The synthesis of spiro[bicyclo[2.2.1]heptene-7,1′-cycloalkan]-2′-ones and related benzobicyclo[2.2.1]heptene derivatives

Publisher Website
Google Scholar
Abstract
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.

This publication has 0 references indexed in Scilit: