Highly stereoselective approach to 3-fluoroalkylated (E)-hex-3-ene-1,5-diyne derivatives via an addition–elimination reaction

Palladium(0)-catalyzed Sonogashira cross-coupling reaction of 2-fluoroalkylated (Z)-2-fluoro-1-iodoethene, which is easily prepared from commercially available polyfluorinated alcohols in facile three steps, with terminal alkynes in DMF at room temperature for 24 h took place stereospecifically to give the corresponding 1-fluoroalkylated (Z)-1-fluorobut-1-en-3-yne derivatives in good to excellent yield. Thus obtained fluoroalkylated 1-fluoroenynes were effectively subjected to addition–elimination reaction with various alkynyllithiums at room temperature, leading to 3-fluoroalkylated hex-3-ene-1,5-diyne derivatives in good to high yields with an excellent E selectivity.