Table of Contents

Abstract: n/a

Abstract: Enantiomerically pure, five membered cyclic nitrones, easily obtained in large amounts from protected hydroxyacids and aminoacids such as D- and L-tartaric, L-malic, and L-aspartic acids, give cycloaddition reactions with a good diastereocontrol. The adducts of L-malic and L-aspartic acids derived from addition of nitrones to dimethyl maleate and g-crotonolactone were easily converted into enantiopure pyrrolizidinones, which can be transformed into polyhydroxypyrrolidines or polyhydroxypyrrolizidines, both interesting compounds as potential glycosidase inhibitors. The method is suitable for natural products synthesis as exemplified by a straightforward and convenient access to the pyrrolizidine alkaloid necine base (–)-hastanecine, as well as to indolizidine alkaloids, i.e. (+)- lentiginosine.

Abstract: A method to reduce the nitro moiety in dimethyl 4-nitro-4-[1-[2(methoxycarbonyl)ethyl]]heptanedioate using a T-1 Raney nickel catalyst in an acidic environment is reported. The method avoids facile lactam formation.

Abstract: The inorganic property (I) and organic property (O) values of general organic groups are re-proposed here. Both I and O values of drug and biological molecules or groups can be calculated based on their common group values. The calculation can be performed easily on-line through JavaScript. Similar calculation can be done for the drug and biological molecular group electronegativity (X) according to the author's published paper. The calculation of lipophilicity (π or logP) parameter of (macro)molecules (like proteins) can also be performed on-line through JavaScript. Two equations expressed with I and O are provided here to define the hydrophobicity of each amino acid. The correlations of inorganic property and organic property values with other parameters are also discussed. These calculated parameters combined with other parameters can be used for QSAR studies in some drug molecules.

Abstract: We use a method for the calculation of the molecular dipole ( μ ) and quadrupole (θ ) moments and dipole-dipole (α ), dipole-quadrupole ( A) and quadrupole-quadrupole (C ) polarizabilities which we have successfully applied to the benzothiazole (A)-benzobisthiazole (B) linear oligomer A-B13-A. Two model rotational isomers have been characterized: (1) the fully-planar (000) conformation; and (2) a rotational isomer with each unit rotated in the range 1 - 10° in the same direction (+++). For isomer 000, μ is smaller than for +++. The calculation of α, A and C has been carried out by the interacting induced dipoles polarization model that calculates tensor effective anisotropic point polarizabilities (method of Applequist et al.). The values of A are specially sensitive to μ which varies under rotation. This fact explains the great values of A_x,xx for the +++ polar isomer. It is found that small torsional changes can enhance solubility by a clear increasing of the hydrophilic accessible surface area. However, the torsion of the oligomer varies the value of μ and so modifies α, C , and, specially, A. For conformer +++, polarization effects occur even when each unit is rotated only f = 1°. The observed effect is an increase in μ and, hence, in α , C , and, specially, A.