Iron-catalyzed asymmetric intramolecular cyclopropanation reactions using chiral tetramethyl-1,1'-spirobiindane-based bisoxazoline (TMSI-BOX) ligands

摘要

The versatile application of chiral bisoxazoline (BOX) ligands in diverse metal-catalyzed asymmetric reactions results in growing demand for novel BOX ligands containing different motifs. Herein, the successful development of a chiral spiro bisoxazoline ligand (TMSI-BOX) on the basis of the tetramethyl-1,1'-spirobiindane motif and bisoxazoline chelating units is described. The corresponding Fe complexes of TMSI-BOX proved to be excellent catalysts in the asymmetric intramolecular cyclopropanation reaction of diazo derivatives, providing synthetically versatile [3.1.0]bicycloalkane derivatives bearing two contiguous quaternary chiral centers with high enantiomeric purity.