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.