Benzimidazole bearing Pd–PEPPSI complexes catalyzed direct C2-arylation/heteroarylation of N-substituted benzimidazoles

A convenient and highly efficient palladium-catalyzed direct C2-arylation/heteroarylation of N-substituted benzimidazole derivatives such as N-benzyl/3-chlorobenzyl/2,4,6-trimethylbenzyl/2,4,6-triisopropylbenzyl/aryl benzimidazoles with various aryl/heteroaryl bromides in the presence of Pd–PEPPSI (palladium-pyridine enhanced pre-catalyst preparation stabilization and initiation) complexes is reported. In order to that we have prepared a series of different symmetrical and unsymmetrical N,N′-diaralkyl benzimidazole-bearing Pd–PEPPSI complexes. Among all of the the prepared complexes, Pd–PEPPSI- 3 effectively tuned the reaction at a relatively higher rate under mild reaction conditions in an ethanol–water system. In addition, the catalytic process avoids the use of external ligand and additives. Further the reactivity was compared with commercially available copper-N-heterocyclic carbene catalyst, but the reaction was less successful. With the optimized reaction conditions, a wide range of 2-aryl/heteroaryl-N-substituted benzimidazoles were synthesized in good to excellent yields via Csp²-H/Csp²-X biaryl cross-coupling.     

Iodine mediated synthesis of some new imidazo[1,2-a]pyridine derivatives and evaluation of their antimicrobial activity

Herein, we reported a series of new 2-(5-methyl-1-aryl-1H-1,2,3-triazol-4-yl)imidazo[1,2-a]pyridines by using iodine and NH₄OAc in good yields. The structures of the titled compounds were characterized by the elemental analysis, ¹H NMR, ¹³C NMR, IR, and mass spectral analysis. All the titled compounds were screened for their in vitro antibacterial and antifungal activities by using streptomycin and Nystatin as standard drugs. The compounds 3k , 3l , 3g , and 3c exhibited potent activity against the tested bacterial strains and 3k , 3l , and 3c exhibited potent activity against the tested fungal strains than the reference drugs.     

A meglumine catalyst–based synthesis,molecular docking,and antioxidant studies of dihydropyrano[3, 2-b]chromenedione derivatives

A simple method was employed for the synthesis of dihydropyrano[3, 2-b]chromenedione derivatives ( 4a-o) in high yields by condensation of 5, 5-dimethylcyclohexane-1, 3-dione( 1 ), different aromatic aldehydes ( 2a-o ), and 5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one( 3 ), using meglumine as a stable and reusable catalyst. Meglumine, an amino sugar, was employed as an environmentally benign catalyst, due to its splendid properties such as being inexpensive, recyclable, and biodegradable. The accomplished protocol employs low catalyst loading and easy work-up for the synthesis of 5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one derivatives. A great asset is that without any significant loss, the catalyst could be recovered and reused for extended synthetic steps. This offer huge advantage to overcome recyclability issues. Our synthesized compounds were analyzed by IR, ¹H, ¹³C NMR, mass spectra and evaluated for their antioxidant properties by 1, 1-diphenyl-2-picryl hydrazyl radical (DPPH), hydrogen peroxide(H₂O₂), and nitric oxide (NO) scavenging methods. The correlation in exhibition of antioxidant activity was effective at all doses. The binding interactions and molecular docking studies for entitled compounds were studied against 3MNG protein; 4k exhibited marked binding affinity with excellent docking score of −7.6 Kcal/mol and emerged as a lead compound.     

An efficient microwave accelerated three component reaction of phenacyl azides and pyridinium phenacyl salts: A facile greener approach to 2-amino-2-ene-1,4-diones/pyrrolidin-2-ones

Abstract

A mild and efficient base promoted, microwave assisted, green synthesis of 2-amino-2-ene-1,4-diones has been described by the decomposition of phenacyl azides followed by treatment with pyridinium salts of phenacyl bromides in aqueous media. A diverse range of substrates bearing electron-releasing and electron-withdrawing substituents were well tolerated and delivered corresponding 2-amino-2-ene-1,4-diones in good yields. Synthesized 2-amino-2-ene-1,4-diones have been further explored in the synthesis of various substituted 4-hydroxypyrrolidin-2-ones.     

Difluoroacetaldehyde N-Triftosylhydrazone (DFHZ-Tfs) as a Bench-Stable Crystalline Diazo Surrogate for Diazoacetaldehyde and Difluorodiazoethane

Despite the growing importance of volatile functionalized diazoalkanes in organic synthesis, their safe generation and utilization remain a formidable challenge because of their difficult handling along with storage and security issues. In this study, we developed a bench-stable difluoroacetaldehyde N-triftosylhydrazone (DFHZ-Tfs) as an operationally safe diazo surrogate that can release in situ two low-molecular-weight diazoalkanes, diazoacetaldehyde (CHOCHN₂) or difluorodiazoethane (CF₂HCHN₂), in a controlled fashion under specific conditions. DFHZ-Tfs has been successfully employed in the Fe-catalyzed cyclopropanation and Doyle–Kirmse reactions, thus highlighting the synthetic utility of DFHZ-Tfs in the efficient construction of molecule frameworks containing CHO or CF₂H groups. Moreover, the reaction mechanism for the generation of CHOCHN₂ from CF₂HCHN₂ was elucidated by density functional theory (DFT) calculations.     

Substrate temperature influenced ZrO2 films for MOS devices

The effect of substrate temperature on the direct current magnetron-sputtered zirconium oxide (ZrO₂) dielectric films was investigated. Stoichiometric of the ZrO₂ thin films was obtained at an oxygen partial pressure of 4.0 × 10⁻² Pa. X-ray diffraction studies revealed that the crystallite size in the layer was increased from 4.8 to 16.1 nm with increase of substrate temperature from 303 to 673 K. Metal-oxide-semiconductor devices were fabricated on ZrO₂/Si stacks with Al gate electrode. The dielectric properties of ZrO₂ layer and interface quality at ZrO₂/Si were significantly influenced by the substrate temperature. The dielectric constant increased from 15 to 25, and the leakage current density decreased from 0.12 × 10⁻⁷ to 0.64 × 10⁻⁹ A cm⁻² with the increase of substrate temperature from 303 to 673 K.     

Synthesis of 5-{[(1-Aryl-1H-1,2,3-triazol-4-yl)methyl]sulfanyl}-1-phenyl-1H-tetrazoles

Russian Journal of Organic Chemistry - A series of novel 5-(1,2,3-triazolylmethylsulfanyl)tetrazole derivatives were synthesized by the click reaction from...     

Total Synthesis of Macrocyclic Dysoxylactam A

The total synthesis of dysoxylactam A, a novel 17‐membered macrolactam with potent multi‐drug‐resistant reversing activities, has been achieved, starting from 4‐pentene‐1‐al in a longest linear sequence of 17 steps and 9.5% overall yield. The key transformations consist of iterative aldol and ring‐closing metathesis reactions for the construction of the stereochemically enriched polypropionate scaffold and the macrocycle, respectively.     

Synthesis,Crystal Structure,and DNA Binding Studies of the 3-(2-(2-Hydroxybenzylidene)Hydrazinyl)Quinoxalin-2(1H)-One

Crystallography Reports - The Schiff base, 3-(2-(2-hydroxybenzylidene)hydrazinyl)quinoxalin-2(1H)-one has been synthesized by condensation of 3-hydrazinyl quinoxalin-2(1H)-one and salicylaldehyde...     

Microwave assisted synthesis of novel methylenebis{2-[(1-benzyl/cyclohexyl-1H-1,2,3-triazol-4-yl)methoxy]chalcones} and their antibacterial activity

A series of novel methylenebis{2-[(1-benzyl/cyclohexyl-1H-1,2,3-triazol-4-yl)methoxy]chalcones} (IVa-IVn) have been synthesized by the Click reaction and Claisen-Schmidt condensation of 5,5′-methylenebis[2-(prop-2-yn-1-yloxy)benzaldehyde] under microwave irradiation with high yields. All products have been characterized by spectral data including FT-IR, ¹H, and ¹³C NMR, mass spectrometry, and tested for their antibacterial activity.