Dimethyl Sulfoxide Participating in Copper(I) Iodide‐Catalyzed Cascade Oxidation/Formylation Reactions: The Synthesis of α‐Formylpyrroles from 2,3‐Dihydro‐1 H ‐pyrroles

An efficient copper‐catalyzed tandem oxidation/α‐formylation reaction of 2,3‐dihydro‐1 H ‐pyrroles in an oxygen atmosphere has been developed. The new reaction is conducted in dimethyl sulfoxide (DMSO), which serves as both the carbonyl carbon source and solvent, in the presence of trifluoroacetic acid to directly generate structurally diverse α‐formylpyrrole derivatives in one pot in moderate to good yields. Sensitive aldehyde groups remain intact in the presence of an oxidant, trifluoroacetic acid and a transition metal salt. A possible mechanism is presented. magnified image