Isoquinolone derivatives via a furan recyclization reaction

A new approach to the synthesis of isoquinolone derivatives has been developed. It is based on the protolytic recyclization of amides of 2-carboxybenzylfurans. It was shown that the reaction proceeds via formation of allylic alcohols of isoquinolone series, which under acidic conditions undergo isomerization into the corresponding ketones. A new condensed heterocyclic system of furo[2′,3′:3,4]cyclohepta[1,2-c]isoquinolin-8(6H)-one has been synthesized.