2-Diazo-3,3,3-trifluoropropionyl chloride, 1, and the corresponding p-nitrophenyl propionate, 2, were synthesized by Westheimer et al in 1976.  Since then mostly the chloride has been the preferred photoaffinity labeling reagent for enzymes and proteins and more specifically in recent studies on prenylated proteins.  The following abbreviated synthetic scheme (I) to 1 reported by Distefano et al, based on the works by Gilman and Jones followed by Westheimer et al, is clearly indicative of a lengthy and practically difficult preparation with no yield report.

We propose a convenient and shorter  route to synthesis of p-nitrophenyl derivative, 2, by way of converting 3,3,3-trifluoropropionic acid to the corresponding p-nitrophenyl ester followed by its reaction with tosyl azide to afford 2 in satisfactory yield.  The details of our synthesis will be presented.