The a,@-butenolide substructure is found in a wide variety of natural products including many flavor components and insect pheromones." In addition, compounds incorporating functionalized a, &butenolides, or their derivatives, have been shown to be biologically active and some display antitumor activity. lb Although approaches to the syntheais of a#- butenolides have been diverse they can be classified ae either elaboration of an existing ...