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Two different types of chiral stationary phases, based on Pirkle's design, were created by attaching chiral selectors to 3‐mercapto silica gel. To prepare the enantiomeric selectors, 3,5‐dinitrobenzoyl and naphthyl groups were sequentially added to a chiral 1,2‐diaminocyclohexane core. The chiral selectors demonstrated enantioselectivity towards ibuprofen enantiomers in solution, as confirmed by 1H NMR spectroscopy, and in initial HPLC testing, the enantiomeric selectors showed enantioselectivity for selected racemic solutes (viz., α = 1.27 for1,1′‐bi‐(2‐naphthol)). Molecular docking studies revealed that the chiral selectors had a bent structure and a cleft‐like cavity where the analyte could be held during complexation while establishing H‐bonding and π–π stacking interactions. [ABSTRACT FROM AUTHOR]

We present the inaugural synthesis of a chiral teropyrene achieved through a four‐fold alkyne benzannulation catalyzed by InCl3, resulting in good yields. The product underwent thorough characterization using FT‐Raman and FT‐IR spectroscopies, demonstrating a close agreement with calculated spectra. X‐ray crystallographic analysis unveiled a notable twist in the molecule's backbone, with an end‐to‐end twist angle of 51°, consistent with computational predictions. Experimentally determined enantiomeric inversion barriers revealed a significant energy barrier of 23 kcal/mol, facilitating the isolation of enantiomers for analysis by circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopies. These findings mark significant strides in the synthesis and characterization of chiral teropyrenes, offering insights into their structural and spectroscopic properties. [ABSTRACT FROM AUTHOR]

Phyllanthus is a large genus of the Euphorbiaceae family, which has been widely used in traditional medicine. The current study reports the isolation of an unusual C-glycosyl flavonoid, named tenelloside, from Phyllanthus tenellus Roxb., a non-endemic plant present in Canary Islands. The chemical structure of this secondary metabolite was established employing combined spectrometric and spectroscopic techniques, including 1D and 2D NMR experiments and mass spectrometry. The absolute stereochemical configuration was determined via the comparison of experimental and calculated electronic circular dichroism spectra. In our previous work, another C-glycosylated bioactive product was isolated from another Phyllanthus species, suggesting that this class of compounds can be produced in a genus-specific manner in different geographic regions. This work represents another important report for direct future studies on the biological and chemotaxonomic potential of C-glycosylated products of the Phyllanthus genus. [ABSTRACT FROM AUTHOR]

Herein, we report on the synthesis and high-performance liquid chromatography (HPLC) resolution of a new atropisomeric C2-symmetry chiral monomer based on the 3,3′-bithiophene core, which was developed to produce novel, inherently oligomeric chiral electroactive materials. The analytical enantioseparation was optimized using the cellulose-type Chiralpak IB-3 column and a mixture of n-hexane–methanol–dichloromethane 90:5:5 (v/v/v) as the mobile phase. During the scale-up of the enantioseparation analytical conditions to a semipreparative level, remarkable deformations in the HPLC profile, such as peak splitting and plateau zones between enantiomeric peaks, were observed. We demonstrate the effects of sample diluent as they relate to distorted peak profiles, as well as provide experimental solutions to prevent the disturbing phenomenon. The optimized chromatographic conditions were exploited to collect milligram amounts of the enantiopure sample, which was submitted to chiroptical and stereochemical characterization studies. [ABSTRACT FROM AUTHOR]

Helicenes combine two central themes in chemistry: extended π‐conjugation and chirality. Hetero‐atom doping preserves both characteristics and allows modulation of the electronic structure of a helicene. Herein, we report the (BO)2‐doped tetrathia[7]helicene 1, which was prepared from 2‐methoxy‐3,3′‐bithiophene in four steps. 1 is formally derived by substituting two (Mes)B−O moieties in place of (H)C=C(H) fragments in two benzene rings of the parent tetrathia[7]helicene. X‐ray crystallography revealed a dihedral angle of 50.26(9)° between the two terminal thiophene rings. The (P)‐/(M)‐1 enantiomers were separated by chiral HPLC and are configurationally stable at room temperature. The experimentally determined enantiomerization barrier of 27.4±0.1 kcal mol−1 is lower than that of tetrathia[7]helicene (39.4±0.1 kcal mol−1). The circular dichroism spectra of (P)‐ and (M)‐1 show a perfect mirror‐image relationship. 1 is a blue emitter (λem=411 nm) with a photoluminescence quantum efficiency of ΦPL=6 % (cf. tetrathia[7]helicene: λem≈405 nm, ΦPL=5 %). [ABSTRACT FROM AUTHOR]

The field of organocatalysis is expanding at a fast pace. Its growth is sustained by major stimuli, such as the effort toward an understanding of the mechanisms of reaction and catalytic processes in general, the elucidation of basic properties leading to stereocontrol and the search for broad applicability and scalability of the synthetic methodology. This paper reports a thorough study based on ESI‐MS spectrometry of amino‐organocatalyzed model reactions under different experimental conditions. Off‐line reaction monitoring of mixtures containing different catalytic systems, by ESI‐MSn showed the presence of several putative intermediate species, either in their protonated or sodiated forms. In addition, enantioselective chromatography of crude reactions provides the stereochemical outcome of asymmetric reactions. The bulk of the data collected offers a clue of the intricate pathways occurring in solution for the studied reactions. [ABSTRACT FROM AUTHOR]

Two chiral triptycene derivatives were analyzed on the Chiralpak IB‐U column packed with cellulose tris(3,5‐dimethylphenylcarbamate)‐based sub‐2‐μm diameter particles. Under normal‐phase conditions, sub‐minute baseline enantioseparations were obtained. Differences in structural elements and chromatographic behavior of the investigated compounds were evaluated to identify the interactions that drive the chiral discrimination process. From the evaluation of the experimental chromatographic data, it was found that hydrogen bond formation is essential for the separation of enantiomers. [ABSTRACT FROM AUTHOR]

Helicenes combine two central themes in chemistry: extended π-conjugation and chirality. Hetero-atom doping preserves both characteristics and allows modulation of the electronic structure of a helicene. Herein, we report the (BO) 2 -doped tetrathia[7]helicene 1, which was prepared from 2-methoxy-3,3'-bithiophene in four steps. 1 is formally derived by substituting two (Mes)B-O moieties in place of (H)C=C(H) fragments in two benzene rings of the parent tetrathia[7]helicene. X-ray crystallography revealed a dihedral angle of 50.26(9)° between the two terminal thiophene rings. The (P)-/(M)-1 enantiomers were separated by chiral HPLC and are configurationally stable at room temperature. The experimentally determined enantiomerization barrier of 27.4±0.1 kcal mol -1 is lower than that of tetrathia[7]helicene (39.4±0.1 kcal mol -1 ). The circular dichroism spectra of (P)- and (M)-1 show a perfect mirror-image relationship. 1 is a blue emitter (λ em =411 nm) with a photoluminescence quantum efficiency of Φ PL =6 % (cf. tetrathia[7]helicene: λ em ≈405 nm, Φ PL =5 %)., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)