Summary: Deconjugative protonations, alkylations, and aldol condensations of the dienolates from (2)-Zalkenoates give the corresponding (E)-3-enoate products, whereas dienolates from (E)-Zenoates give mainly the (a-3-enoate products. These generalizations are exploited in stereospecific total syntheses of litsenolides A2, B2, and C2.
