Work

Stepwise Orthogonal Protection of Calix[4]arene Triamine: A Facile Route to Asymmetric Structures

Year: 2025

Type: article

Abstract: A cone calix[4]arene having one tert-butyl group and three amino groups at the wide rim was bis-N-protected stepwise using sulfonylation with 4-nitrobenzylsulfonyl chloride, followed by acylation with di-tert-butyl dicarbonate. The selective sulfonylation was shown to prefer the amino group located in the proximal calixarene aromatic unit relative to the tert-butylated moiety, resulting in the formation of an inherently chiral calix[4]arene with a wide-rim substitution pattern of AABC type. Further acylation of one of the two remaining amino groups also proceeded selectively. It involved the calixarene aromatic unit adjacent to the sulfonylated moiety, as clearly demonstrated by 2D NMR data for the ABCD-substituted reaction product, which was obtained as a mixture of enantiomers. The mixture was acylated with (R)-mandelic acid succinimide ester, and the resulting diastereomers were separated by conventional column chromatography, thus demonstrating the applicability of the stepwise protection strategy for the further preparation of enantiopure calix[4]arene cores possessing inherent chirality due to four different substituents at their wide rims.

Source: Molbank

DOI: 10.3390/m2115

Authors: Ivan Alekseev, Dmitry Cheshkov, Alexander Gorbunov, Vladimir Kovalev, Ivan Vatsouro

Institutions: Lomonosov Moscow State University, State Research Institute for Chemistry and Technology of Organoelement Compounds

Language: English

Topic: Supramolecular Chemistry and Complexes

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $603

Funder: Russian Science Foundation