(±)-Stemoamide (1) was prepared in seven steps beginning with γ-chlorobutryl chloride (20) and succinimide (15), which were efficiently converted to the key alkyne oxazole 17 on a multigram scale. Intramolecular (Diels−Alder)−(retro-Diels−Alder) reaction of 17 then gave butenolide 12b directly upon aqueous workup. The remaining two stereocenters in 1 were established in a single step by a highly selective