Asymmetric synthesis of rigid C-2-symmetric bis(ferrocenyl) diol and diamine ligands

We report herein the asymmetric synthesis of C-2-symmetric fused diferrocen yl diamine and diol ligands. The synthesis begins with the Cu(II)-mediated coupling of the diastereomerically and enantiomerically pure lithiated deri vative of Kagan's ferrocenyl acetal to yield, after deprotection, the C-2-s ymmetric biferrocenyl dialdehyde 4. Conversion of dial 4 to a bis(methylimi ne) followed by a SmI2 mediated aza-pinacol coupling, yielded the enantio- and diastereomerically pure C-2-symmetric trans-diamine 1. The direct pinac ol coupling of dialdehyde 4 by SmI2 yields the enantio- and diastereomerica lly pure C-2-symmetric trans-diol 2. The former diamine was coordinated to the Lewis acid (ArO)(2)TiCl2 (Ar = 4-vinyl-2,6-dimethylphenyl) and characte rized by solution and X-ray methods. The diol ligand was reacted with (dppe )Pt(CO3) to form a (dppe)Pt-II diolate, which was also characterized by sol ution and solid-state means.