Catalytic regioselective sulfonylation of alpha-chelatable alcohols: scope and mechanistic insight

This paper describes a convenient protocol for the regioselective sulfonylation of alpha-chelatable alcohols. Typically, the reaction of alpha-heterosubstituted alcohols with 1 equiv of p-TsCl and 1 equiv of Et(3)N in the presence of 2 mol % of Bu(2)SnO leads to rapid, regioselective, and exclusive monotosylation. The pK(a) of the amine was correlated to the reaction rate. A plausible mechanism for this reaction has been proposed on the basis of (119)Sn NMR studies.     

Composition-Space Behavior of Diffusion-Reaction Systems

Species concentrations in homogeneous well-stirred reacting (WSR) systems with multiple time scales mostly access only a small portion (slow manifold) of the permitted composition space. This offers a mathematically sound basis for reducing complex kinetics. Computational investigation of such slow manifolds in inhomogeneous reaction systems undergoing diffusion in addition to chemical reaction is the subject of this paper. We perform simulations of a one-dimensional diffusion–reaction system from random non-premixed initial conditions to study the accessed composition space for a variety of diffusion to reaction time scale ratios. A detailed hydrogen–oxygen chemical kinetic set (6 species, 14 reactions) is used. Our results show that, to first order, the effect of random advection and diffusion is merely to increase the accessed state-space dimensionality over that of the WSR by the number of relevant mixture fractions. Circumstances under which the above simplification is not accurate are also identified.     

Hydroboration 95 — Relative Effectiveness of the 2-Organylapoisopinocampheylboranes for the Asymmetric Hydroboration of Representative Prochiral Alkenes

Enantiomerically pure and sterically-varied 2-organylapoisopinocampheylboranes (RapBH₂; R=Me, IpcBH₂; R=Et, EapBH₂; Pr, PraBH₂; i-Bu, i-BapBH₂; R=Ph, PapBH₂; and R=i-Pr, i-PraBH₂) were prepared from their corresponding 2-organylapopinenes (2-R-apopinenes; R=Me, Et, Pr, i-Bu, Ph, and i-Pr) and the relative efficiency of these reagents for the asymmetric hydroboration of representative prochiral alkenes compared. With the exception of Ph, the results reveal simple relationships between the steric requirements of the groups R (Me, Et, Pr, i-Bu, Ph, and i-Pr) in these reagents and the moderate to excellent enantioselectivities achieved in the asymmetric hydroboration of six representative prochiral alkenes, such as 2-methyl-1-butene, cis-2-butene, trans-2-butene, 2-methyl-2- butene, 1-methyl-1-cyclopentene, and 1-methyl-1-cyclohexene.     

Chemically Delaminated Free‐Standing Ultrathin Covalent Organic Nanosheets

Covalent organic nanosheets (CONs) are a new class of porous thin two‐dimensional (2D) nanostructures that can be easily designed and functionalized and could be useful for separation applications. Poor dispersion, layer restacking, and difficult postsynthetic modifications are the major hurdles that need to be overcome to fabricate scalable CON thin films. Herein, we present a unique approach for the chemical exfoliation of an anthracene‐based covalent organic framework (COF) to N‐hexylmaleimide‐functionalized CONs, to yield centimeter‐sized free‐standing thin films through layer‐by‐layer CON assembly at the air–water interface. The thin‐layer fabrication technique presented here is simple, scalable, and does not require any surfactants or stabilizing agents.     

Catalyst free sequential one‐pot reaction for the synthesis of 3‐indole propanoates/propanoic acid/propanamides as antituberculosis agents

A highly efficient catalyst free one pot four component synthesis of highly functionalized three‐substituted indole derivatives has been reported. Thus, sequential catalyst free condensation of readily available aldehydes with Meldrum's acid followed by Michael addition of indole resulting three carbon component condensed product and concurrent decarboxylation by the nucleophilic attack of ethanol/water/amines affords three‐indole propanoates/propanoic acid/propanamides in affordable yields. Further, synthesized compounds and standard drugs were evaluated against Mycobacterium tuberculosis H37Rv strain by Alamar blue assay method. Majority of the compounds exhibited the superior activity and specifically compound 4d has MIC 1.6 μg/ml, which is better than the reference drugs used.     

Synthesis of Tri‐functional Core‐shell CuO@carbon Quantum Dots@carbon Hollow Nanospheres Heterostructure for Non‐enzymatic H2O2 Sensing and Overall Water Splitting Applications

A core‐shell structure with CuO core and carbon quantum dots (CQDs) and carbon hollow nanospheres (CHNS) shell was prepared through facile in‐situ hydrothermal process. The composite was used for non‐enzymatic hydrogen peroxide sensing and electrochemical overall water splitting. The core‐shell structure was established from the transmission electron microscopy image analysis. Raman and UV‐Vis spectroscopy analysis confirmed the interaction between CuO and CQDs. The electrochemical studies showed the limit of detection and sensitivity of the prepared composite as 2.4 nM and 56.72 μA μM^?1 cm^?2, respectively. The core‐shell structure facilitated better charge transportation which in turn exhibited elevated electro‐catalysis towards hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and overall water splitting. The overpotential of 159 mV was required to achieve 10 mA cm^?2 current density for HER and an overpotential of 322 mV was required to achieve 10 mA cm^?2 current density for OER in 1.0 M KOH. A two‐electrode system was constructed for overall water splitting reaction, which showed 10 and 50 mA cm^?2 current density at 1.83 and 1.96 V, respectively. The prepared CuO@CQDs@CHNS catalyst demonstrated excellent robustness in HER and OER catalyzing condition along with overall water splitting reaction. Therefore, the CuO@CQDs@CHNS could be considered as promising electro‐catalyst for H₂O₂ sensing, HER, OER and overall water splitting.     

Synthesis,Antitubercular Activity,and Molecular Docking Studies of Novel 2-(4-Chlorobenzylamino)-4-(cyclohexylmethylamino)-pyrimidine-5-carboxamides

Russian Journal of General Chemistry - A novel series of 2-(4-chlorobenzylamino)-4-(cyclohexylmethylamino)-pyrimidine-5-carboxamide derivatives are synthesized and their structures are confirmed by...     

Synthesis and Anticancer Activity of Thiophene-2-carboxamide Derivatives and In Silico Docking Studies

Russian Journal of General Chemistry - A novel series of thiophene-2-carboxamide derivatives are designed and synthesized, and their structures are confirmed by 1H and 13C NMR, and mass spectra....     

On the Invariance of Compressible Navier–Stokes and Energy Equations Subject to Density-Weighted Filtering

The scale invariance properties of compressible Navier–Stokes and energy equations subject to density-weighted filtering are investigated. Scale or filter invariance forms of compressible moment equations require that two forms of generalized central second-order moments be defined—(1) product of two density-weighted sub-filter fluctuations and (2) product of one density-weighted and one un-weighted sub-filter fluctuation. The evolution equations for all required first and second order filtered moments are derived. These results provide the theoretical underpinning for variable-resolution calculations of reacting and compressible turbulent flows.