Hydrazinopeptide Motifs Synthesized via the Ugi Reaction: An Insight into the Secondary Structure
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A number of Na-alkyl,N߭acylhydrazines have been synthesized via the Ugi reaction of N-acylhydrazones with an isocyanide and trifluoroacetic acid. The trifluoroacetic acid acted as a 'silent partner' and becomes removed upon basic workup of the reaction. These compounds have been efficiently modified further via reductive alkylation to produce Na,Na-dialkyl,N߭acylhydrazines. The two groups of novel hydrazinopeptide motifs have been shown by simple 鈠NMR spectroscopic experiments to display two different secondary structure patterns. These observations were confirmed by X-ray crystallographic analysis. Combining the hydrazone and carboxylic acid moieties in one reaction precursor offers the opportunity for an 'intramolecular' hydrazino-Ugi reaction, which was also demonstrated.
Copyright 2010 Georg Thieme Verlag. This is the author-manuscript version of the paper. Reproduced in accordance with the copyright policy of the publisher. The definitive version is available at www.thieme-connect.com
Organic Chemical Synthesis