An ab initio study of dimethoxymethane protonation and its relevance to glycoside hydrolysis

Abstract

An ab initio study of the protonation of the various conformers of dimethoxymethane using Gaussian 82 and 86 and 6-31G* basis set shows that nσ* delocalization decreases the proton affinity of an acetal oxygen, and that syn-periplanar alignment of a lone pair with the leaving group lies on the pathway to the transition state and is indeed ∼0.5 kcal mol^–1(1 kcal = 4.184 kJ) more favourable than the antiperiplanar arrangement.