3-oxobutanamides underwent manganese(III)-mediated oxidative intramolecular addition to produce dihydrofuran-fused macrolides and macrocyclic amides from 8 to 26 members. A similar reaction of the oligooxamethylene-tethered ω-alkenyl 3-oxobutanoates also gave dihydrofuran-fused crown ether type macrolides which had a phase-transfer ability with sodium and potassium picrates. The manganese(III)-assisted specific