Several carbon-carbon bond forming reactions useful for organic synthesis are achieved by electrochemical reduction. (1) Electroreduction of ketones in isopropyl alcohol containing a tetraalkylammonium salt generates anion radical species which reacts with aromatic rings, nitriles, and
O-alkyl oximes intra- and intermolecularly. Some ring-fused sesquiterpenes and α, β-disubstituted cyclopentanones such as dihydrojasmone are synthesized by electroreduction of γ-cyano ketones. (2) Electroreduction of a system comprising CX
3Y, CHX
2Y, and an aldehyde leads to an anionic chain reaction and gives the corresponding coupling products, RCH(OH)CX
2Y, in high current efficiencies and yields. The addition of -CCl
2CO
2Me to α-branching aldehydes shows high diastereoselectivity. (3) Electroreduction of aromatic imines in the presence of chlorotrimethylsilane generates anionic species which reacts with electrophiles to give the corresponding inter- and intramolecular cross-coupling products. (4) Electroreduction of aromatic diimines under acidic conditions gives intramolecular coupling products stereoselectively. This reaction is useful for the synthesis of substituted piperazines and 1, 4-diaza-crown ethers.
抄録全体を表示