The stereochemical course of the oxidation of chiral oxazolidinone-substituted enecarbamates has been studied for singlet oxygen ((1)O(2)), dimethyldioxirane (DMD), and m-chloroperbenzoic acid (mCPBA) by examining of the special structural and stereoelectronic features of the enecarbamates. Valuable mechanistic insight into these selective oxidations is gained. Whereas the R(1) substituent on t...

Stable and easy-to-handle zwitterions containing carbanion and pyridinium moieties were synthesized, and their structural studies by both X-ray crystallography and theoretical methods revealed the stereoelectronic effect in the zwitterionic 'C(-)-C-N(+)' system.

The polyproline type II (PPII) helix is a prevalent conformation in both folded and unfolded proteins, and is known to play important roles in a wide variety of biological processes. Polyproline itself can also form a type I (PPI) helix, which has a disparate conformation. Here, we use derivatives of polyproline, (Pro)10, (Hyp)10, (Flp)10, and (flp)10, where Hyp is (2S,4R)-4-hydroxyproline, Flp...

In three 9-silyltriptycenes bearing chlorine, bromine and the methyl group in one of the peri positions, the silyl group suffers extreme hindrance of its reorientational motion. Owing to this, separate signals of the individual silyl group protons could be observed in NMR spectra at relatively high temperatures. For each compound, the measured values of J couplings of these protons to the 29Si ...

in this research, we report the results of dft calculations using xc-hybrid functional, b3lyp and employ nbo interpretation to investigate the stereoelectronic effects. electrostatic and steric impacts on the conformational properties of 1,2-difluorodiazene (1), 1,2-dichlorodiazene (2) and 1,2-dibromodiazene (3) are also studied. factors determining the thermodynamically stable molecular struct...

According to a prevailing theory, (2S,4R)-4-hydroxyproline (Hyp) residues stabilize the collagen triple helix via a stereoelectronic effect that preorganizes appropriate backbone torsion angles for triple-helix formation. This theory is consistent with the marked stability that results from replacing the hydroxyl group with the more electron-withdrawing fluoro group, as in (2S,4R)-4-fluoroproli...

NBO analysis, hybrid density functional theory (B3LYP/6-311+G**) based methods were used to study the anomeric effects (AE), Stereoelectronic interactions, dipole-dipole interactions on the conformational properties of 1-Fluoro-N, N-dimethylmethanamine (1) and phosphorus (2) and arsenic (3) analogues.Moreover, relationships between stability of the anti-conformations of 1-Fluoro-N, N-dimethylme...

Abstract It is now established that crystalline cellulose held together not just by hydrogen bonding, but also dispersion forces and electrostatic attraction modulated stereoelectronic factors such as the exo-anomeric effect. The surface chains of native microfibrils differ in C6 conformation from therefore form different bonds, both outward inward. Dispersion forces, influenced conformation, o...