Aza-β3-cyclopeptides: A New Way of Controlling Nitrogen Chirality

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• 作者：Clmence Mocquet ; Arnaud Salan ; Paul Claudon ; Barbara Le Grel ; Michel Potel ; Gilles Guichard ; Brigitte Jamart-Grgoire ; Philippe Le Grel
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：October 14, 2009
• 年：2009
• 卷：131
• 期：40
• 页码：14521-14525
• 全文大小：261K
• 年卷期：v.131,no.40(October 14, 2009)
• ISSN：1520-5126

文摘

Sixteen and 24 membered aza-β³-peptidic macrocycles containing a α-hydrazinoacid or a β³-aminoacid were synthesized. The conformation of these pseudopeptides was determined by using NH chemical shift analysis, NH extinction, VT-NMR experiments, and X-ray diffraction. The study shows that a stable conformation is retained between 223 and 413 K. The latter is characterized by an uninterrupted internal H-bond network and a syndiotactic arrangement of the asymmetric centers. It means that the presence of the optically pure residue acts as a conformational lock to select a single enantiomer through the cyclization by controlling the absolute configuration of all the nitrogen atoms. To our knowledge, this represents the first example of a dynamic enantioselection process involving several centers prone to pyramidal inversion. These results give a new impulsion to the control of nitrogen chirality, which remained limited to small cycles for 60 years.