Continuous flow asymmetric cyclopropanation reactions using Cu(I) complexes of Pc-L-star ligands supported on silica as catalysts with carbon dioxide as a carrier

Continuous flow heterogeneous asymmetric cyclopropanations catalysed by supported hydrogen-bonded (SHB) chiral copper(I) complexes of pyridine containing tetraazamacrocyclic ligands Pc-L-star using CO2 as a transport vector are described. The catalytic system showed high stability and good recyclability without loss of activity for at least 24 h in CO2 and catalyst turnover numbers up to 440 were obtained with excellent conversion (up to 99%) and high selectivity (up to 88%). No leaching of copper was observed. Cyclopropane products from both aromatic and aliphatic olefins were obtained in good yields with enantiomeric excesses up to 72%.