Tandem reduction + cyclization of ortho-substituted cinnamic esters

Copper-catalyzed cascade reactions of α,β-unsaturated esters with keto esters

“…Copper-catalyzed reductive intermolecular aldolization reactions have been discussed previously [ 17 – 19 ]. Constantino has demonstrated that aldol reactions of enolates with ketones or aldehydes are much faster than the Claisen condensation [ 20 ]. Therefore, it is rationalized that an α,β-unsaturated monoester-derived enolate should react preferentially with the keto group in the keto ester to yield the alkoxide, which further lactonizes with an intramolecular ester group to form the lactone.…”