Benzocyclobutenes. Part 9. Synthesis of bromo-, chloro-, and oxo-derivatives of benzocyclobutene and naphtho[b]cyclobutene

Addition of benzyne to 1,1-dichloro- and 1,1,2-trichloro-ethene gave the corresponding di-(61%) and tri-(18%) chloro derivatives of benzo-cyclobutene. Similarly 2,3-didehydronaphthalene and 1,1-dichloroethene gave 1,1-dichloronaphtho[b]cyclobutene. Some reactions, including reduction, chlorination, bromination, and hydrolysis of these cyclobutenes and of related compounds are described.