Hypervalent Iodonium-catalysed Debenzylation of Aryl Benzyl Ethers

Abstract

This work entails an alternative, convenient and efficient debenzylation method for phenolic benzyl ethers containing electron-rich substituents on the phenolic ring using a catalytic amount of Barluenga’s reagent (IPy2BF4) in the presence of triflic acid as shown in Scheme 1. Scheme 1: Proposed general method for the debenzylation of benzyl ethers using IPy2BF4 in acidic conditions A number of mono-substituted aryl benzyl ethers containing electron donating (EDG) or electron withdrawing group (EWG) substituent at the ortho, meta and para position were employed to probe the electron effect of the debenzylation method. The electron donating groups (EDG) showed better rates as compared to electron withdrawing groups (EWG), while halogenated (mon-substituted) derivatives showed lower yields. We found that this method works better than previously published methods for debenzylation of a number of estrone derivatives.