Stability of Medium-Ring Cyclic Unsaturated Carbonyl Compounds: Direct Access to Unsaturated Ketones with C–C Double Bonds at Distal Positions via Transfer Dehydrogenation of Alicyclic Ketones

Medium-ring cyclic compounds have characteristic distortions.
For
alicyclic enones, conjugated enones are known to be less stable than
unconjugated enones. In this study, the relative stability of cycloalkenones
with varied C–C double bond positions with C6–C12 rings
was theoretically investigated to reveal that C8–C12 cycloalkenones
prefer the unconjugated isomer. Furthermore, direct access to distal
unsaturated cycloalkenones has been accomplished by transfer dehydrogenation
of cycloalkanones catalyzed by iridium complexes.