Acid-catalyzed rearrangements of some 1,6-diketones

2-(4-Ketoalkyl)cyclopentanones, when subjected to the action of 1 M H2SO4 at reflux, undergo ring cleavage and formation reactions to give 4-(1-cyclopentenyl)butanoic acids. When the starting ring is six-membered instead, a bicyclic enone results. Mechanistic discussion and some experimental tests are put forth.