Treatment of 1-bromo-2,2-dichloro-3-trimethylsilylcyclopropane with CsF in THF refluxing temperature gave chlorocyclopropenyl cation (1), which reacted with various nucleophiles to generate 3-monosubstituted 1-chlorocyclopropenes. The Diels-Alder reactions of 3-monosubstituted 1-chlorocyclopropenes with 1,3-diphenylisobenzofuran (DPIBF) yielded only the exo-anti adducts in excellent yield. When cation 1 was treated with water and trapped with DPIBF, an aldehyde, 12, was isolated.
Cycloalkenes proceed through bromination, dehydrobromination and dibromocarbene addition reactions to give tribromocyclopropanes 10 and 11. The treatment of tribromocyclopropanes 10 and 11 with 3 equiv. of methyllithium in diethyl ether at -78°C followed by treatment with trimethylsilyl chloride produce 8-(trimethylsilyl)bicyclo[5.1.0]oct-1(8)-ene (4) and 9-(trimethylsilyl)bicyclo[6.1.0]non-1(9)-ene (5). Both 4 and 5 undergo ene dimerization via the same steric isomer and an endo transition state to generate the stable adducts 6
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