DBU-mediated Ireland-Claisen rearrangement of allyl alk-3-enoates: an efficient synthesis of 2-ethylidene-γ,δ-unsaturated carboxylic acids

Ireland-Claisen rearrangement, triggered by silyl enolization of allylic but-3-enoates 2, was achieved using DBU as the base in the presence of an excess amount of TMSCl to provide 2-ethylidene-γ,δ-unsaturated carboxylic acids 5 in good yields.