Synthesis and structure of novel chiral oxazolinylferrocenes and oxazolinylferrocenylphosphines, and their rhodium(I)-complexes

A variety of chiral oxazolinylferrocenes are prepared from either ferrocenecarboxylic acid or cyanoferrocene and chiral beta-amino alcohols. Highly diastereoselective ortho-lithiation (84 similar to 99% de) of the oxazolinylferrocenes is accomplished with sec-butyllithium and the treatment of the lithiated compounds with an electrophile such as MeI, Ph(2)PCl or (PhSe)(2) gives the corresponding ortho-substituted oxazoliny)ferrocenes. The molecular structure of (S,S)-[2-(4'-isopropyloxazolin-2'-yl)fer (10), (S,S)-2-phenylseleno-1-(4'-isopropyloxazolinyl)ferrocene]diphenylphosphine (17), (S, R)-3-methyl-1-diphenylphosphino-2-(4'-isopropyloxazol)ferrocene (18), and (S,S,S)-[2-(4',5'-diphenyloxazolin-2'-yl)ferrocenylphosphines ((S,S,S)-DIPOF; 21) has been fully characterized by X-ray crystallography. In connection with their usefulness as chiral ligands for Rh(I)-catalyzed asymmetric hydrosilylation of ketones, the square planar transition metal complexes having oxazolinylferrocenylphosphines, such as [Rh(COD)(P-N)]BF, and Rh(CO)(P-N)Cl (P-N = 10 or 21), are prepared by treatment of [Rh(COD)(2)]BF(4) and [Rh(CO)(2)Cl](2) with 10 and 21, respectively, and all structures have been characterized spectroscopically and further confirmed by X-ray crystallography. (C) 1997 Elsevier Science S.A.