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.