A selective oxidative fission of the heterocyclic nucleus of 5-methyl-2-(acylmethyl)furans or 2-(5-methyl-2-furyl)-1,3-dicarbonylcompounds by m-chloroperbenzoic acid allows the easy synthesis of the 3(2H)-furanone system.
Photo-sensitized oxygenation of the furyl diketones (1) affords furan-3(2H)-ones (3) in satisfactory yields, presumably via the intermediate open-chain enetriones (2).