Solution and Solid Phase Synthesis of Unusual a-Amino Acids From

clotting cascade proteins" and as a constituent of the peptide antibiotic lysobactin.'' L-
erythro-p-Hydroxyaspartic acid has been used in the synthesis of p-lactam antibioti~s.'~
&Amino aspartic acid 5.6 is less cornmon and has been isolated from
Streptomyces rirnosus cultures. It has been used to construct the core constituent of
lactarn 5.7 of the streptothricin class of antibioticsm and stmctudly similar bioth2' nie
well-known metalcomplexing propertiesa of diaminoacids have resulted in the
investigation of various diamino derivatives in the anti-tumor drug cis-platin?
Although not naturally occurring, 5-fluoroaspartic acid has been used as an
intermediate in the synthesis of 5-fiuoro~racil.~
Scheme 5.1
Unlike glutamate (Chapter 4), aspartate has no direct role in humans other than a
constituent of factor X in h~rnans."~ However, derivatized aspartic acids have been used
as probes inio the mechanistic action of various enzymes and cofactoa. The
stereochemistry of coenzyme BI2 isomerization has been investigated in the conversion