Kiyoshi Ukawa

Studies on antianaphylactic agents—III : A novel conversion reaction of 4-oxo-4H-1-benzopyran-3-carboxaldehydes to 3-halogenochromones

Abstract 4-Oxo-4H-1-benzopyran-3-carboxaldehydes in acetic acid react with sodium hypochlorite (aqueous solution) to yield 3-chlorochromones. The reaction of sodium hypobromite with 1 yields 3-bromochromone 15 and other compounds depending on the conditions. Under the normal laboratory lighting hydroxyacetophenone 14, 15 and hydroxychromanone 16 were obtained, whereas 15 and acetoxychromanone 17 were produced by the reaction in the dark. The addition-elimination mechanism described is the most likely in these reactions.