The photocycloaddition reaction of 5-phenylfuran-2,3-dione (1) to phenylethylene proceeded in a [2+2] manner with regio- and stereo-selectivities to give 2-oxabicyclo[3.2.0]heptane-3,4-diones with 7-endo-phenyl as a major adduct (3) and 7-exo-phenyl stereochemistries as a minor one (4). The reaction demonstrated that dioxofuran is a useful synthon for synthesis of substituted cyclobutane derivatives.