Unexpected Brønsted Acid‐Catalyzed Domino Reaction of 3‐Hydroxyisoindolin‐1‐ones and <i>N</i>‐<i>tert</i>‐Butyl Hydrazones for the Synthesis of 3‐(Hydrazono)isoindolin‐1‐ones

Abstract

A Brønsted acid‐catalyzed aza‐Mannich reaction between 3‐hydroxyisoindolin‐1‐ones and N ‐ tert ‐butyl hydrazones was developed. Under the catalysis of the racemic phosphoric acid or trifluoroacetic acid and mild reaction conditions, this domino reaction allows for efficient synthesis of 3‐(hydrazono)isoindolin‐1‐one derivatives in excellent yields with high chemoselectivities. The E ‐configuration of the hydrazone products was determined by X‐ray single‐crystal diffraction of 5w .