Pd(II)-catalyzed coupling cyclization of 2,3-allenoic acids with allylic halides.: An efficient methodology for the synthesis of β-allylic butenolides

An effective method for the synthesis of beta-allyl polysubstituted butenolides from the easily available allylic halides and 2,3-allenoic acids is described. By using this method optically active butenolides can be obtained. According to the results presented in this paper, the reaction may proceed via three consecutive steps: cyclic oxypalladation of the allene, insertion of the C=C bond in allylic halides, and beta-dehalopalladation.