AbstractThe synthesis, spectral characteristics, and X‐ray structures for dirhodium(II) tetrakis[methyl 2‐oxooxazolidin‐4(S)‐carboxylate], Rh2(4S‐MEOX)4, and the related dirhodium(II) tetrakis[methyl 5(R)‐methyl‐2‐oxooxazolidin‐4(S)‐carboxylate], Rh2(4S‐THREOX)4, are reported. Comparison is made between these 2‐oxooxazolidin‐ligated dirhodium(II) catalysts for metal carbene transformations and those with comparable 2‐oxopyrrolidine ligands, especially dirhodium(II) tetrakis[methyl 2‐oxopyrrolidine‐5(S)‐carboxylate], Rh2(5S‐MEPY)4. Structure‐selectivity comparisons reveal that Rh2(4S‐MEOX)4provides higher enantiocontrol and, in some cases, higher diastereocontrol than Rh2(5S‐MEPY)4in intramolecular carbon‐hydrogen insertion reactions of sterically demanding diazoacetates and diazoacetamides and is the catalyst of choice for highly enantioselective diazodecomposition of adamantyl diazoacetates andN‐(tert)butyldiazoacetamides. The structurally analogous Rh2(4S‐THREOX)4is nearly identical with Rh2(4S‐ MEOX)4in its overall effect on selectivity. The net advantage of Rh2(4S‐MEOX)4lies in i