“Walking” of the CC π Bond over Long Distances in Pd‐Catalyzed Reactions of 2,3‐Allenoic Acids with ω‐1‐Alkenyl Halides

Taking the bond for a walk: An ω-1-alkenyl group was introduced at the β position of butenolides by the PdII-catalyzed coupling/cyclization of 2,3-allenoic acids with ω-1-alkenyl halides (see scheme). The active PdII catalyst was regenerated through the combination of cyclic oxypalladation–carbopalladation with repeated dehydropalladation/hydropalladation–dehalopalladation.