Stereospecific Synthesis of (+)- and (−)-Cyclooctenone Derivatives Using a Ring Expansion Reaction with Me3SiSnBu3 and CsF

Novel synthesis of an eight-membered compound by the ring expansion reaction of a two-carbon unit was developed using the stannyl anion generated from Me 3 SiSnBu 3 and CsF in DMF. cis - and trans -cyclooctenone derivatives were synthesized from cyclohexanone derivatives having vinyl iodide in a tether by treatment with Me 3 SiSnBu 3 and CsF in DMF in a stereospecific manner. The trans -cyclooctenone derivative was isomerized to the cis -isomer in the presence of Me 3 SiSnBu 3 and CsF. It is known that the trans -eight-membered ring is an asymmetric compound. Using this procedure, (+)- and (−)- trans -cyclooctenone derivatives could be synthesized from the corresponding optically active cyclohexanone derivatives.