A Facile and Convenient Synthesis of Trisubstituted (E)-α,β-Unsaturated Esters by Tandem Acetylation-E1cB Reaction.

A facile and convenient synthesis of trisubstituted (E)-alpha,beta-unsaturated esters was developed by improving our previously established method. The new method circumvented the separation of the intermediates, which have an activating group of the hydroxyl group in beta-hydroxy esters, furnishing alpha,beta-unsaturated esters in shorter steps than the previous method: an acetylation of beta-hydroxy group and subsequent E1cB reaction proceeded in tandem. In addition, the new method can not only employ a diastereomeric mixture of the substrate for the E1cB reaction, it has a wide substrate scope as well, which would enable the synthesis of various trisubstituted (E)-alpha,beta-unsaturated esters.