An Efficient Synthesis of 4-Halo-5-hydroxyfuran-2(5<i>H</i>)-ones via the Sequential Halolactonization and γ-Hydroxylation of 4-Aryl-2,3-alkadienoic Acids

4-Halo-5-hydroxyfuran-2(5H)-ones were synthesized via the efficient sequential halolactonization−hydroxylation reaction of 4-aryl-2,3-allenoic acids with I2 or CuX2 (X = Br or Cl) in moderate to good yields. The structures of the products were established by the X-ray single-crystal diffraction study of 3-methyl-4-iodo-5-phenyl-5-hydroxyl-2(5H)-furanone (2a). A rationale for this reaction was discussed based on some brief mechanistic study.