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.