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Several aliphatic nitriles, esters, sulfones, and ketones bearing an -o-chlorophenyl substituent react with potassium amide in liquid ammonia to furnish cyclization products in which a homocyclic ring is fused into the benzene ring. Benzocyclobutene, indane, tetralin, and benzocycloheptene derivatives have been prepared, mostly in yields of 50-80%. Aryne intermediates are thought to be involved; this view is supported by the fact that both orthoand meta-4-(chlorophenyl)butanonitrile undergo cyclization to 1-cyanoindane. For preparation of the benzocyclobutene system, this is a method of choice. However, the potentialities for further application of this principle of synthesis have perhaps greater interest than were used to transform the resulting esters or nitriles into structures required for further chainlengthening or for submission to ring closure conditions. Most of the intermediates and the final

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