ISSN:
0570-0833
Keywords:
3-Amino-2H-azirines
;
Azirines
;
Amino acids
;
Peptides
;
Heterocycles
;
Synthetic methods
;
2-Aminoisobutyric acid
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The recent upswing in peptide chemistry has been accompanied by an increasing interest in nonproteinogenic amino acids. These include the α,α-disubstituted glycines, the best known of which is Aib (2-aminoisobutyric acid, 2-methylalanine). These α-amino acids occur in natural oligopeptides such as the peptaibols, a class of membrane-active ionophores that has been isolated from fungal cultures. The twofold substitution at the α-C atom of the amino acids severely restricts the conformational freedom of the peptides and causes particular secondary structures to be favored; thus, α, α-disubstituted α-amino acids induce the formation of β turns or helices. 3-Amino-2H-azirines are ideal synthons for the construction of oligopeptides, cyclic peptides and depsipeptides (peptolides) containing such α,α-disubstituted α-amino acids. The presence of the ring strain in these molecules means that they can be used in peptide coupling without the need for additional activating reagents. Using 3-amino-2H-azirines a large array of heterocycles containing α, α-disubstituted α-amino acids as structural elements within their skeleton can be synthesized. The driving force in these reactions is the release of the strain on the three-membered ring, which usually takes place in a ring-expansion reaction. The mechanistic elucidation of these reactions, which can be quite complex, contains some surprises.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/anie.199102381
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