Electrophilic ipso-Halocyclizationof N-Arylpropynamides with Polyfluoro-alkylAlcohols: Selective Synthesis of 8-(Polyfluoroalkoxy)azaspiro[4.5]trienes

A novel and efficient method for the synthesis of 8-(polyfluoroalkoxy)-1-azaspiro[4.5]deca-3,6,9-trien-2-ones has been demonstrated via the electrophilic ipso-halocyclization of N-arylpropynamides with polyfluoroalkyl alcohols. In the presence of N-halosuccinimides (NXS), a variety of N-arylpropynamides underwent an electrophilic ipso-halocyclization reaction with polyfluoroalkyl alcohols to afford the corresponding 8-(polyfluoroalkoxy)spiro[4.5]trienes in good yields. Note that molecular sieves can improve the yield of the reaction.