Widman-Stoermer Synthesis

The synthesis of cinnoline derivatives by means of the diazotization of o ‐aminostyrenes with sodium nitrite and hydrochloric acid is known as the Widman–Stoermer synthesis. In general, the Widman–Stoermer reaction is difficult to occur when an aryl group or an electron‐withdrawing group is present on the β‐position of styrene; in contrast, the presence of a simple electron‐donating group such as methyl or ethyl facilitates the cyclization. This reaction is useful for the preparation of cinnoline derivatives.