Synthesis of Hexamethyl-1,1′-spirobiindane-Based Chiral Spiro Cp Ligands and Their Application in Rhodium-Catalyzed Enantioselective Aryl C–H Addition to Nitroalkenes

Spiro cyclopentadienyl rhodium (SCpRh) complexes are powerful catalysts for promoting asymmetric C–H functionalization reactions. However, the application of chiral SCp ligands is limited due to tedious synthetic procedures and expensive starting materials. Herein, we have developed a series of chiral spiro ligands (BCSCp) with 6–7 steps from commercially available and cheap Bisphenol C. Their corresponding rhodium complexes have been prepared and successfully applied in enantioselective aryl C–H addition to nitroalkenes, affording a series of C–H adducts in up to 88% yield with up to 98% ee.