Pre-electrolysis of LiClO4 in Acetonitrile: Electrochemically Induced Protolytic Carbon-Carbon Bond Formation of Benzylic Ethers and Acetals with Allyl Trimethylsilane and Other Carbon Nucleophiles

The pre-electrolysis of LiClO4 in acetonitrilein anundivided cell applying only "catalytic" amounts ofcurrent (e.g., 0.05 F) led to the formation of a strong acidic mediumfor the activation of benzylic ethers and acetals. The activated primaryand secondary benzylic ethers and acetals could be converted witha range of carbon nucleophiles, such as allyl trimethylsilane, silylenol ethers, and enol acetates, for the formation of new carbon-carbonbonds. A chemoselective reaction was observed when electron-deficientbenzylic acetals were converted with allyl trimethylsilane to themonoallylated products, whereas an electron-rich benzylic acetal ledto the double allylated product under activation of both ether groups.