The synthesis of pyridine derivatives from 3‐formylchromone

Abstract 3‐Formylchromone (1) reacts with active methylene derivatives to yield condensation products2a‐d, 10,11and12. Treatment of2a‐dwith ammonia or methylamine gives pyridines3–6. Alternatively, reaction of1with enamine derivatives yields pyrido compounds15, 17, 19, 21, 23and28in one step. Factors determining the formation and regiospecificity of the pyridine ring forming reactions are also discussed.