Fluoro-a,p-unsaturated carboxylic acids

The zinc procedure has been extended to CF3CCI3 to form 2 chloro-l,l,l,-trifluoro-2-alkenes (84 equation 19). and a-fluoro-a,p-unsaturated carboxylic acid methyl esters (87) with methyl dichlorofluo-roacetate (8jS equation 20). Both of these transformations are carried out with zinc and acetic anhydride. Several variations of this reaction have appeared in the literature." The mechanism appears to dramatically different from the Oshima methylenation. In this case, the reaction proceeds through the alcohol intermediate, which is converted to the acetate and reductively cleaved. 

Allmendinger, T. (1991) Ethyl phenylsulfinyl fluoroacetate, a new and versatile reagent for the preparation of a-fluoro-a,P-unsaturated carboxylic acid esters. Tetrahedron, 47, 4905-4914. 

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See also in sourсe #XX -- [ ]

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