Mn(III) salen complexes-catalyzed enantioselective addition of trimethyl silylcyanide to N-benzylimines in the presence of 4-phenyl pyridine-N-oxide as an additive

Chiral monomeric and dimeric Mn(III) salen complexes viz., [(S,S)-N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminato manganese(III) chloride and 5,5-methylene di-[(S,S)-{N-(3-tert-butyl salicylidine)-N′-(3′,5′-di-tert-butyl salicylidene)}-1,2-cyclohexanediaminato manganese(III) chloride were used as catalysts for the highly enantioselective Strecker reaction of various imines (derived by the condensation of aldehydes and amine) with TMSCN as a source of cyanide in toluene. Excellent yield (95%) of α-amino nitrile with ee >99% was achieved when N-(2-methoxybenzylidine)-1-phenylmethanamine was used as a substrate and 4-phenyl pyridine-N-oxide (4-PPNO) as an additive at ?55 °C in 28 h. The dimeric catalyst was found to be more reactive and enantioselective than the monomeric catalyst. The chiral dimeric catalyst used in the present study was recoverable and recyclable several times with retention of its performance.     

Phosphonate-Modified UiO-66 Brønsted Acid Catalyst and Its Use in Dehydra-Decyclization of 2-Methyltetrahydrofuran to Pentadienes

Phosphorus-modified all-silica zeolites exhibit activity and selectivity in certain Brønsted acid catalyzed reactions for biomass conversion. In an effort to achieve similar performance with catalysts having well-defined sites, we report the incorporation of Brønsted acidity to metal–organic frameworks with the UiO-66 topology, achieved by attaching phosphonic acid to the 1,4-benzenedicarboxylate ligand and using it to form UiO-66-PO₃H₂ by post-synthesis modification. Characterization reveals that UiO-66-PO₃H₂ retains stability similar to UiO-66, and exhibits weak Brønsted acidity, as demonstrated by titrations, alcohol dehydration, and dehydra-decyclization of 2-methyltetrahydrofuran (2-MTHF). For the later reaction, the reported catalyst exhibits site-time yields and selectivity approaching that of phosphoric acid on all-silica zeolites. Using solid-state NMR and deprotonation energy calculations, the chemical environments of P and the corresponding acidities are determined.     

Anticancer and antibacterial potential of Rhus punjabensis and CuO nanoparticles

Abstract

The present study reports ecofriendly synthesis of CuO nanoparticles (NPs) using an extract of Rhus punjabensis as a reducing agent. NPs structural and composition analysis are evaluated by X-rays diffraction (XRD), Fourier transform infrared, Energy dispersive spectroscopy, Scanning electron microscopy, Transmission electron microscopy, and Thermal analysis. The NPs have pure single phase monoclinic geometry with spherical structure and high stability toward heat and with average particle size of about 36.6 and 31.27?nm calculated by XRD and SEM, respectively. NPs are tested for antibacterial, protein kinase (PK) inhibition, SRB cytotoxic, and NF-κB activities. Antibacterial activity is observed against B. subtilis and E. coli. Significant PK and SRB cytotoxic activity is observed with some NF-κB inhibition. NPs IC₅₀ values against HL-60 and PC-3 prostate cancer cells are 1.82?±?1.22 and 19.25?±?1.55?μg/mL. The results encourage further studies for antibacterial and anticancer drug development of NPs using animal models.     

Chelating behaviour of new 12-membered Schiff base macrocycles containing pendant groups

Summary The free Schiff base macrocycles 1,4,7,10-tetraazacyclo-dodeca-5,6,11,12-tetraaminoacetic acid-4,6,10,12-tetraene (L¹), 1,4,7,10-tetraazacyclododeca-5,6,11,12-tetraamino-phenyl-4,6,10,12-tetraene (L²) and 1,4,7,10-tetraazacyclo-dodeca-5,6,11,12-tetraaminopyridyl-4,6,10,12-tetraene (L³) have been prepared by the reaction of oxamidediacetic acid, oxamidediphenyl and oxamidedipyridyl, respectively, with ethylenediamine. Their complexes with first row transition metal ions, of types [MLCl₂] and [MLCl₂]Cl, have also been prepared and characterized by physico-chemical and spectroscopic methods. The complexes of divalent metal ions are non-ionic while those of trivalent metal ions appear to be 11 electrolytes. An octahedral geometry is proposed for all the complexes.     

磺化水热碳催化乙酰丙酸酯化生成戊酮酸乙酯(英文)

The synthesis of carbon-based, heterogeneous sulphonic catalysts for the production of levulinate esters. Hydrothermal treatment at moderated temperatures was employed to generate highly functional carbonaceous materials, referred to as hydrothermal carbons (HTCs), from both glucose, cellulose and rye straw. The products were sulfonated to generate solid acid-catalysts. Characterisation of the as-synthesised materials as well as catalyst activity tests were performed. SEM images indicate the micrometre-sized particles present in both HTCs were largely unaffected by sulfonation, although cellulose-derived HTC displayed signs of inadequate hydrolysis. FT-IR spectroscopy and elemental analysis confirmed successful incorporation of sulphonic groups. 13C solid state NMR, in addition to TGA, elucidated the carbons’ structural composition and supported the common-ly-proposed hydrothermal carbonisation mechanism. Finally, the catalysts were tested via levulinic acid-ethanol esterification and gave high conversion and ester-selectivities ( 90%).     

Optimization of the numerical treatment of the Darcy–Forchheimer flow of Ree–Eyring fluid with chemical reaction by using artificial neural networks

In this study, Darcy Forchheimer flow paradigm, which is a useful paradigm in fields such as petroleum engineering where high flow velocity effects are common, has been analyzed with artificial intelligence approach. In this context, first of all, Darcy–Forchheimer flow of Ree–Eyring fluid along a permeable stretching surface with convective boundary conditions has been examined and heat and mass transfer mechanisms have been investigated by including the effect of chemical process, heat generation/absorption, and activation energy. Cattaneo–Christov heat flux model has been used to analyze heat transfer properties. Within the scope of optimizing Darcy–Forchheimer flow of Ree–Eyring fluid; three different artificial neural network models have been developed to predict Nusselt number, Sherwood number, and skin friction coefficient values. The developed artificial neural network model has been able to predict Nusselt number, Sherwood number, and skin friction coefficient values with high accuracy. The findings obtained as a result of the study showed that artificial neural networks are an ideal tool that can be used to model Darcy–Forchheimer Ree–Eyring fluid flow towards a permeable stretch layer with activation energy and a convective boundary condition.     

Isolation and In Silico Prediction of Potential Drug-like Compounds with a New Dimeric Prenylated Quinolone Alkaloid from Zanthoxylum rhetsa (Roxb.) Root Extracts Targeted against SARS-CoV-2 (Mpro)

A new dimeric prenylated quinolone alkaloid, named 2,11-didemethoxy-vepridimerine A, was isolated from the root bark of Zanthoxylum rhetsa, together with twelve known compounds. The structure of the new compound was elucidated on the basis of spectroscopic investigations (NMR and Mass). The interaction of the isolated compounds with the main protease of SARS-CoV-2 (Mpro) was evaluated using molecular docking followed by MD simulations. The result suggests that 2,11-didemethoxy-vepridimerine A, the new compound, has the highest negative binding affinity against the Mpro with a free energy of binding of −8.5 Kcal/mol, indicating interaction with the Mpro. This interaction was further validated by 100 ns MD simulation. This implies that the isolated new compound, which can be employed as a lead compound for an Mpro-targeting drug discovery program, may be able to block the action of Mpro.     

Highly regioselective synthesis of chiral diamines via a Buchwald–Hartwig amination from camphoric acid and their application in the Henry reaction

In this work the synthesis of new asymmetric diamine ligands from camphoric acid is described. The new diamines can be directly prepared in a regioselective arylation of the less hindered primary amine group of (+)‐cis‐1,2,2‐trimethylcyclopentane‐1,3‐diamine via a Buchwald–Hartwig amination in high yields. The resulting diamines incorporate a secondary and primary amine group and were successfully applied as ligands in a copper‐catalyzed Henry reaction. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis of Some Novel Phenyl Substituted Oxothiazolidin- 1’’,3’’,4’’-thiadiazolo-[3’,4’-b]thiazoline of 3β-Substituted Cholestane

Three title compounds 4a—4c have been synthesized by the cyclodehydration of 1’-benzylidine-4’-(3β-substituted-5α-cholestane-6-yl)thiosemicarbazones 2a—2c with thioglycolic acid followed by the treatment with cold conc. H2SO4 in dioxane. The compounds 2a—2c were prepared by condensation of 3β-substituted-5α-cholestan- 6-one-thiosemicarbazones 1a—1c with benzaldehyde. These thiosemicarbazones 1a—1c were obtained by the reaction of corresponding 3β-substituted-5α-cholestan-6-ones with thiosemicarbazide in the presence of few drops of conc. HCl in methanol. The structures of the products have been established on the basis of their elemental, analytical and spectral data.