Sulfonic acid functionalized covalent organic frameworks as efficient catalyst for the one-pot tandem reactions

A covalent organic framework containing hydroxyl groups (HO-COF) has been predesigned and synthesized by the cyclotrimerization reaction of acetyls, which was used as a pre-established network to introduce propyl sulfonic acid through post-synthetic modification strategy, for the fabrication of SO3H-COF with graphene-like multilayer structure. SO3H-COF was employed as an effective heterogeneous catalyst for the synthesis of benzimidazoles, the synthesis of benzodiazepines and one-pot reductive amination of carbonyl compounds. The results indicated that the developed protocol has several advantages, such as high activity, broad substrate scope, short reaction time and excellent yields. The distinctive structures of SO3H-COF endowed the fantastic catalytic properties, good stability and circulation performance.