An efficient protocol for regioselective ring opening of epoxides using sulfated tungstate: application in synthesis of active pharmaceutical ingredients atenolol,propranolol and ranolazine

Sulfated tungstate was found to be a new and highly efficient catalyst for opening of epoxide rings by amines to give β-amino alcohols with high regioselectivity. Various advantages associated with this novel and environmental friendly protocol include solvent-free conditions, short reaction times, high product yields, simple workup procedure and easy recovery and reusability of the catalyst. This protocol has been applied for the synthesis of active pharmaceutical ingredients atenolol, propranolol and ranolazine.     

Coordination‐Based Molecular Assemblies of Oligofurans and Oligothiophenes

Molecular assemblies (MAs) of oligofurans and oligothiophenes were formed from solutions on various substrates. These films were obtained by alternating deposition of organic chromophores (oligofurans or oligothiophenes) and a palladium salt. These coordination‐based MAs were characterized by UV/Vis spectroscopy, spectroscopic ellipsometry, atomic force microscopy (AFM), X‐ray reflectivity (XRR), X‐ray photoelectron spectroscopy (XPS), and electrochemistry. The MAs exhibit similar electrochemical behavior and their growth and structure are apparently not affected when different organic template layers are used. The density of the MAs is a function of the structure of the molecular component. The oligothiophene density is approximately 50 % higher than that observed for the oligofuran‐based assemblies. The optical and electrochemical properties of the MAs scale linearly with their thickness. The UV/Vis data indicate that upon increasing the film thickness, there is no significant conjugation between the metal‐separated organic chromophores. DFT calculations confirmed that the HOMO–LUMO gap of the surface‐bound oligofuran and oligothiophene metal oligomers do not change significantly upon increasing their chain length. However, electrochemical measurements indicate that the susceptibility of the MAs towards oxidation is dependent on the number of chromophore units.     

Bifurcation diagrams in relation to synchronization in chaotic systems

We numerically study some of the three-dimensional dynamical systems which exhibit complete synchronization as well as generalized synchronization to show that these systems can be conveniently partitioned into equivalent classes facilitating the study of bifurcation diagrams within each class. We demonstrate how bifurcation diagrams may be helpful in predicting the nature of the driven system by knowing the bifurcation diagram of driving system and vice versa. The study is extended to include the possible generalized synchronization between elements of two different equivalent classes by taking the Rössler-driven-Lorenz-system as an example.     

Rearrangement of dicarboranyl methyl cation to icosahedral C3B9H12+: An ab initio dynamics view

Closo-carborane anions are prominent, whereas the cations of the same are less abundant in the literature. As these ions have similar size and are weakly coordinating, the ionic liquids of these two ions could have important applications in many areas of chemistry. In view of limited number of polyhedral carborane cations available, we revisited the rearrangement of dicarboranyl methyl cation (7-CH₂ 7,9-nido-C₂B₉H₁₀⁺) using ab initio molecular dynamics calculations with metadynamics. Our simulations confirmed the concerted mechanism of the rearrangement. We believe this work will resume the interest in its synthesis and carborane cations in general.