Synthesis of Diaminodicarboxylic Acids

The chemistry of diaminodicarboxylic acids has gained great interest since these are important biological agents (Fig. 10.4). These compounds have inspired diverse syntheses of a number of structurally related unnatural diaminodicarboxylic acids intended to enhance the bioactivity and/or control the peptide secondary structure [45]. 

More recently, other authors have also applied the Bucherer-Bergs methodology for the synthesis of confor-mationally constrained diaminodicarboxylic acid derivatives (Fig. 10.5). 

In fact, Iverson and coworkers used the diaminodicarboxylic acid 52 for the synthesis of two novel, rigid, cis-55 and 

SCHEME 10.12 First-generation synthesis of LY2140023 46 through Bucherer-Bergs hydantoin. 

For the preparation of the dy-linker 55, a slight variation in the synthesis was required since the di-oriented bis-hydantoins cannot be obtained via Bucherer-Bergs reaction for this structure. 

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