The chemistry of cycloheptatriene: Part I. Synthesis of benzocyclobutene

Addition of dichlorocarbene to cyclopentadiene yields chlorobenzene. The addition of dichlorocarbene to cycloheptatriene yields 8,8‐dichloro‐bicyclo [5.1.0] octadiene‐2,4 (II). When (II) is heated at 140° a rearrangement to 1‐chlorobenzocyclobutene (III) occurs with evolution of HCl. Reduction of (III) with hydrogen in the presence of palladium gives benzocyclobutene (V).