A helically twisted imine macrocycle that allows for determining the absolute configuration of α-amino carboxylates

Abstract

Binding of α-amino carboxylates to a helically twisted imine macrocycle based on the indolocarbazole scaffold gives rise to characteristic circular dichroism spectra, and the patterns of the Cotton effects are consistent with the absolute configuration of α-amino carboxylates.

An indolocarbazole dimer as a new stereodynamic probe for chiral 1,2-diamines

“…8,10 A simple mixing of 1 and 1,2-diamines 2c-2h afforded the corresponding cyclic diimines 3c-3h at room temperature ( Fig. 3 and ESI Fig.…”

“…2). 8 In order to demonstrate the scope and generality of this finding, we herein describe the CD spectral behaviours of other cyclic diimines 3c-3h derived from commercially available diamines 2c-2h. The patterns of the CD spectra strictly depend on the absolute configurations of chiral 1,2-diamines and therefore 1 can also serve as a stereodynamic probe for chiral 1,2-diamines.…”

“…8 Upon coupling with ethane-1,2-diamine (2a) in the presence of a carboxylate, 1 with two aldehyde groups at the ends was converted to the corresponding cyclic diimine 3a that adopted a helical conformation 9 (Scheme 1).…”

Ion and Molecular Recognition Using Aryl–Ethynyl Scaffolding

“…[90, 91] Bis(ethynyl- indolocarbazole)s with appended aryl-aldehydes such as 38 form chiral helices in the presence of N -Boc protected amino acids; these helices can subsequently be locked in place by imine formation with ethylene-1,2-diamine. The resulting chiral macrocycles produce a large CD response, and calibration with mixtures of isomers permits rapid determination of ee for a given sample.…”

Chirality Sensing With Stereodynamic Biphenolate Zinc Complexes

“…The chiral amplification process and sensing response can then be exploited for qualitative and quantitative stereochemical analysis of the bound substrate. [16][17][18][19][20] Seminal progress with the development of a variety of chiroptical chemosensors and powerful chirality sensing assays that can be used for the determination of the absolute configuration and enantiomeric excess (ee) of many compounds has been made by Berova and Nakanishi, [21][22][23][24] Anslyn, [25][26][27][28][29] Canary, 30, 31 Joyce, 32 and Borhan. The covalent attachment of a chiral amino acid, carboxylic acid, amine, or alcohol was found to effectively disturb the racemic equilibrium of the biphenyl conformations in the probe, thus inducing spontaneous chirality amplification.…”