Abstract 1, 1, 1, 3, 3-Pentafluoropropane-2-one (3)(pentafluoroacetone) is readily obtained from 1, 1, 1, 3, 3, 3-hexafluoropropane-2-ol by dehydrofluorination using lithium bis (trimethylsilyl) amide, followed by isomerization of 1, 1, 3, 3, 3-penta-fluoropropene-2-ol. Pentafluoroacetone adds trimethylsilylphosphites to yield α-trimethylsiloxyphosphonates which, upon thermolysis, furnish (Z)-1, 3, 3, 3-tetrafluoropropenyldialkylphosphites and (Z) ...