Z/E Isomerism in N伪-N伪-Disubstituted Hydrazides and the Amidoxy Bond: Application to the Conformational Analysis of Pseudopeptides Built of Hydrazinoacids and 伪-Ami
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- 作者：Philippe Le Grel ; Arnaud Sala眉n ; Cl茅mence Mocquet ; Barbara Le Grel ; Thierry Roisnel ; Michel Potel
- 刊名：Journal of Organic Chemistry
- 出版年：2011
- 出版时间：November 4, 2011
- 年：2011
- 卷：76
- 期：21
- 页码：8756-8767
- 全文大小：1103K
- 年卷期：v.76,no.21(November 4, 2011)
- ISSN：1520-6904
文摘
We have investigated the Z/E isomerism of the hydrazide link (CO-NH-N) and amidoxy link (CO-NH-O). The study was first focused on small molecular models using NMR and X-ray diffraction. It allowed determination of simple NMR criterions to differentiate easily the Z and E forms, which were then applied to investigate the behavior of these links inside the corresponding oligomers. Our results concerning the hydrazide link corroborate pioneering work that had been done in the 1970s except in the case were it is located inside aza-尾3-cyclopeptides, where the old empirical rules failed to predict the right geometry of the link. The geometrical preference of the amidoxy bond is also unambiguously established and differs clearly from recent theoretical calculations. Our findings help rationalize the close self-organization ability of aza-尾3-peptides and 伪-aminoxypeptides, two recently described foldamers.