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. (pR)-2-[(N,N-Diisopropylamino)methyl]ferrocenylboronic acid and derivatives thereof could be readily accessed
with high enantiomeric excess, followed by amide reduction.