Boric Acid as Highly Efficient Catalyst for the Synthesis of Phenols from Arylboronic Acids

A simple, efficient, and environmentally benign boric acid catalyzed methodology for the ipso‐hydroxylation of arylboronic acid to phenol has been developed using aqueous hydrogen peroxide as an oxidizing agent and ethanol as the solvent. The versatility of this protocol is that the reactions were performed at room temperature in short reaction time under metal‐, ligand‐, and base‐free conditions.     

Reactivity between acetone and single-stranded DNA containing a 5′-capped 2′-fluoro-N7-methyl guanine

DNA-mediated catalysis is an emerging field in bioorganic chemistry and chemical biology. However, the functional group diversity and known reactivity of DNA (A, T, C, and G) is relatively limited in scope. This relatively defined reactivity can limit the utility of DNA as a catalyst. In an effort to expand the functional group diversity and chemical reactivity of DNA, we sought to explore reactions involving single-stranded DNA equipped with a stabilized variant of N7-methyl guanine (2′-fluoro-5′-N7-methyl guanine). Here, we show that 5′-capped 2′-fluoro-N7-methyl guanine-labeled single-stranded DNA reacts with a ketone to afford a ketone-labeled DNA. This reaction likely proceeds through a reactive ylide or N-heterocyclic carbene. Taken together, our findings suggest that 2′-fluoro-5′-N7-methyl guanine is a stable adduct that can be selectively incorporated into ssDNA and functionalized with a ketone moiety by reaction with a simple ketone. Incorporation of this nucleoside into ssDNA may be useful for the evolution of novel deoxyribozymes that catalyze new reactions, including those which proceed via a reactive ylide or N-heterocyclic carbene-mediated chemistry.     

A tug-of-war between electronic excitation and confinement in a dynamical context

Quantum fluid density functional theory has been used to study the time evolution of various reactivity parameters such as hardness, electrophilicity, entropy, chemical potential, polarizability, electronegativity etc. in a confined environment during time dependent processes like atom-ion collision and atom-field interaction. Responses in the reactivity parameters of the helium atom, in the dynamical context, for ground state as well as in excited state, have been reported. The confinement is incorporated through a Dirichlet type boundary condition. With a decrease in the size of the cylindrical box, the system gets harder and less polarizable. Simultaneous excitation and confinement may bring back the ground state behavior.     

Rheological signatures of ethylene methyl acrylate‐multiwalled carbon nanotube nanocomposites

The rheological behavior of nanocomposites based on multiwalled carbon nanotube (MWNT) with three commercial grades of ethylene methyl acrylate (EMA) copolymers containing 9, 24, and 30 wt% methyl acrylate (MA) was investigated under dynamic and steady shear flow (in a capillary) conditions. Storage modulus (in dynamic shear) value increases especially at higher frequency levels due to increased polymer‐filler interactions. Both the unfilled and filled composites exhibit rheological behavior of non‐Newtonian fluids. In both steady shear and capillary flow, the nanocomposites register a slightly higher viscosity than neat EMAs, with dependence on the MWNTs content. All systems with various loading of MWNTs represent an increase in elastic response with increasing frequency. The die swell decreases with the MWNTs loading. Dynamic and steady shear rheological properties register a good correlation in regard to the viscous versus elastic response of such systems inline with the Cox–Merz concept. Increased MA content leads to inferior dispersion of MWNTs in EMA matrix. Morphological studies exhibit that MWNTs become more aligned along longitudinal direction after extrusion leading to improved dispersion. Copyright © 2010 John Wiley & Sons, Ltd.     

Antimicrobial C-glucoside from aerial parts of Diospyros nigra

A new C-alkylglucoside, diospyrodin [beta-1C-(1'S*,2'R*,3'R*,4'S*-1',2',3',4',5'-pentahydroxypentyl)-glucopyranoside] (1) has been isolated as its nonaacetate from the leaves and stems of Diospyros nigra. Its structure was elucidated on the basis of chemical and spectral properties and a single crystal X-ray analysis. It showed antimicrobial activity against Gram-positive and Gram-negative bacteria.     

Toward understanding the scope of Baylis-Hillman reaction: synthesis of 3-(2- hydroxyphenyl)indolin-2-ones and polycyclic fused furans

A facile one-pot synthesis of 3-(2-hydroxyphenyl)indolin-2-ones has been developed via the TiCl₄-mediated Baylis-Hillman (B-H) reaction of N-substituted isatins and cyclohex-2-enone, followed by treatment of the in situ generated B-H alcohols with aq HBr. Baylis-Hillman reaction of aromatic cyclic 1,2-diones with cycloalk-2-enones under the influence of TiCl₄ has been successfully performed and the resulting Baylis-Hillman adducts have been conveniently transformed into pentacyclic and hexacyclic fused furan derivatives.     

IUCAA: genesis of a unique research centre

The European Physical Journal H - The Inter-University Centre for Astronomy and Astrophysics (IUCAA) is the second Inter-University Centre established by the Government of India for promotion of...