Gas-Phase Reactions of 1,2-Dimethylcyclopentene and of 2,6-Heptanedione with Ozone: Unprecedented Formation of an Ozonide by Ozone Treatment of a Diketone

Gas-phase ozonizations of 1,2-dimethylcyclopentene (1) and of 2,6-heptanedione (5) afforded in each case dimethylcyclopentene ozonide (2) in low yields. In the ozonization of 1, diketone 5 was formed as the single major product, along with nine “abnormal” ozonolysis products which were formed by oxidative cleavage of carbon−carbon single bonds.