Asymmetric Rh(II)/Pd(0) Relay Catalysis: Synthesis of α-Quaternary Chiral β-Lactams through Enantioselective C-H Insertion/Diastereoselective Allylation of Diazoamides

A straightforward route toward construction of α-quaternary chiral β-lactam moiety via Rh(II)/Pd(0)-catalyzed stereoselective relay catalytic reaction is reported. This asymmetric dual relay catalysis involves Rh(II)-catalyzed enantioselective intramoluecular C-H insertions of α-diazoamides, and sequential Pd(0)-catalyzed diastereoselective intermolecular allylic alkylation. Under mild reaction conditions, a broad range of α-quaternary allylated chiral β-lactams have been synthesized in high yields (up to 99%) with excellent stereoselectivities [up to diastereomeric ratio (dr) >99:1, up to 98% enantiomeric excess (ee)].