Tetrakis[(4S)‐4‐phenyloxazolidin‐2‐one]dirhodium(II) and Its Catalytic Applications for Metal Carbene Transformations

The synthesis and X‐ray structure of the binuclear complex tetrakis[(4S)‐4‐phenyloxazolidin‐2‐one]‐dirhodium(II) ([Rh2{(4S)‐phox}4]) are reported. Structure‐selectivity comparisons are made for typical metal carbene transformations, such as inter‐ and intramolecular cyclopropane formation, intermolecular cyclopropene formation and intramolecular C–H insertions of diazoacetates and diazoacetamides. The enantioselectivity achieved in the [Rh2{(4S)‐phox}4]‐catalyzed reactions is intermediate between that of [Rh2{(5S)‐mepy}4] and [Rh2{(4R)‐bnox}4], which were described previously (mepy = methyl 5‐oxopyrrolidine‐2‐carboxylate; bnox = 4‐benzyloxazolidin‐2‐one). In contrast to other catalyzed intermolecular cyclopropane formations, those using [Rh2{(4S)‐phox}4] result preferentially in formation of the cis‐cyclopropane.