A short and concise route to total synthesis of Dendrodolide L

A short and efficient method for the stereoselective synthesis of Dendrodolide L has been developed from inexpensive and commercially available starting material. This convergent synthesis utilizes Jacobsen kinetic resolution, regioselective ring-opening of epoxide and Yamaguchi macrolactonization as key steps.     

Oxidation of Ru(III)‐Bound Thiocyanate with Peroxomonosulfate: Kinetic and Mechanistic Studies

The reaction of [Ru^III(edta)(SCN)]^2? (edta^4? = ethylenediaminetetraacetate; SCN^? = thiocyanate ion) with the peroxomonosulfate ion (HSO₅^?) has been studied by using stopped‐flow and rapid scan spectrophotometry as a function of [Ru^III(edta)], [HSO₅^?], and temperature (15–30ºC) at constant pH 6.2 (phosphate buffer). Spectral analyses and kinetic data are suggestive of a pathway in which HSO₅^? effects the oxidation of the coordinated SCN^? by its direct attack at the S‐atom (of SCN^?) coordinated to the Ru^III(edta). The high negative value of entropy of activation (ΔS^≠ = ?90 ± 6 J mol^?1 deg^?1) is consistent with the values reported for the oxygen atom transfer process involving heterolytic cleavage of the O‐O bond in HSO₅^?. Formation of SO₄^2?, SO₃^2?, and OCN^? was identified as oxidation products in ESI‐MS experiments. A detailed mechanism in agreement with the spectral and kinetic data is presented.     

Angular momentum and cross sections for fusion with weakly bound nuclei: breakup,a coherent effect

Results for the cross section and average angular momentum for complete fusion at energies around the Coulomb barrier are presented for 7Li with 165Ho. Comparison of the cross sections with a one-dimensional barrier penetration model, using a potential consistent with the measured elastic scattering, showed a reduction above the barrier and an enhancement below it. An increase in the measured average angular momentum, , above the barrier and its consistency with that obtained from the fusion excitation function for weakly bound nuclei, is reported. These results together with a reanalysis of existing data conclusively demonstrate that the effect of breakup on fusion is coherent, like coupling to any nonelastic channel.     

Response of regional brain glutamate transaminases of rat to aluminum in protein malnutrition

Background  

The mechanism of aluminum-induced neurotoxicity is not clear. The involvement of glutamate in the aluminium-induced neurocomplications has been suggested. Brain glutamate levels also found to be altered in protein malnutrition. Alterations in glutamate levels as well as glutamate-α-decarboxylase in different regions of rat brain has been reported in response to aluminum exposure. Thus the study of glutamate metabolising enzymes in different brain regions of rats maintained on either normal or restricted protein diet may be of importance for understanding the neurotoxicity properties of aluminium.     

Preparation of some nickel(II) and copper(II) complexes of the SCHIFF-Base derived from Acetophenone and Ethylenediamine

Preparation and properties of the following Ni^II and Cu^II complexes of the Schiff base derived from acetophenone and ethylenediamine (BAPE) and also of the mixed Ni^II and Cu^II chelates with BAPE and acetylacetone (acac-H) are described: In each case the Schiff base, BAPE, acts as a neutral bidentate ligand. The complexes are characterised by electronic spectra, magnetic susceptibilities, conductivities and elemental analyses. Pseudotetrahedral structure is proposed for M(BAPE)C1₂, while tetragonal structure for [M(BAPE)(acac)(H₂O)₂]C_lO₄ (M = Ni and Cu). The complex [Ni(BAPE) (acac)]ClO₄ has been found to be square planar.     

Titration curves of p-aminobenzoic acid–formaldehyde polymer in relation to its structure

p-Aminobenzoic acid and formaldehyde were condensed in the presence of acid catalyst. The linear condensation polymer thus obtained was then separated into four fractions by a fractional precipitation method. Conductometric titrations were carried out on these four polymer fractions and the conglomerate in nonaqueous solvents with acid as well as base. The titration curves indicated a large number of additional breaks before the complete neutralization of COOH or NH₂ groups. These observations have been interpreted in terms of degree of polymerization and the structure of the polymer.     

Electrophoretic and viscometric studies of the interactions of polymethacrylamide and polyacrylamide with electrolytes in aqueous solutions

Free electrophoresis and viscometry were used to study the effects of salts (perchlorates, thiocyanates, chlorides and sulphates of uni- and bivalent metals) on the properties of polyacrylamide and polymethacrylamide in aqueous solutions. In salt solutions, in the electric field both polymers behave as polyanions. It may be inferred from electrophoretic measurements that both anions and cations are bound on the polymer chain; the degree of binding depends on the nature of the ions. The viscometric data show that there is a pronounced salting-in effect of cations (increasing with increasing surface charge density); the effect of anions is either secondary (for polyacrylamide) or rather unfavourable to dissolution (for polymethacrylamide).