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Alpha,beta-unsaturated delta-lactones from copper-catalyzed asymmetric vinylogous Mukaiyama reactions of aldehydes: scope and mechanistic insights.

A direct regio-, diastereo-, and enantiocontrolled access to alpha,beta-unsaturated delta-lactones is described, based on the reaction of a silyl dienolate and an aldehyde in the presence of 10 % of Carreira's catalyst. The scope and limitations of this reaction, as well as mechanistic insights concerning the reactivity of an allyl copper species, are discussed.