Nickel-catalyzed reaction of iododifluoroacetates with alkenes and zinc: a novel and practical route to alpha,alpha-difluoro-functionalized esters and alpha,alpha,omega,omega-tetrafluoro diesters

The nickel-catalyzed reactions of iodofluoroacetates (ICF2CO2R) with alkenes and zinc in tetrahydrofuran produce alpha,alpha-difluoro esters in 60-83% yields. In the case of dienes, the product depends on the chain length and the alkene/haloester ratio. With 1, 8-nonadiene and 1,5-hexadiene, two equivalents of ICF2CO2Et produce alpha, alpha,omeega,omega-tetrafluoro esters. With 1,6-heptadiene, 1/2 equivalent of ICF2CO2Et gives a mix of ethyl 2,2-difluoro-8-nonenoate and a cylopentyl-substituted alpha,alpha-difluoro ester. The inhibiting action of p-nitrobenzene and hydroquinone on the reactions supports a one-electron transfer mechanism.