Concise synthesis of the angular dihydrofuroquinoline alkaloids via cyclopropane opening in the presence of polyphosphoric acid

Abstract We report a concise method for synthesis of dihydrofuroquinolinone alkaloids, in which the cyclopropane opening and closure was the key step. The only angluar type product was obtained in fairly high yields. IR, UV, 1H NMR, 13C NMR, and MS were used to confirm the structure. A possible mechanism in also described.