Selektive Cyclotetramerisierung von Propargylalkohol: katalytische Reaktionen hoher Selektivität und Geschwindigkeit an Nickelkomplexen

Selective Cyclotetramerization of Propargylic Alcohol: Catalytic Reactions with High Selectivity and Reaction Rate by Nickel Complexes It is shown propargylic alcohol reacts with different nickel catalysts to form cyclotetrameres in a selective reaction. Main product of the reaction is 1,3,5,7-tetrakis(hydroxymethyl)-cycloocta(1,3,5,7)-tetraene. The reaction is extremely fast; when it is carried out without solvents at 114°C turnover numbers of 10⁶ catalytic cycles/mol Ni × h can be observed. The influence of phosphines is different: In solvents aromatic compounds, and cyclotetrameres are formed, when solvents are not used, phosphines have no controlling effect. The reaction can also be catalyzed by iron complexes to form cyclotetrameres, cobalt complexes yield a mixture of cyclotrimeres and cyclotetrameres. Supported Nickel or Raney-Nickel can also catalyze the cyclotetramerization. The investigations show that the 1-azadiene ligands in bis(cinnemaldehydeanil)-nickel(0) are substituted by propargylic alcohol in a fast reaction. After the substitution the catalytic reaction takes place at “ligand free nickel”.