Theoretical studies on the conformation of aldohexopyranoses

Abstract

The σ-charges on various atoms in aldohexopyranoses have been computed by using the MO-LCAO method of Del Re. The potential energy of sixteen aldohexopyranoses in the C1 (D) and 1C (D) conformations have also been calculated. Minimization of the energies of these conformations have been studied by suitably tilting the axial substituents. Considerable release of strain is achieved when tilts of about 4.5° and 3° are given for the axial CH₂OH and the axial OH groups respectively, involved in the Hassel-Ottar effect. The calculated energy-values not only explain the favored conformations assigned from n.m.r. studies but are also found to be in fairly good agreement with the energy values assigned by Angyal.