Gytis Vektaris

Ab initio Computational Insight into the Interaction of Alkyl-substituted Ethene and Sulfenyl Halide

The ab initio calculations approach was used to determine the mechanism of interaction between propene and a sulfenyl halide. The second-order Møller-Plesset corrections for the electron correlation energy were applied to calculate the most probable Gibbs Free Energy profiles for the selected reaction. All optimized structures were confirmed by vibrational frequency analysis and intrinsic reaction coordinate calculations. Two possible reaction pathways were proposed and evaluated to conclusively characterize the reaction. The reaction proceeds via formation of a cyclic episulfonium intermediate, stereoselective ring opening of the episulfonium intermediate by the chloride anion, and isomerization of the adduct of the kinetically controlled reaction into the thermodynamically favorable product. Graphical Abstract Ab initio Computational Insight into the Interaction of Alkyl-substituted Ethene and Sulfenyl Halide

Substitution Effects on Reactivity of N-Acyl-2-amino-2-desoxyglucopyranoses. Quantum Chemical Study

Institute of Theoretical Physics and Astronomy, A. Gostauto 12, 2600 Vilnius, Lithuania. Tel.: (370-2) 620953. Fax: (370-2) 225361. E-mail: vektaris@itpa.lt†Presented at the 4th Electronic Conference on Synthetic Organic Chemistry, September 1-30, 2000, (Paper A0046).* Author to whom correspondence should be addressed. E-mail: avekt@bchi.ltReceived: 22 November 2000 / Accepted: 28 November 2000 / Published: 21 December 2000Abstract: Quantum mechanical calculations were carried out to study the molecular geometry and electronic structure of 2-amino-2-desoxyglucopyranose (AG) and the N-acetyl-, N-ethanoyl-, series of N-phthalimidoalkanoyl-AG. The total charge density, electrostatic potential, spatial distribution and positions of HOMO and LUMO of N-acyl-AGs with respect to their substitutes yield information on the reactivity of the molecules.Keywords: N-Acyl-2-amino-2-desoxyglucopyranoses, quantum chemistry, reactivity.Introduction2-Amino-2-desoxyglucopyranoses (AG) containing N-acyl functional group residues display unique chemical and biological behavior Experimentally, the structure of N-substituents on 2-amido-AG have been shown to significantly affect the reactivity of the glucopyranose skeleton. In some cases, their reactivity is significantly enhanced, allowing for selective reactions, which usually cause chemical or conformational rearrangements [1-5]. In other cases, the N-acyl-AG molecule becomes unreactive or the glucopyranose ring is destroyed, which is synthetically disastrous [1-6]. It would be a significant