Silicon Reagent with Functionalized Tetrafluoroethylene Fragments: Preparation and Coupling with Aldehydes

A new fluorinated silicon reagent bearing a functionalized tetrafluoroethylene fragment was prepared from two CF 2 building blocks: ethyl bromodifluoroacetate and (bromodifluoromethyl)trimethylsilane. The key C–C bond-forming step involves a difluorocarbene addition/cyclopropane rearrangement sequence. The silicon reagent was coupled with aldehydes and reactive azomethines in the presence of potassium fluoride.