Metal-free N-formylation of 2-aminophenols using dimethylformamide and CSA

DMF has been proved to be an efficient formylation reagent for 2-aminophenols in the presence of (±) camphorsulfonic acid (CSA) in this work. CSA works as an acid catalyst and a neutralizer of dimethyl amine which is kicked off from DMF. Both electron-withdrawing and electron-donating groups are tolerated. More importantly, the product could be achieved in gram scale with the possibility of further diversifying into biologically interesting structures.