Diaminodicarboxylic acid

Scheme 12 a,a -Diaminodicarboxylic Acids as Dicarba-analogues of Cystine... 

A more strongly acidic solution is needed to repress this ionization. Aspartic acid s isoelectric point is strongly acidic (pH = 2.7). (d) Cystine is a diaminodicarboxylic acid and behaves like a monoaminomonocarboxylic acid. The isoelectric point is slightly acid (pH = 4.6). (e) Tyrosine is a monoaminomonocarboxylic acid containing a phenolic OH, which however is too weakly acidic to ionize to any significant extent. The isoelectric point is slightly acidic (pH = S.6). 

Reductive N-N cleavage of derivatives 28a and 28b gave the open-chain bis-carbamates 29a and 29b (Scheme 6) <1998AGE2242>. Another example of N-N reductive cleavage is observed in diazocines 30 (R = H, Me), which were converted into the z M-diaminodicarboxylic acid 31 (R = H) or ester (R = Me) by hydrogenolysis with Pt02 in 2N HC1 (Scheme 6) <1998CPB674>. 

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... 

Gosselin, E, and Lubell, W.D., Rigid dipeptide suirogates. Syntheses of enantiopure quinolizidinone and pyrroloazepinone amino acids from a coimnon diaminodicarboxylate precursor, 7. Org. Chem.. 65, 2163. 2000. 

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