A novel approach to ferrocenes with planar chirality

The 2-metalation of enantiomerically pure (S)-(2-methoxy-methylpyrrolidin-1-yl)ferrocene FcSMP (1) with BuLi proceeds with high diastereoselectivity (up to 98% de) to yield the Ph(2)P-substituted ferrocene (S,S-p)-2a after quenching with Ph(2)PCl. The SMP moiety was removed by heating of 2a at reflux in acetic anhydride to give planar chiral (S-p)-2-diphenylphosphanylferrocenylmethyl acetate (5). The diastereoisomer (S,R(p))-2b was synthesized from 1 by intermediately blocking the primary metalation site with a Me(3)Si group which can be removed afterwards by treatment with KOtBu in DMSO. Compound 2a was treated with [(C3H5)PdCl](2) to give the complex [(C3H5)Pd . 2a]PF6 (7 . PF6). The structure of 7 . PF6 was determined by a single-crystal X-ray diffraction study and showed 2a to act as a bidentate P,N-chelate ligand.