An iron-loaded metal–organic framework (CAU-27-Fe) as effective heterogeneous catalyst for the direct C–H amination of ethers using NH-heterocycles

Abstract

Carbon-nitrogen moieties are found in a wide range of compounds, ranging from bulk materials to fine chemicals, such as biological and pharmaceutical ingredients. More sustainable and efficient methods for constructing C-N bonds are desired and cross-dehydrogenative amination has emerged as an environmentally friendly and selective approach to fulfill this need. However, the potential of heterogeneous catalysis remains largely unexplored in this area. In this work, we investigate a straightforward strategy to immobilize FeCl2 on the linkers of a metal–organic framework (i.e. CAU-27-BIPY), which is capable of performing the direct C-N coupling of benzimidazole and THF using tert-butylhydroperoxide (TBHP) with an excellent yield of 92 % under mild reaction conditions. The versatility and applicability of this approach are demonstrated by successfully coupling a wide variety of NH-heterocycles and ethers, including for the synthesis of key pharmaceutical precursors. Furthermore, the Fe-loaded MOF catalyst preserves its activity and structure over four consecutive runs.