Tuning the reactivity of glycosyl donors by selective introduction of different protecting and leaving groups enabled highly efficient oligosaccharide synthesis. Utilising both phenylseleno and ethylthio glycosides in combination with the cyclohexane-1,2-diacetal (CDA) protecting group provided four different levels of reactivity. One-pot sequential glycosidation of three components gave trisaccharides and tetrasaccharides.