Highly Regio- and Enantioselective Synthesis of 4-Substituted Dihydroisoquinolones Catalyzed by a Planar-Chiral Rhodium(III) Catalyst Bearing a Penta-Substituted Prochiral Cyclopentadienyl Ligand

-butyl and 4-benzyl tetrahydroisoquinolines. Mechanistic studies have been conducted, including H/D exchange, kinetic isotope effect (KIE), and capture of the metallacyclic intermediate. The 1,3,4-triaryl-2,5-dialkyl cyclopentadienyl moiety proves to be the key structural feature for achieving high regioselectivity. The cyclopentadienyl ligand adopts a well-defined conformation in the metallacycle intermediate formed during C-H activation. Density functional theory (DFT) calculations revealed that the migratory insertion of olefin was irreversible, constituting the stereo- and regioselectivity-determining event.