Vasicine as tridentate ligand for enantioselective addition of diethylzinc to aldehydes

The first report of natural l-vasicine as tridentate chiral ligand for the enantioselective addition of diethylzinc to a variety of aliphatic and aromatic aldehydes is described. The ligand generates R-isomer of the secondary alcohols upto 98% ee. The quinazoline structure possibly imparts rigidity to the ligand and hence, consistently high enantioselectivity. The importance of the quinazoline ring was also supported by the reaction with other related ligands, partially lacking the structural features, thus resulting in poor enantioselectivity.     

Solution structure of copper-seamed C-alkylpyrogallol[4]arene nanocapsules with varying chain lengths

The stability of copper-seamed C-alkylpyrogallol[4]arene hexamers with varying chain lengths in solution has been studied using small-angle neutron scattering (SANS). The progression in diameter of spherical capsules with increasing alkyl chain lengths of copper-seamed hexamers in solution suggests both robustness as well as a close correlation between the solid phase and solution phase structures.     

Some sequential procedures for ranking multivariate normal populations

Summary Considerk p-variate normal populationsπ _i with meansμ _i and common covariance matrix Σ, i.e.,π _i :N(μ _i ,Σ). The problem is to design a sequential procedure to rank these populations with respect to some distance function. We consider two distance functionsμ′ _i μ _i andμ′ _i Σ ^-1 μ _i . Procedures on the lines of Chow and Robbins [3], Paulson [5] and Hoel and Majumdar [4] are obtained. Research supported by National Research Council of Canada and Canada Council.     

Meta-Nitro-Benzoylacetanilide as a Reagent for Iron

Meta-nitrobenzoylacetanilide (NBAA) forms violet coloured chelate Fe(NBAA)₂ with Fe (III) in 60% ethanol medium with λ_max at 530 nm. The molar absorptivity, sensitivity, effect of diverse ions in spectrophotometric determination of iron, and effect of ionic strength on the stability constant have been investigated. The free energy of formation of the chelate, enthalpy change and the entropy change have also been calculated and are found to be −9.44 kcal/mole, −4.97 kcal/mole and 15.23 e.u. respectively.     

A joint characterization of directed divergence,inaccuracy, and their generalizations

Starting with an additive property for distributions of two statistically independent random variates in terms of different sum functions, we have characterized two general measures associated with two distributions of a discrete random variate. One of these measures is logarithmic, while the other contains powers of variables. An interesting aspect is that under suitable additional boundary conditions the logarithmic measure leads to measure of information (directed divergence) studied by Kullback and measure of inaccuracy studied by Kerridge, while the other solution leads to their parametric generalizations.     

Investigation of encapsulation of insulin biotemplate within C-methylresorcin[4]arenes

Solution structure of insulin templated C-methyl resorcin[4]arene nanocapsules has been investigated using neutron scattering. The insulin biotemplate has enhanced the limits of encapsulation and enabled formation of a larger spherical molecular host.     

Synthesis of some new mesoionic heterocycles

The synthesis of various substituted 1-hydroxy-2-chloroacetyl-6-thia-10b-aza-2a-azoniaaceanthrylene hydroxide inner salt, 1-hydroxy-6-thia-10b-aza-2a-azoniaaceanthrylene hydroxide inner salt, 1-hydroxy-2-piperidinoacetyl-6-thia-10b-aza-2a-azoniaaceanthrylene hydroxide inner salt is described. The ir is also included.