PPTS‐Catalyzed Bicyclization Reaction of 2‐Isocyanobenzaldehydes with Various Amines: Synthesis of Diverse Fused Quinazolines

A PPTS (pyridinium p ‐toluenesulfonate)‐catalyzed bicyclization reaction of 2‐isocyanobenzaldehydes as 1,5‐dielectrophiles with various amines has been developed. The reaction not only provides a simple and efficient strategy for the assembly of structurally diverse fused quinazoline derivatives from readily available substrates under metal‐free and mild conditions in a single step with only water and hydrogen as the by‐products, but also opens the way to the application of o ‐formyl arylisocyanides in the synthesis of nitrogen‐containing heterocycles.