Synthesis of 1,8-Diazaanthracenes as Building Blocks for Internally Functionalized Aromatic Oligoamide Foldamers

The
synthesis of a variety of 9-functionalized 1,8-diazaanthracene
diesters and amino acids is described. Derivatization at the 9-position
relies on facile reactions performed on the 9-chloro and 9-bromomethyl
precursors. This has allowed the incorporation of nucleophilic or
sensitive functional groups that otherwise cannot be incorporated
under standard methods for synthesizing these compounds. Additionally,
the synthesis of the protected amino acids via a high-yielding monosaponification
and subsequent Curtius rearrangement has been accomplished on a multigram
scale. These units, together with the functionalized derivatives,
should prove to be useful monomers in the synthesis of aromatic oligoamide
foldamers.