Erbium triflate: A valuable and non-toxic catalyst for the synthesis of acylals and enol esters

Abstract

Er(OTf)3 was found to be an effective Lewis acid catalyst for the conversion of aldehydes into acylals. Unlike most of the other known catalysts, it is able to give acylals from acetic anhydride as well as other anhydrides. Moreover, it can react with cyclic ketones to give unstable acylals, which can be isolated as enol esters. Other advantages are the very low loading of catalyst, excellent chemoselectivity, and solvent-free and mild conditions.