7-Norbornenone gives on treatment with diphenylsulfonium cyclopropylide an epoxide that rearranges thermally to a mixture of syn- and anti-spiro[bicyclo[2.2.1]heptene-7,1′-cyclobutan]-2′-ones. Treatment of 7-norbornenone with cyclobutylidenetriphenylphosphorane gives 7-cyclobutylidenenorbornene, which on epoxidation and rearrangement gives syn-spiro[bicyclo[2.2.1]heptene-7,1′-cyclopentan]-2′-one. This is also formed on treatment of syn-spiro[bicyclo[2.2.1]heptene-7,1′-cyclobutan]-2′-one with tert-butyl diazoacetate and triethyloxonium fluoborate followed by decarboalkoxylation. Similar homologation of anti-spiro[bicyclo[2.2.1]-heptene-7,1′-cyclobutan]-2′-one affords anti-spiro[bicyclo[2.2.1]heptene-7,1′-cyclopentan]-2′-one. 7-Isopropylidenebenzonorbornene with acetyl chloride and aluminum chloride gives 7-syn-acetyl-7-anti-isopropenylbenzonorbornene, which on dibromination followed by condensation with isopropylidene malonate gives a dispiro ketone related to these spiro ketones. The structures of the spiro compounds have been established by infrared and nuclear magnetic resonance spectroscopy and by studies of their reactions.
tert.-Butylation of Toluene: A Statistical Study