The stereospecific preparation of two perfluoro-1,3-butadiene synthons; (E)-1-trimethylsilyl-1,2,3,4,4-pentafluoro-1,3-butadiene and (E)-1-tributylstannyl-1,2,3,4,4-pentafluoro-1,3-butadiene

(E)-1-Trimethylsilyl-1,2,3,4,4-pentafluoro-1,3-butadiene (1) can be stereospecifically prepared by Pd(0)/CuI catalyzed cross-coupling of (Z)-1-tributylstannyl-1,2-difluoro-2-trimethylsilylethene with iodotrifluoroethene. The corresponding (E)-1-tributylstannyl-1,2,3,4,4-pentafluoro-1,3-butadiene can be prepared via the stereospecific conversion of 1 with Bu3SnOSnBu3/KF (catalysis) to the corresponding vinylstannane.