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Updated: Dec 30, 2025

Preparation of Enantiopure Non-Activated Aziridines and Synthesis of Biemamide B, D, and epiallo-Isomuscarine
Published on: June 13, 2022
Size-Induced Chiral Discrimination Switching by (S)-(-)-2(α-Hydroxyethyl)Benzimidazole-Derived Azacrowns
Anita D Pandey1, Hasan Mohammed1, Raghuvir R S Pissurlenkar2
1Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India).
Abstract:
(S)-(-)-2-(α-Hydroxyethyl)benzimidazole (1)-derived diastereomeric monoaza-[18]crown-6 compounds 5 and 6 were synthesised with an additional chiral centre bearing a phenyl ring. The aim was to achieve enhanced enantioselective discrimination, compared with monoaza-[15]crown-5 (7). Surprisingly, reversal of enantioselective binding for chiral guest enantiomers between the two differently sized [15]crown-5 and [18]crown-6 azacrowns were discovered; all three were prepared from the same parent compound, 1. To complete the observations, another [18]crown-6-sized azacrown (10) without an additional chiral centre was synthesised from 1 and screened for its enantioselective binding abilities towards the chiral guest enantiomers investigated; these results corroborated the observations. Single-crystal XRD analysis and molecular docking studies revealed that changes to the conformational aspects of [18]crown-6 and [15]crown-5 azacrowns were the major contributing factors to this peculiar behaviour.
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