Publication

Stereocontrol during the formation of 2-C mono-arylated pseudo-prolines by aromatic stacking interaction

1999
Journal Articles

Abstract

When treated with anisaldehyde dimethylacetal the O-benzyl ester protected dipeptide Fmoc-NMeIle-Thr-OBzl (2, cf. Scheme 3), cyclizes to the 2-C(S) epimer 3b assigned by NMR spectroscopy to chirality (R) at the 2-C position of the resulting substituted 1,3-oxazolidine (Psi Pro) unit, while in the acetalization of the corresponding O-methylester Fmoc-NMeIle-Thr-OMe (6),the 2-C(S) epimer 7a is predominantly formed stereoselectively and in quantitative yield. The course of the reaction can be rationalized by aromatic stacking interactions involving the benzyl ester and aryl ether groups in a transition state close to a product structure of(R) chirality, whereas the lack of such interactions in the case of the methyl ester can be used to direct the acetalization towards the 2-C(S) epimer. (C) 1998 Elsevier Science Ltd. All rights reserved.

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https://infoscience.epfl.ch/entities/publication/9df11c0b-1f9b-4533-8c25-687789603724

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1999
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/9df11c0b-1f9b-4533-8c25-687789603724

About this result

Related concepts (17)

Cation–π interaction

Cation–π interaction is a noncovalent molecular interaction between the face of an electron-rich π system (e.g. benzene, ethylene, acetylene) and an adjacent cation (e.g. Li+, Na+). This interaction is an example of noncovalent bonding between a monopole (cation) and a quadrupole (π system). Bonding energies are significant, with solution-phase values falling within the same order of magnitude as hydrogen bonds and salt bridges.

Pi-interaction

In chemistry, π-effects or π-interactions are a type of non-covalent interaction that involves π systems. Just like in an electrostatic interaction where a region of negative charge interacts with a positive charge, the electron-rich π system can interact with a metal (cationic or neutral), an anion, another molecule and even another π system. Non-covalent interactions involving π systems are pivotal to biological events such as protein-ligand recognition.

Non-covalent interaction

In chemistry, a non-covalent interaction differs from a covalent bond in that it does not involve the sharing of electrons, but rather involves more dispersed variations of electromagnetic interactions between molecules or within a molecule. The chemical energy released in the formation of non-covalent interactions is typically on the order of 1–5 kcal/mol (1000–5000 calories per 6.02 molecules). Non-covalent interactions can be classified into different categories, such as electrostatic, π-effects, van der Waals forces, and hydrophobic effects.

Related publications (1)

Stereocontrol during the formation of 2-C mono-arylated pseudo-prolines by aromatic stacking interaction

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