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products was evaluated by HPLC using a chiral station-
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alanine (3a, 4a and 5a) and D-alanine (3d, 4d and 5d),
respectively. In cases where the retention time was deter-
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was estimated by assuming a similar separation factor
and detection limit as in the chromatograms of the
above mentioned compounds.
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The 12 new compounds synthesized (Table 1) represent
a set of potentially useful peptidomimetic building
blocks. The methylene groups separating the heterocycle
and the carboxyl functionality are employed as a spacer
to allow for increased conformational flexibility and also
to render the compounds more stable. The amidoxime
precursors are derived from a-amino acids, using a sim-
ple synthetic route affording the products in good yields.
In addition, the chirality of the starting amino acids is
retained during the whole process due to the mild reac-
tion conditions.
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Acknowledgements
This work was supported financially by the Ministry of
Higher Education, Science and Technology of the
Republic of Slovenia. The authors thank Professor Dr.
Roger Pain for a critical reading of the manuscript.
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