Stable axial-rich chair conformer of myo-inositol derivatives due to introduction of two adjacent bulky silyl protections

Lithium hydride as an efficient reagent for the preparation of 1,2-anhydro inositols: Does the reaction proceed through 'axial rich' conformation?

scyllo-Inositol derived 1,2-trans-diequatorial halohydrins can be efficiently converted to the corresponding epoxides in the presence of lithium hydride. The structure of one of the epoxides was determined by single crystal X-ray diffraction analysis. This provides a potential route for the preparation of ring modified inositol derivatives. DFT calculations suggest that this epoxide formation could be proceeding through the intermediacy of the cyclohexane ring-inverted axial-rich conformer (1,2-trans-diaxial halohydrin). This is supported by the results of DFT calculations on the formation of inositol orthoformate, where the product is locked in the axial-rich conformation, while the starting inositol has the equatorial-rich conformation.

Inositols: The Effect of Bulky Substituents on Conformations

Inositols have been converted into their triphenylsilyl derivatives. In all cases only five substituents could be introduced, the remaining free hydroxy group being hindered. The derivative of myo-inositol and one of two of neo-inositol were found to be in the inverted chair conformation, but those of other inositols are in the normal chair form. The structures of two penta-substituted derivatives have been determined by X-ray crystallography.