Reinvestigation of the synthesis of 3-dimethylallyl-4-hydroxy-2-quinolones. A novel route to tetracyclic heteroaromatic compounds

Abstract

The reaction of diethyl 2-(3-methylbut-2-enyl)malonate with a variety of anilines has been used in the past as a method of alkaloid synthesis. It has now been found that this reaction yields, in addition to the expected 3-di methylallyl-4-hydroxy-2-quinolones, 3,3′-methylenebis -4-hydroxy-2-quinolones, and dibenzo[b,h][1,6]naphthyridin-6(5H)-ones. A mechanism is suggested to explain this unusual reaction.