acter of the carbonyl groups, as well as upon other influences which are discussed later. After some trial experiments it was found that keto-(or enol)-lactone V could be cyclized by means of polyphosphoric acid3 at 85". The reaction was slow and appeared to be accompanied by decomposition. A crystalline, neutral compound,'21,-Hzo04, mp 155-156", was obtained in 14% yield. This product was the expected benzsuberene lactone VII, as ...