Synthesis of 1,1-Difluoro-1-Alkenes from Aldehydes and Ketones by a modified wittig reaction

Abstract

The reaction of tertiary phosphines with dibromodifluoromethane provided a rapid and high yield synthesis of various type of fluorinated phosphonium salts. These salts were useful precursors to fluorine-containing ylides, carbenes and methide ions. The reaction of bromodifluoromethyl triphenylphosphonium bromide and triphenylphosphine with aromatic aldehydes gave 1,1-defluoroolefins in glyme. The reaction of bromodifluoromethyl $tris$-dimethylaminophosphonium bromide and $tris$-dimethylamioposphine with nonactivated ketone gave 1,1-difluoroolefin in glyme solution. The structures of these products were characterized by IR, $^1HNMR$, and $^{19}F$-NMR spectroscopy.