Ab initio study of the energetics of protonation and deprotonation of the methyl 3-amino-2,3-dideoxyhexopyranosides isomers

In order to determine the preferred protonation and deprotonation sites for four isomers of methyl 3-amino-2,3-dideoxyhexopyranoside with the α/β-d-arabino and β/α-d-ribo configurations, ab initio quantum chemical calculations were performed in the gaseous phase with two methods: Restricted Hartree Fock (RHF) and Møller-Plesset (MP2), as well as after consideration of the solvation effects within the Polarizable Continuum Model (PCM). The energy and Gibbs free energy of the protonation and deprotonation were calculated using a Gaussian 6-31+G* basis set. Hydrogen bond lengths in the studied compounds were calculated using theoretical methods applied (RHF