Preparation of Organocupper Species Using Silyl Migration and Their Application to Organic Synthesis

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In this research, preparation methods of organocupper species using O^<sp2>-to-O silyl migration and applications of their organocopper species to organic synthesis were studied. We found that vinylcopper species were readily prepared from vinylsilanes having a hydroxyl group via the 1,3-and 1,4-Brook-type rearrangement by treatment with copper(I) t-butoxide. It was suggested that these reactions were promoted by the combination of the use of copper(I) alkoxides and the formation of silicates by the intramolecular coordination of the alkoxide group. The vinycopper species reacted with various organic halides even in the presence of a proton source to give coupling products. The present silyl rearrangement is applicable to copper(I) enolates prepared from either α-and β-silyl-α,β-unsaturated ketones and copper(I) t-butoxide to produce the vinylcopper species having enol silyl moiety ; by the reaction of the organocopper species with organic halide, the C-C bond formation was achieved with stereoselective formation of the enol silyl ether.We also demonstrated that allenes were obtained by the Peterson elimination of copper(I) alkoxides of β-triphenylsilylallylic alcohols through the formation of the silicate in the absence of the organic halides. This is the first example of the Peterson elimination at a vinylic position leading to the formation of allenes. The Peterson elimination proceeded even when the β-triphenylsilylallylic alcohols were treated with BuLi by virtue of DMF as a cosolvent. Based on this result, a straightforward carbonyl allenation method was developed by the Pereson olefination of α-lithiovinylsilanes and carbonyl compounds.