Acid- and Base-Stable Esters: A New Protecting Group for Carboxylic Acids

An acid- and base-stable protecting group for carboxylic acids is described. The esters of (2,6-dichloro-4-methoxyphenyl)(2,4-dichlorophenyl)methanol are stable to Bronsted and Lewis acids, Bronsted bases, and a wide variety of nucleophiles; however, the esters can be conveniently deprotected by a solvolytic displacement reaction with 20% trifluoroacetic acid.