Synthesis and Structure of Planar Chiral, Bifunctional Aminoboronic Acid Ferrocene Derivatives

N,N ‘-Diisopropylferrocenecarboxamide is utilized for an asymmetric, directed metalation approach to several planar chiral bifunctional ferrocene derivatives. Directed metalation using n -butyllithium-(−)-sparteine on N,N ‘-diisopropylferrocenecarboxamide can be achieved to give high yields of the corresponding boronic acid; however, it was found that a sequence involving asymmetric directed metalation−bromination, followed by lithium−halogen exchange, was more convenient to access the same derivatives since this allowed straightforward determination of the enantiomeric excess. (p R )-2-[( N,N -Diisopropylamino)methyl]ferrocenylboronic acid and derivatives thereof could be readily accessed with high enantiomeric excess, followed by amide reduction.