Cyclopenten-3, 4, 5-triones having phenyl, methoxy, and dialkylamino groups at their olefinic double bonds were synthesized, and their structural properties were discussed from their infrared and ultraviolet spectra, and pk values. It is proposed that delocali-zability of electron system of the ring is greatly affected by the electron donating ability of the substituent, and that the ring system having strong electron donating groups has a kind of ...
