Resolution of Planar Chiral Cationic (η~6-Arene)tricarbonylmanganese Complexes

摘要

Planar chiral transition-metal π complexes of ortho- and meta-disubstituted arenes, such as (η~6-arene)tricarbonylchromium complexes, have been widely applied as stoichiometric auxiliaries and suitable starting materials for asymmetric preparation of biologically active substances as well as ligands for asymmetric catalysis. In contrast, very little is known about the planar chirality of the isoelectronic cationic (η~6-arene)tricarbonylmanganese complexes, in spite of their potential usefulness. Indeed, there have been no reports of their resolution, and to date the synthesis of only two nonracemic planar chiral cationic η~6-arene-Mn complexes starting from (p-cresol)Mn(CO)_3~+ has been described. In this context, the discovery of a general methodology for preparing enantiomerically pure planar chiral cationic η~6-arene-Mn complexes may be deemed as an exciting challenge.