Catalytic Enantioselective Tandem Carbonyl Ylide Formation/1,3-Dipolar Cycloaddition Reactions of α-Diazo Ketones with Aromatic Aldehydes using Dirhodium(II) Tetrakis[N-benzene-fused-phthaloyl-(S)-valinate]

The first successful example of the enantioselective intermolecular 1,3‐dipolar cycloaddition of a chiral dirhodium(II) catalyst‐associated carbonyl ylide with an aromatic aldehyde dipolarophile is described. The tandem carbonyl ylide formation/cycloaddition reactions of 1‐diazo‐5‐aryl‐2,5‐pentanediones with aromatic aldehydes using dirhodium(II) tetrakis[N‐benzene‐fused‐phthaloyl‐(S)‐valinate] as a catalyst provide exclusively exo cycloadducts in up to 92 % ee.