AbstractAttempted epoxidation of long‐chain α,β‐unsaturated esters resulted in the formation of the rearranged products of the corresponding epoxyesters. It was observed that reaction of peracids with esters of C16, C18and C22trans‐2‐enoic acids, instead of yielding the expected epoxides, gave the isomerized products characterized as β‐ketoesters. The structure of β‐ketoester as saturated 3‐oxoester was unambiguously established by chemical methods as well as by IR, NMR and Mass spectrometry. The selectivity of this rearrangement provides a useful synthetic pathway for the preparatio