Epoxides are one of the most versatile functional groups in synthetic chemistry, and their cleavage has been investigated in a variety of contexts (Scheme 1). Nucleophilic opening of epoxides can be broadly characterized as either intermolecular or intramolecular. Intramolecular opening of epoxides by pendant alcohols is a known route to a variety of oxygen heterocycles, including furans, pyrans, and medium-sized rings, and this strategy has been applied on numerous occasions in natural products synthesis. Several laboratories have established that "temporary tethering" is an effective strategy for regiocontrol in intermolecular ring-opening reactions of epoxides. In such reactions, a Lewis acid or organocatalyst non-covalently binds to both the substrate and the nucleophile and templates attack at a single site of the epoxide. In contrast to these two areas, the use of covalent tethers for epoxide opening is much less established, and most explorations have focused on carbonates, carbamates, and trichloroacetamidates. Of these tethers, only carbonates cleave epoxides with a masked hydroxy group.