Mild and efficient method for the cleavage of benzylidene acetals by using erbium (III) triflate.

Er(OTf)3 is proposed as new efficient Lewis acid catalyst in a mild deprotection protocol of benzylidene derivatives. In a modified procedure, where acetic anhydride is used as the reaction solvent, the simultaneous cleavage of the benzylidene acetal and the peracetylation of the substrates is obtained in quantitative yields and very short reaction times.