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

Stereoselective synthesis of ykbifunctionalized 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 in situ protection gave TES -protected homoallylic alcohols with excellent Z-selectivities. Chemoselective allylsilation with the same reagent delivered y,(5-bifunctionalized homoallylic ethers with high E-selectivities. The bifunctionalized alkene group in the products underwent various transformations without erosion of the olefin geometry.