Generation of Oxyallyl Cations by Reduction of α,α′-Diiodoketones Under Sonochemical or Thermal Conditions: Improved Methodology for the [4C(4π;)+3C(2π;)] Cycloaddition Reactions

Abstract An improved methodology to carry out [4C(4π;)+3C(2π;)] cycloaddition reactions of dienes and oxyallyl cations, is presented. The reaction starts from commercially available dienes and easy-handling α,α′-diiodoketones, which are reduced by Zn (powder) or Zn/Cu couple to generate an oxyallyl cation as an intermediate. The reaction is carried out under mild thermal or sonochemical conditions at low temperatures (from 0 to −44°C) and for short reaction times (<15 min).