Synthese eines isomerenfreien Tetravalin‐Derivates durch stereoselektive Vier‐Komponenten‐Kondensation und exponentielle Selektivitätsverstärkung

Abstract

Die Peptid‐Synthese durch Vier‐Komponenten‐Kondensation läßt sich jetzt so gestalten, daß praktisch isomerenfreie Produkte entstehen. Der Trick besteht in der Verwendung eines asymmetrisch induzierenden Reagens (das zurückgewonnen wird) und in einer exponentiellen Selektivitätsverstärkung durch selektive Acidolyse des zunächst gebildeten Diastereomerengemisches.magnified image

Asymmetric Multicomponent Reactions (AMCRs): The New Frontier

“…In this case, the reaction of the chiral ferrocenylimine derivative 88 with N-formylvaline and the isocyanide obtained by reaction of the formylation/dehydration of the divaline dipeptide gave the expected tetrapeptide in modest yield but with excellent diastereoselectivity. [154] …”

Chemistry and Biology Of Multicomponent Reactions

“…53 Also it is well known that dipeptide derived or longer isocyanides are configurationally stable. 54 Additionally, orthoesters have been recently introduced as new racemisation free protecting groups for α-amino acid derived isocyanides. These materials have the additional advantage of being solid and odour less.…”

Chapter 14. Biological chemistry. Part (i) Peptides and proteins

“…A new peptide structurally quite distinct from those hitherto found in amphibian frogs has been isolated from Xenopus Zaevis. This octapeptide (28), xenopsin, has hypotensive properties and contracts rat stomach Qu-Gl y-Lys-Arg-Pro-Trp-Ile-Leu-OH (28) strip in vitro. The des-Leu' analogue is inactive, but Arg-Pro-Trp-Ile-Leu is weakly active, which is consistent with the observation that tryptic digestion does not completely inactive x e n o p ~i n .…”