Enantioselective Formal C(sp2 )-H Vinylation.

An enantioselective formal C(sp2 )-H vinylation of prochiral 2,2-disubstituted cyclopentene-1,3-dione is presented. This vinylative desymmetrization is realized by using a two-step procedure that consists of a catalytic enantioselective vinylogous Michael addition of deconjugated butenolides to cyclopentene-1,3-dione and a base-mediated decarboxylation. The overall process utilizes deconjugated butenolides as the source of the highly substituted vinyl unit. Five-membered carbocycles containing a remote all-carbon quaternary stereogenic center are obtained in good yields and with good to high enantioselectivities.