Introduction of Different Groups to α- and β-Positions of Cyclic α,β-Unsaturated Ketones via [2π + 2π] Photocycloaddition with Ketene Silyl Acetals Followed by Electrode Reaction
acetylenedicarboxylate is reacted with ketene alkyl trimethylsilyl acetals in the presence of a catalytic amount of zirconiumtetrachloride, dimethyl 2-alkoxycarbonyl-3-alkylidenebutanedioates are afforded. Although the silyl enol ether from acetophenone undergoes the same type of reaction, other trisubstituted silyl enol ethers such as those from butyrophenone and 3-pentanone fail to react with dimethyl