An Efficient Synthesis of Bibutenolides from 2,3-Allenoic Acids

Significance

A new catalytic system for the preparation of dibutenolides by a cyclization-coupling reaction of 2,3-allenoic acids is described. Three different catalytic systems involving Pd(II) and corresponding additives have been developed, in which the key step is the regeneration of the Pd(II) species to complete the catalytic cycle. The bicyclization reaction gives excellent yields and diastereoselectivity using optically active 2,3-allenoic acids.