Diastereoselective synthesis of enantiopure C-2-symmetric dihaloferrocenes

1,1'-bis[(S)-4-isopropyloxazolin-2-yl]ferrocene was dilithiated with sec-Bu Li/TMEDA in Et2O to give a (R-p :R-p) : (R-p :S-p) selectivity of 10:1. Fol lowing addition of C2Cl6 or C2Br2Cl4 the resulting dichloro and dibromo der ivatives were subjected to oxazoline ring opening and further manipulation to provide enantiopure (S-p,S-p)-1,1'-dicarbomethoxy-2,2'-dihaloferrocenes, (S-p,S-p)-1,1'-di(hydroxymethyl)-2,2'-dihaloferrocenes and (S-p,S-p)-1,1'-d icarbaldehyde-2,2'-dihaloferrocenes.