Stereoselective Syntheses of γ,δ-Bifunctionalized Homoallylic Alcohols and Ethers via Chemoselective Allyl Addition to Aldehydes.

Stereoselective synthesis of γ,δ-bifunctionalized homoallylic alcohols and ethers via chemoselective allylation is reported. Pd-catalyzed 1,2-diboration of allenylsilane provided a novel 1,1,2-trifunctional allylation reagent. Allylboration of aldehydes with the reagent followed by protection gave TES-protected homoallylic alcohols with excellent -selectivities. Chemoselective allylsilation with the same reagent delivered γ,δ-bifunctionalized homoallylic ethers with high -selectivities. The bifunctionalized alkene group in the products underwent various transformations without erosion of the olefin geometry.