Zn(OTf)2 catalyzed addition–cyclization reaction of allenylphosphine oxides with propargyl alcohol-unexpected formation of 2,5-dimethylenetetrahydrofurans and 2-substituted furans

A novel synthesis of 2,5-dimethylenetetrahydrofurans, 2-substituted furans and a β,ω-diketophosphonate in good to excellent yields has been achieved by the reaction of allenylphosphine oxides/allenylphosphonate with propargyl alcohol using zinc triflate/triethylamine combination.