Rhenium-catalyzed insertion of nonpolar and polar unsaturated molecules into an olefinic C-H bond

Treatment of olefins bearing a directing group with α,β- unsaturated carbonyl compounds, alkynes, or aldehydes in the presence of a catalytic amount of a rhenium complex, [ReBr(CO)₃(thf)]₂ gave γ,δ-unsaturated carbonyl compounds, dienes, and allyl silyl ethers, respectively. This reaction proceeds via C-H bond activation, insertion of unsaturated molecules into the formed rhenium-carbon bond, and then reductive elimination (or transmetalation in the case of aldehydes).