Highly Efficient and Enantioselective α-Arylation of Cycloalkanones by Scandium-Catalyzed Diazoalkane-Carbonyl Homologation

Functionalized alpha-tertiary and -quaternary 2-arylcycloalkanones are rapidly accessed by scandium(III) triflate-catalyzed diazoalkane-carbonyl homologations. Recent developments have allowed for carbon insertion reactions to be performed with catalyst loadings as low as 0.5 mol% on scales up to 5 mmol. Pairing readily available bis- and tris(oxazoline) based ligands with scandium triflate allows access to arylated medium ring carbocycles with enantioselectivities up to 98: 2 er and > 98% yield. The formal C-C insertion of aryldiazomethanes into unsubstituted cycloalkanones provides a single-step solution to the ongoing challenge of alpha-arylation.