Umlagerungsreaktionen von Cumarinen als Folge einer intermediären Öffnung des Lactonringes / Rearrangements of Coumarins, Caused by an Intermediate Cleavage of the Lactone

Abstract

The condensation of 2-hydroxy-1-naphthaldehyde with ethyl cyanoacetate is investigated. Rearrangement for the obtained naphthopyranyl-ethyl-cyanoacetate (5) is reported, yielding 5,6-benzocoumarin-carbonitrile and naphthopyranyl-aminoacrylate (6). Enamine-lactone-rearrangement of 6 leads to chromene-carboxylic acid (7). By hydrolysis of the benzopyranyl-ethyl-cyanoacetate (8) and addition of cyanoaceticacid derivatives to 3-cyanocoumarin or 3-carboxyamido-coumarin resp., the benzopyrano-pyridines 12 are obtained.