Phosphine-Catalyzed Vinylation at Low Acetylene Pressure
Nikolai A. Sitte, Maximilian Menche, Pavel Tužina, Frank Bienewald, Ansgar Schäfer, Peter Comba, Frank Röminger, A. Stephen K. Hashmi, Thomas Schaub
Abstract
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.