Stereoselective synthesis of planar chiral 2,2′-diarylsubstituted ferrocene derivatives as precursors for new 2-phospha[3]ferrocenophanes

Starting from a 1,1′-bis-(SC)-(methoxymethyl)pyrrolidine functionalized ferrocene, an ortholithiation/iodination/chiral auxiliary removal/Suzuki coupling sequence has been achieved. It affords a convenient, stereoselective access to chiral, C2-symmetric, tetrasubstituted ferrocene derivatives of (Spl,Spl)-configuration, bearing various aryl substituents and acetoxymethyl functions. These α-acetoxy-functionalized ferrocenes may be useful synthetic intermediates. In this work they were used as precursors for two new enantiomerically pure (Spl,Spl)-2-phospha[3]ferrocenophanes for organocatalytic purposes.

C2- symmetric, tetrasubstituted ferrocenes of (S)-planar configuration, bearing various aryl substituents and acetoxymethyl functions, have been prepared by a diastereoselective approach including ortho-lithiations and Suzuki couplings. These practical synthetic intermediates have been used as precursors for two new enantiomerically pure (Spl, Spl)-2-phospha[3]ferrocenophanes.Figure optionsDownload as PowerPoint slideHighlights
► Highly diastereoselective ortholithiations lead to planar chiral ferrocenes.
► Double Suzuki couplings are applied to the synthesis of tetrasubstituted ferrocenes.
► New chiral 2-phospha[3]ferrocenophanes have been prepared.