The general synthesis and trapping of 3-substituted 1-chlorocyclopropenes.

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.