PBr3-DMF Assisted Elimination of a Highly Hindered Diallylic Tertiary Alcohol in a Bicyclic System: Synthesis of a Key Intermediate Useful for the Total Synthesis of Forskolin

Regioisomeric acetates 12 and 13. obtained by the PBr₃-DMF reaction on a highly hindered diallylic tertiary alcohol, were converted into a key intermediate 15. useful for the total synthesis of forskolin 1     

A Facile Reductive Cleavage of Allylic and Benzylic Esters with Low Valent Titanium Reagents

The reductive cleavage of allylic and benaylic esters 1a-g with titanium(II) reagent derived from Mg/Hg-TiCl yielded the corresponding acids 3a-g and dimeric hydro 4 carbons 2a-g under mild reaction conditions.     

Radiation-Induced Copolymerization of Acrylonitrile with Methyl Acrylate: Synthesis and Characterization

Radiation-induced copolymerization of acrylonitrile with methyl acrylate was carried out in aqueous medium at room temperature. Different compositions of the copolymer were prepared and characterized by IR, ¹H-NMR, thermal, and dielectric studies. NMR spectroscopy was used to determine the composition and stereochemistry of the copolymer. Glass transition temperature values (T_g ) were determined by DSC. Dielectric studies were carried out to understand the segmental motions and the effect of composition on dielectric loss.     

An efficient and novel one-pot synthesis of 2,4,5-triaryl-1<Emphasis Type="Italic">H</Emphasis>-imidazoles catalyzed by UO<Subscript>2</Subscript>(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>·6H<Subscript>2</Subscript>O under heterogeneous conditions

An efficient, convenient, and novel one-pot method of 2,4,5-triaryl-1H-imidazoles synthesis using benzil, arene carbaldehydes, and ammonium acetate, catalyzed by uranyl nitrate hexahydrate [UO₂(NO₃)₂·6H₂O] supported on acidic alumina and resulting in good to excellent yields under heterogeneous conditions, is reported. Formation of a reactants-catalyst complex was confirmed by UV-VIS spectral data. Antibacterial (MIC) and antioxidant activity of the synthesized compounds was also studied.     

Ageing effect on dielectric properties of SnO2, Sb2O3, and their mixed thin films

Thin films of various thicknesses in the form of MIM structures have been prepared from the powders of high purity of SnO₂, Sb₂O₃, and their mixed powders separately by the thermal evaporation technique in a vacuum of 10⁻⁵ Torr. The dielectric properties of these oxide thin films have been studied with ageing time and also with frequency at room temperature. The results obtained have shown that the capacitance and loss tangent of the structures initially fall off rapidly and thereafter they attain a constant value even after ageing the capacitors for about 20 days. The rapid fall of capacitance and loss tangent may be due to the rapid decrease in the density of defects due to ageing time. The results thus obtained on SnO₂, Sb₂O₃, and their mixed thin film capacitors are presented and discussed.