A novel synthesis of functionalized gem-difluoro-penta-1,4-dienes

The 2,2-difluoro-1-tosyloxyvinyl anion 2, generated from the 2,2,2-trifluoroethyl p-toluenesulfonate 1 and 2 eq of n-butyllithium, reacted with α-ethoxycarbonyl vinylphosphonate 3 to give the phosphoryl-stabilized carbanion 4 which reacted further with a variety of aldehydes affording functionalized gem-difluoro-penta-1,4-dienes in 69–96% yields.