Reactions of t-butyl peresters—III Cuprous bromide-catalyzed reaction of peresters with ethers

Aliphatic and cyclic ethers react smoothly with t-butyl peracetate and t-butyl perbenzoate at 67–90° in the presence of cuprous bromide. The first products of this reaction are the acyloxy derivatives of the ethers, which are unstable under the chosen experimental conditions and decompose to the corresponding carboxylic acids and unsaturated ethers. Thus, 2,3-dihydrofuran was prepared from 2-benzoyloxytetrahydrofuran in a 66% yield. The unsaturated ethers add t-butyl alcohol to give the corresponding acetals, this step being catalyzed by the carboxylic acid. This reaction is general for ethers containing two adjacent methylene groups, such as n-propyl and n-butyl ethers, tetrahydrofuran, and tetrahydropyran. Diethers, such as 1,4-dioxane and 1,2-dimethoxyethane, give more stable benzoyloxy derivatives, which decompose slowly on prolonged heating to give the expected acetals in low yield.