Vanadium Catalyst for C- and S-Alkylation of Benzhydrols in Water: An Experimental Study and Green Metrics Evaluation

A strategy for the vanadium-catalyzed dehydrative C- and S-alkylation by nucleophilic substitution of benzhydrols with arenes and thiols is reported. The alkylation was achieved with the divanadium oxoperoxo complex [K₃(V⁺⁵)₂(O₂²⁻⁾₄(O²⁻)₂(μ-OH)] in water under air. The newly developed transformation could accommodate a broad substrate scope, including (hetero)arenes and thiols (34 examples). Both the symmetrical and unsymmetrical benzhydrols furnished excellent yields of the alkylated product under mild reaction conditions. The scope of this strategy was further extended to synthesize bis-benzylated arenes (poly-arylated products) in high yields and regioselectivities. The green metrics determination of all the alkylated products suggests the technical and environmental benefits of the present protocol. The longevity experiment reveals the catalytic activity was maintained over seven cycles. To understand the mechanism of the present reaction, spectroscopic and kinetic studies were undertaken. This simple protocol, which affords the desired products with water as the by-product, can be achieved under mild conditions without needing a base or other additives.     

Defining the Determinant-like Function for m by n Matrices Using the Exterior Algebra

In this paper, we present a function called the Determinant-Like Function that generalises the determinant function to m by n matrices using the Clifford algebra C?(V, 0). By definition, this generalisation satisfies the property that the exterior product of its column vectors has a magnitude that equals its determinant-like function if it has more rows than columns. For matrices which have more columns than rows, we make use of another property that the exterior product of its rows has a magnitude that equals the absolute value of its determinant-like function if it has more columns than rows. Defining the sign of this determinant-like function remains an open question.     

On the Determinant-like Function and the Vector Determinant

A generalisation of the determinant to rectangular matrices, known as the determinant-like function, has its magnitude defined previously. In this paper, we show that the determinant-like function is a rotation of the vector determinant.We further propose that this rotation is an identity transformation and thus the determinant-like function is in fact the same as the vector determinant. From this, we derive some properties of the determinant-like function.     

Synthesis of C1–C11 eribulin fragment and its diastereomeric analogues

A practical stereoselective synthesis of the central C1–C10 fragment of eribulin and its two diastereomeric analogues is developed. Our approach relied on the use of l-ascorbic acid as the starting material which allowed accessing a key intermediate with a syn diol moiety (C9 and C10 of eribulin) and a carboxylic ester group. A functionalized six membered lactone having several required hydroxyl groups was then obtained. In a number of steps, the lactone was converted to an intermediate for our key oxa-Michael reaction. A regio- and stereocontrolled intramolecular oxa-Michael reaction completed the synthesis of the C1–11 fragment having a trans-fused tetrahydropyrans with the exact stereochemistry of various hydroxyl groups, as in eribulin.     

Photochemical activity of membrane-localised polyketide derived marine natural products

Marine organisms rely upon complex bio-chemical systems to manage photo-induced oxidative damage as part of a sophisticated chemical defense. Using a combination of synthetic chemistry and biophysical techniques, we provide evidence to support the notion that marine derived polyene γ-pyrone metabolites of sacoglossan molluscs become localised at cell membranes where they influence the total absorption of the harmful radiation by the lipid membrane, thereby functioning as sunscreen agents. We also report two new hyperperoxide analogues of the putative polyene biosynthetic precursors that themselves are likely candidate natural products.     

Microwave-assisted synthesis,characterization, and antimicrobial activity of some odorant Schiff bases derived from naturally occurring carbonyl compounds and anthranilic acid

Nine odorant Schiff bases, namely 2-(4-methoxybenzylideneamino) benzoic acid, 2-(benzylideneamino) benzoic acid, 2-(3-phenylallylidene amino) benzoic acid, 2-(3,7-dimethyloct-2,6-enylideneamino) benzoic acid, 2-(3,7-dimethyloct-6-enylideneamino) benzoic acid, 2-(4-isopropylbenzylideneamino)benzoic acid, 2-(3,4-dimethoxybenzylideneamino) benzoic acid, 2-(1-phenylethylideneamino) benzoic acid, and 2-[(4-(2,6,6-trimethylcyclohex-2-enyl)-but-2-enylideneamino)benzoic acid, were prepared by condensation of anthranilic acid with corresponding naturally occurring carbonyl compounds (anisaldehyde, benzaldehyde, cinnamaldehyde, citral, citronellal, cuminaldehyde, veratraldehyde, acetophenone, and α-ionone) employing conventional and microwave irradiation methods. These compounds were characterized with the aid of elemental and spectral (FT-IR, ¹H NMR, and ¹³C NMR) analysis. Microwave irradiation method was efficient in terms of reduced reaction time, solvent use, and increased yields of these compounds without affecting their olfactory characteristics. These Schiff bases also exhibited olfactory characteristics for various fragrance compositions and varied antimicrobial activity against Aspergillus niger, Penicillium chrysogenum, Staphylococcus aureus, and Escherichia coli.     

A model for compression dependence of thermal expansivity

In the present study, we propose a suitable model to compute volume dependence of thermal expansivity which is applicable up to infinite pressure or compression. The newly developed model satisfies the constraints of infinite pressure as suggested by high-pressure thermodynamics. The compression dependence of thermal expansivity for lower mantle of the Earth is evaluated with the help of the proposed model. A close agreement between theory and the results predicted with the seismic data is found, which in turn reveals the validity of the present work.     

Cyclononitols: a flexible synthetic approach towards nine-membered carbasugar analogues

A novel, concise, stereocontrolled approach to nine-membered carbasugar analogues (cyclononitols) from a bicyclo[4.3.1]deca-2,4-dien-10-one scaffold, harbouring a ‘locked’ cyclononane ring and latent functionalities, is described.     

An In Silico investigation for acyclovir and its derivatives to fight the COVID-19: Molecular docking,DFT calculations,ADME and td-Molecular dynamics simulations

In the present work, we have designed three molecules, acyclovir (A), ganciclovir (G) and derivative of hydroxymethyl derivative of ganciclovir (CH₂OH of G, that is D) and investigated their biological potential against the Mpro of nCoV via in silico studies. Further, density functional theory (DFT) calculations of A, G and D were performed using Gaussian 16 on applying B3LYP under default condition to collect the information for the delocalization of electron density in their optimized geometry. Authors have also calculated various energies including free energy of A, G and D in Hartree per particle. It can be seen that D has the least free energy. As mentioned, the molecular docking of the A, G and D against the Mpro of nCoV was performed using iGemdock, an acceptable computational tool and the interaction has been studied in the form of physical data, that is, binding energy for A, G and D were calculated in kcal/mol. It can be seen the D showed effective binding, that is, maximum inhibition that A and G. For a better understanding for the inhibition of the Mpro of nCoV by A, G and D, temperature dependent molecular dynamics simulations were performed. Different trajectories like RMSD, RMSF, Rg and hydrogen bond were extracted and analyzed. The results of molecular docking of A, G and D corroborate with the td-MD simulations and hypothesized that D could be a promising candidate to inhibit the activity of Mpro of nCoV.     

A new chromogenic spray reagent for the detection and identification of oxyfluorfen herbicide in biological material by high-performance thin-layer chromatography

JPC – Journal of Planar Chromatography – Modern TLC -