Diastereoselective lithiation of (eta6-arene)dicarbonyltriphenylphosphane chromium(0) oxazoline complexes--direct preparation of enantiopure complexes having planar chiral fragments of either configuration.

Abstract

Incorporation of a triphenylphosphane ligand is the key to the direct lithiation of (η6-2-phenyloxazoline)chromium(0) complexes. As diastereoselection can be modulated by the presence or absence of N,N,N′,N′-tetramethylethylenediamine (TMEDA), both diastereomers of 1,2-disubstituted η6-arene chromium(0) oxazoline complexes, which possess planar chiral moieties of opposite absolute configuration, can be prepared in useful chemical yields and high diastereoselectivities (10–50:1).