Diastereoselective Pd-Catalyzed C-H Arylation of Ferrocenylmethanamines with Arylboronic Acids or Pinacol Esters.

An efficient diastereoselective synthesis of planar chiral ferrocenes via Pd(II)-catalyzed direct C-H activation with arylboronic acids or pinacol esters is presented. The reaction was performed under mild conditions using commercially available achiral or chiral amino acids as ligands. The best results were obtained with ( R)-Boc-alanine, which yielded products in 27-83% yield with diastereoselectivities ranging from 5:1 to 20:1 (11 examples). Diastereoisomeric products can also be obtained using ( S)-Boc-alanine as a ligand. Stereoinduction of the reaction was explained by density functional theory calculations of possible transition states.