High enantiocontrol in the intramolecular cyclopropanation of diazo ketones catalyzed by dirhodium(II) complexes with ortho-metalated aryl phosphine ligands

[GRAPHICS] Chiral dirhodium(II) complexes, Rh-2(O2CCF3)(2)(PC)(2), [PCH = (p-CH3C6H4)(3)P, (m-CH3C6H4)(3)P], provide an excellent yield and a high enantiocontrol in the cyclopropanation of alpha -diazo ketones with gamma and delta double bonds. The ee values are significantly dependent on the solvent used the best results are obtained using pentane.