Stereospecific Synthesis of (Z)-α-Fluoro-β-trifluoromethyl Vinyl Iodides and Their Application to the Synthesis of Polyfluorinated Thienyl Alkadienes^†

The direct iodination of polyfluorinated vinyl stannanes by tin-iodine exchange methodology was achieved giving(Z)-α-fluoro-β-trifluoromethyl vinyl iodides stereospecifically. Changing the substituent in R group from the electron-withdrawing group to electron-donating group led to an increase in the yield from 78% to 90%, while it was moved from para to meta position the reaction did not afford a dramatic change in the yield (90% to 95%). In addition, this reaction also can be applied to the vinyl stannane with heterocyclic group. The further coupling reaction of prepared vinyl iodide containing heterocyclic moiety with (Z)-α-fluoro-β-trifluoromethylstannanes gave polyfluorinated heterocyclic alkadienes with 2E,4E-selectivity.