Influence of acyl groups on glucopyranoside reactivity in Lewis acid promoted anomerisation

Lewis acid promoted anomerisation has potential in O- or S-glycoside synthesis. Herein, the anomerisation kinetics of thirty-one β-d-glucopyranosides was determined to determine how particular acyl protecting groups and their location influence reactivity towards a Lewis acid promoted reaction. The replacement of acetyl groups with benzoyl groups led to reduced reactivity when located at O-3, O-4 and O-6. However a reactivity increase was observed when the acetyl group was replaced by a benzoyl group at O-2. The 2,3,4,6-tetra-O-(4-methoxy)benzoate had an ∼2-fold increase in rate when compared to the tetrabenzoate.