Diethyl bromodifluoromethylphosphonate

Dialkoxyphosphinydifluoromethyl cadmium reagent can be readily prepared via reaction of diethyl bromodifluoromethylphosphonate with acid-washed cadmium powder [270] (Scheme 93). This cadmium reagent exhibits remarkable stability and versatile chemical reactivity. Typical examples are outlined below [271-273] (Scheme 93). 

Diethyl bromodifluoromethylphosphonate may be prepared according to the literature procedure. 1 See Protocol 1. 

Waschbiisch, R., Samadi, M., and Savignac, P, A useful magnesium reagent for the preparation of l,l-difluoro-2-hydroxyphosphonates from diethyl bromodifluoromethylphosphonate via a metal-halo-gen exchange reaction, J. Organomet. Chem., 529, 267, 1997. 

Hu, C.-M.. and Chen.. 1., Addition of diethyl bromodifluoromethylphosphonate to various alkenes initiated by Co(lll)/Zn bimetal redox system, J. Chem. Soc., Perkin Trans. 1, 3T1, 1993. 

The method of converting vinyl to carbonyl groups by ozonolysis has received much attention and has been successfully applied to a variety of phosphonates containing homoallyl groups, including oc-functionalized phosphonates. The homoallyl group is introduced by the reaction of allyl-bromide with diethyl 1-lithioalkylphosphonates. - A convenient preparation of diethyl 1,1-difluoro-2-formylethylphosphonate (Scheme 5.28) involves the ozonolysis of diethyl l-allyl-1,1-difluoromethylphosphonate, which, in turn, is prepared from diethyl bromodifluoromethylphosphonate in 62% yield by treatment of its cadmium bromide derivative with allyl bromide. ... 

The addition of trilialomethylphosphonates to Michael acceptors has also been reported. Thus, in the presence of the cobaloxime(III)/Zn redox system, diethyl bromodifluoromethylphosphonate adds smoothly to acrylonitrile in EtOH to give the 1 1 Michael adduct in 67% yield. Similarly, the copper(I)-catalyzed addition of diethyl trichloromethylphosphonate to methacrylonitrile gives the Michael adduct in modest yield (31%). ... 

Diethyl bromodifluoromethylphosphonate represents an alternative car-bene precursor capable of the mild transformation of alcohols and thiols to their CF2H appended derivatives. In this instance, the carbene is generated by hydrolysis of the phosphate followed by elimination of bromide, which then inserts into the YH (Y = O or S) bond and protonates courtesy of water. Generally, this method requires two equivalents of the carbene precursor and affords good to excellent yields (Scheme 15.88). 

Scheme 15.88 Diethyl bromodifluoromethylphosphonate as a difluorocarbene carbene precursor.

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