115. M.P. Doyle, W.R. Winchester, M.N. Protopopova, P. Müller, G. Bernardinelli, D. Ene, S. Motallebi,
     “Tetrakis[(4S)-4-phenyloxazolidin-2-one]dirhodium(II) and Its Catalytic Applications for Metal Carbene Transformations”
     Helv. Chim. Acta 1993, 76, 2227-2235.

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 thecis-cyclopropane.

DOI : 10.1002/hlca.19930760606 

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