A new approach to the synthesis of phosphoranes based on the reaction of benzo[d]-1,3,2-dioxaphospholes having a β- or γ-carbonyl group in exocyclic substituent with hexafluoroacetone

The reaction of 2-(2-oxo-1,2-diphenylethoxy)- and 2-(1-methyl-3-oxobut-2-en-1-yloxy)benzo[d]-1,3,2-dioxaphospholes with hexafluoroacetone is a versatile approach to the synthesis of 6,6-bis(trifluoromethyl)-3,4-diphenyl-1,1-phenylenedioxy-1-phospha-2,5,7-trioxabicyclo[2.2.1]heptane and 3,5-dimethyl-7,7-bis(trifluoromethyl)-1,1-phenylenedioxy-1-phospha-2,6,8-trioxabicyclo[2.2.1]oct-3-ene, respectively, in high yields.