Ab initio HF/6-31G* Methode was employed to calculate  the bond length in 2- phosphinanes  when electronegative groups was at C-2 tend axial and equatorial positions. The magnitude of  the anomeric effect depends on the nature of the substituent, the effect of the substituent can be seen by comparing the bond length in 2-chloro and 2-boromo substituented phosphinanes. The effect of anomeric eff...

Many natural products of biological interest contain [6,5]- and [6,6]-spiroketal moieties that can adopt various configurations, benefiting or not from anomeric conformation stabilizing effects. The spiroketal fragments are often important for the biological activity of the compounds containing them. Most stable spiroketal stereoisomers, including those benefiting from conformational anomeric e...

The urine from three patients with marmosidosis was found to contain abnormally high amounts of mannose-containing oligosaccharides. The highest yield (123 to 430 mg per liter of urine) was obtained of a trisaccharide, which was isolated and characterized. The isolation procedure included ultrafiltration, gel chromatography on Sephadex G-25, purification by preparative zone electrophoresis, and...

Molecular orbital calculations have been carried out on 2-fluorotetrahydropyran and 2-chlorotetrahydropyran as models for examining the anomeric effect in glycosyl halides. The calculated population of chair conformers depends on the solvent and for the axial form of fluoro derivative decreases from 90.6 % in dioxan to 37.0 % in water. For chloro derivative the dependence is less pronounced; th...

A natural bonding orbital (NBO) analysis of phosphate bonding and connection to experimental phosphotransfer potential is presented. Density functional calculations with the 6-311++G(d,p) basis set carried out on 10 model phosphoryl compounds verify that the wide variability of experimental standard free energies of hydrolysis (a phosphotransfer potential benchmark) is correlated with the insta...

The 13C n.m.r. spectrum of Forssman hapten was obtained at 25.16 MHz in [3H] chloroform/[2H] methanol (1:1, v/v), using purified glycosphinogolipid from canine intestinal mucosa (glycolipid I). All amide, olefin, anomeric, intersaccharide glycosidic ether, amide linkage, methyl and many methylene resonances were resolved and assigned. Analysis of the anomeric region reveals the following pentag...

Abstract The goal of this research is to further investigate NKT cell activation using sulfatide analogues. cells have been shown play a significant role in mediating inflammatory immune responses and because this, there has strong interest pharmacologically regulating compartment fight cancer. recognize lipids that are loaded on CD1d molecules the surface cells, it structural modifications the...

Oxazinane rings can undergo isomerization or transformation to 5-membered tuned by the anomeric effect.

Carbohydrates are an extremely complex group of isomeric molecules that have been difficult to analyze in the gas phase by mass spectrometry because (1) precursor ions and product ions to successive stages of MS(n) are frequently mixtures of isomers, and (2) detailed information about the anomeric configuration and location of specific stereochemical variants of monosaccharides within larger mo...