Cu-MOFs as active, selective and reusable catalysts for oxidative C–O bond coupling reactions by direct C–H activation of formamides, aldehydes and ethers

Abstract

MOFs with Cu²⁺ centers linked to four nitrogen atoms from azaheterocyclic compounds, i.e., pyrimidine [Cu(2-pymo)₂] and imidazole [Cu(im)₂], are active, stable and reusable catalysts for oxidative C–O coupling reactions by direct C–H activation of formamides, aldehydes and ethers. The measured catalytic activities are clearly superior to other homogeneous cupric salts, especially for the [Cu(im)₂] MOF. The previously reported activity of the Cu²⁺ centers for cumene oxidation allows the use of the MOF as a bifunctional catalyst for olefin epoxidation with O₂. The overall catalytic process consists of a cascade reaction in which the Cu-MOF first produces cumyl hydroperoxide and then the same Cu²⁺ centers catalyze the oxidative C–O coupling reaction using the generated hydroperoxide as the oxidant.