Phosphine-Catalyzed Vinylation at Low Acetylene Pressure

The vinylation of
various nucleophiles with acetylene at a maximum
pressure of 1.5 bar is achieved by organocatalysis with easily accessible
phosphines like tri-n-butylphosphine. A detailed
mechanistic investigation by quantum-chemical and experimental methods
supports a nucleophilic activation of acetylene by the phosphine catalyst.
At 140 °C and typically 5 mol % catalyst loading, cyclic amides,
oxazolidinones, ureas, unsaturated cyclic amines, and alcohols were
successfully vinylated. Furthermore, the in situ generation of a vinyl
phosphonium species can also be utilized in Wittig-type functionalization
of aldehydes.