolds of interest appeared prudent. Pursuant to the aforementioned, we report an efficient, regioselective, metal- and azide-free synthesis of diversified pyridyl-1,2,3-triazoles, and related heteroaryls, from N-tosyl hydrazones and anilines in only 0.2 h facilitated by microwave irradiation.…”

Section: Introductionmentioning

confidence: 99%

Microwave-Assisted, Metal- and Azide-Free Synthesis of Functionalized Heteroaryl-1,2,3-triazoles via Oxidative Cyclization of N-Tosylhydrazones and Anilines

et al. 2022

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As the search for competent soft-Lewis basic complexants for separations continues to evolve toward identification of a chemoselective moiety for speciation of the minor actinides from the electronically similar lanthanides, synthetic methods must congruently evolve. Synthetic options to convergently construct unsymmetric heteroaryl donor complexants incorporating a 1,2,3-triazole from accessible starting materials for evaluation in separation assays necessitated the development of the described methodology. In this report, metal- and azide-free synthesis of diversely functionalized pyridyl-1,2,3-triazole derivatives facilitated by microwave irradiation was leveraged to prepare a novel class of tridentate ligands. The described work negates the incorporation of thermally sensitive and toxic organoazides by using N-tosylhydrazones and anilines as viable synthetic equivalents in an efficient 12 min reaction time. Adaptation to alternative synthons useful for drug discovery was also realized. Method discovery, optimization, N-tosylhydrazone and aniline substrate scope, as well as a preliminary mechanistic hypotheses supported by DFT calculations are reported herein.

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Iodine-promoted one-pot synthesis of 1,3,4-oxadiazole scaffolds via sp³ C–H functionalization of azaarenes

Abstract: An efficient metal-free one-pot protocol has been developed for the construction of 1,3,4-oxadiazole derivatives via iodine-mediated oxidative amination of benzylic C–H bonds of azaarenes.

Cited by 13 publications

References 79 publications

The Structural and Magnetic Properties of FeII and CoII Complexes with 2-(furan-2-yl)-5-pyridin-2-yl-1,3,4-oxadiazole

The Structural and Magnetic Properties of FeII and CoII Complexes with 2-(furan-2-yl)-5-pyridin-2-yl-1,3,4-oxadiazole

Synthetic Access to Unsymmetric, Tridentate, Pyridyl-1,3,4-oxadiazole Complexants via Intramolecular Oxidative Annulation of Arylhydrazides with Heteroaryl Carbaldehydes

Microwave-Assisted, Metal- and Azide-Free Synthesis of Functionalized Heteroaryl-1,2,3-triazoles via Oxidative Cyclization of N-Tosylhydrazones and Anilines

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Iodine-promoted one-pot synthesis of 1,3,4-oxadiazole scaffolds via sp3 C–H functionalization of azaarenes

Abstract: An efficient metal-free one-pot protocol has been developed for the construction of 1,3,4-oxadiazole derivatives via iodine-mediated oxidative amination of benzylic C–H bonds of azaarenes.

Cited by 13 publications

References 79 publications

The Structural and Magnetic Properties of FeII and CoII Complexes with 2-(furan-2-yl)-5-pyridin-2-yl-1,3,4-oxadiazole

The Structural and Magnetic Properties of FeII and CoII Complexes with 2-(furan-2-yl)-5-pyridin-2-yl-1,3,4-oxadiazole

Synthetic Access to Unsymmetric, Tridentate, Pyridyl-1,3,4-oxadiazole Complexants via Intramolecular Oxidative Annulation of Arylhydrazides with Heteroaryl Carbaldehydes

Microwave-Assisted, Metal- and Azide-Free Synthesis of Functionalized Heteroaryl-1,2,3-triazoles via Oxidative Cyclization of N-Tosylhydrazones and Anilines

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Iodine-promoted one-pot synthesis of 1,3,4-oxadiazole scaffolds via sp³ C–H functionalization of azaarenes