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

Abstract

Continuous flow heterogeneous asymmetric cyclopropanations catalysed by supported hydrogen-bonded (SHB) chiral copper(I) complexes of pyridine containing tetraazamacrocyclic ligands Pc-L* 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%.