The exocyclic hydroxymethyl group of the -D-1-amino-1-deoxyglucopyranose can rotate around the carbon-carbon bond. Potential energy surface for this rotation has been investigated using ab initio quantum chemical methods. Relevant stationary points, including for the first time rotational transition states have been characterized by full geometry optimization using basis sets 6-31G(d) and 6-31G(2d,lp). There is a total of six stationary points along the hydroxymethyl rotational surface, including three minima and three transition states were identified. The effects of basis set augmentation and electron correlation on the relative energies are small; the relative energies for each stationary point vary by less than kJ/mol for all levels of theory considered. The final barriers to hydroxymethyl rotation ranged from 15 to 41 kJ/mol.
