Interaction of O- and P- nucleophiles with perfluorinated olefins: Novel synthetic route to fluorinated phosphorus-containing monomers

Abstract

A novel synthetic method for the preparation of partially fluorinated unsaturated diethyl phosphonates and phosphonic acids is presented involving the deprotonation of the starting α-hydroxymethyl diethylphosphonate or diethylphosphite with a strong base, followed by in situ addition of an O- or P-nucleophile to the terminal double bond of the perfluorinated olefin. Subsequent elimination of the corresponding leaving groups and restoring of the double bond leads to the target bifunctional perfluorinated olefins. Reaction of the diethyl phosphonate group with trimethylsilyl bromide (TMS-Br) and subsequent hydrolysis/methanolysis gave the corresponding unsaturated phosphonic acids. In the case of using α-hydroxymethyl diethylphosphonate, the reaction may be accompanied by an addition of a second equivalent of an O-nucleophile to form bis-functional internal olefins. The reaction conditions, factors affecting the reactivity, stereo- and regioselectivity of the process, the choice of reagent as well as the course of competitive reactions are discussed, too.