ORGANOCOPPER-IODOSILANE COMBINATIONS IN CONJUGATE ADDITIONS

Article abstract of DOI:10.1016/0040-4020(89)80081-X

This paper concerns new possibilities opened by the addition of (mono)organocopper compounds and iodotrimethylsilane (TMSI) to α,β-unsaturated ketones and esters giving the silyl enol ethers and ketene acetals, respectively.We demonstrate the homogeneous addition of methylcopper-tributyl-phosphine-iodotrimethylsilane to methyl cinnamate, the use of organocopper-bromotrimethylsilane combinations, the dominating formation of Z-silyl enol ethers on conjugate addition of methyl- and butylcopper/TMSI to benzalacetone, and the formation of silyl enol ethers in other additions of organocopper compounds and TMSX to conjugated ketones.The Z-selectivity for addition to benzalacetone corresponds to s-cis conformations in ?-complexes between copper(I) chloride and 1-penten-3-one or 3-buten-2-one.The stereoselectivity could support a reaction path via ?-complexes between organocopper-iodotrimethylsilane complexes and s-cis conformers of the substrates.