corresponding 2(5H)-furanones or 2(3H)fiiranones, depending on the substitution and reaction conditions, is described here. Butenolides are unsaturated γ-lactones which may be also regarded as 2(3H)furanones 1 or 2(5H)-furanones 2. The 2(5H)-furanone ring occurs widely in nature but we found no isolated natural products containing the 2(3H)-furanone core. This is probably because the 2(5H)-furanones are more