Stereoselective Preparation of Enol Silyl Ethers via Formation of Vinylcopper Species by Silyl Migration

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In the present research, a mew synthetic methodology using multi-component coupling has been developed for stereoselective preparation of enol sily ethers. The process is based on the formation of vinyl copper species by the Brook-type silly migration from sp2 carbon to enolate oxygen as a key reaction. The stereochemistry of the enol silly ethers thus formed is controlled by the formation of the cyclic silicate intermediates. Thus, it was found that the three-component coupling of alpha, beta-unsaturated acylsilanes, the Gilman reagents (or the Grignard reagents / t-BuOCu), and organic halides produced disubstituted enol silyl ethers stereoselectively. The present method is different in concept to conventional methods which rely on stereoselective formation of enolates by deprotonation of ketones.