Catalytic Allylations of Carbonyl Compounds Enabled by In Situ-Generated Allylzinc Species through the Silylzincation of 1,2-Dienes

Organozinc compounds are frequently used as mild carbon-based nucleophiles to form carbon−carbon bonds in synthetic organic chemistry owing to their moderate reactivities and chemoselectivities. However, they generally require stoichiometric amounts. Herein, we report the Zn-catalyzed allylations of carbonyl compounds via a β-silylallylzinc intermediate that is catalytically generated from a 1,2-diene, a silylborane, and a Zn complex. A variety of aldehydes react to afford five-membered cyclic silyl ethers bearing a vinylsilyl moiety in good yields. The reaction products contain versatile C(sp 2 )-Si bonds that can be effectively converted into C−C or C−O bonds. The regioselectivity is controlled by the steric bulk of electrophiles, yielding homoallylic alcohols with ketones.