The reaction of phenylglyoxal with 2, 4-pentanedione in the presence of boron trifluoride gave the unstable 3-acetyl-1-phenyl-2-pentene-1, 4-dione intermediate which was converted in situ by the reaction with an excess amount of 2, 4-pentanedione into new crystalline tri-and tetra-substituted furans. Other unstable 1-aryl-2-pentene-1, 4-diones, which were obtained by the photooxygenation of 3-acetyl-5-aryl-2-methylfurans, were ...
