In the presence of as little as one mol-% of a Lewis acid catalyst, e.g. Mg(ClO4)2 or Cu(OTf)2, carboxylic acids can easily and near quantitatively be protected in a decarboxylative esterification at room temperature as methyl, benzyl, or t-butyl esters.
L. Goossen, A. Döhring, Adv. Synth. Catal., 2005, 345, 943-947.