Mg(OMe)2 promoted allylic isomerization of γ-hydroxy-α,ß-alkenoic esters to synthesize γ-ketone esters.

This work concerns the Mg(OMe)2 promoted allylic isomerization of γ-hydroxy-α,ß-alkenoic esters with TMEDA as an additive. The isomerization proceeded under mild conditions and afforded γ-keto esters in high yield (up to 96%) within 2 h. Both (Z)- and (E)-γ-hydroxy-α,ß-alkenoic esters were tolerated under the reaction conditions. This transformation involves the in situ formation of a dienolate intermediate from the easily accessible γ-hydroxy-α,ß-alkenoic ester. The in situ generated dienolate can react with benzaldehyde and undergo a practical, useful tandem allylic isomerization-Aldol reaction to afford more functionalized compounds.

Enantioselective synthesis of Anomala osakana pheromone and Janus integer pheromone: a flexible approach to chiral gamma-butyrolactones.

The enantioselective synthesis of Anomala osakana pheromone and Janus integer pheromone has been achieved without using any protecting groups. The synthesis involved using an asymmetric alkynylation to obtain gamma-hydroxy-alpha,beta-acetylenic esters with high ee (84%) and yields ( approximately 80%), followed by selective hydrogenation and lactonization in high overall yields (87% and 89%).