The Same and Not the Same: Chirality, Topicity, and Memory of Chirality

Krämer, Wolfgang; Griesbeck, Axel G.

doi:10.1021/ed085p701

Cited by 11 publications

(8 citation statements)

References 14 publications

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“…A second stereochemical peculiarity was the fact that these methoxy groups of 12 and 13 , although appearing so similar, were not homo- or enantiotopic, but diastereotopically related . For this reason, they should, in principle, give two NMR signals, but even at 600 MHz, these two signals were overlapped and just gave one six-proton singlet resonating at δ H 3.62, as monitored for 12 , and at δ H 3.61 as for 13 (see Table ).…”

Section: Resultsmentioning

confidence: 99%

Ancistrosecolines A–F, Unprecedented seco-Naphthylisoquinoline Alkaloids from the Roots of Ancistrocladus abbreviatus, with Apoptosis-Inducing Potential against HeLa Cancer Cells

et al. 2020

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Ancistrosecolines A–F (8–13) are the first seco-type naphthylisoquinoline alkaloids discovered in Nature. In all these novel compounds, the tetrahydroisoquinoline ring is cleaved, with loss of C-1. They were isolated from the root bark of Ancistrocladus abbreviatus (Ancistrocladaceae), along with 1-nor-8-O-demethylancistrobrevine H (14), which is the first naturally occurring naphthylisoquinoline lacking the otherwise generally present methyl group at C-1. The stereostructures of the new alkaloids were established by HRESIMS, 1D and 2D NMR, oxidative degradation, and experimental and quantum-chemical ECD investigations. Ancistrosecolines A–F (8–13) and 1-nor-8-O-demethylancistrobrevine H (14) are typical Ancistrocladaceae-type metabolites, i.e., oxygenated at C-6 and S-configured at C-3, belonging to the subclasses of 7,1′- and 7,8′-coupled alkaloids. The biaryl linkages of 8–14 are rotationally hindered due to bulky ortho-substituents next to the axes. Owing to the constitutionally unsymmetric substitution patterns on each side of the axis, this C–C single bond represents an element of chirality in 1-nor-8-O-demethylancistrobrevine H (14) and in ancistrosecolines A–D (8–11). In ancistrosecolines E (12) and F (13), however, the likewise rotationally hindered biaryl axes do not constitute chiral elements, due to a symmetric substitution pattern, with its identical two methoxy functions at C-6 and C-8 in the phenyl subunit. And these two methoxy groups are, for the first time, not constitutionally heterotopic, but diastereotopic to each other. Ancistrosecoline D (11) exhibits strong cytotoxicity against HeLa cervical cancer cells. As visualized by Hoechst nuclei staining and by real-time imaging experiments, 11 induced massive nuclei fragmentation in HeLa cells, leading to apoptotic cell death.

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Section: Resultsmentioning

confidence: 99%

Ancistrosecolines A–F, Unprecedented seco-Naphthylisoquinoline Alkaloids from the Roots of Ancistrocladus abbreviatus, with Apoptosis-Inducing Potential against HeLa Cancer Cells

et al. 2020

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“…High enantioconservation is thus typically observed with singlet photochemistry. [80][81][82] This is also possible with triplet biradical intermediates which only slowly interconvert. 83,84 The benefit of TADF compounds is that they have the potential to access both FRET and DET pathways.…”

Section: Pent Photocatalysismentioning

confidence: 99%

Organic thermally activated delayed fluorescence (TADF) compounds used in photocatalysis

2021

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“…The chiral information is then conserved in more or less stable conformers or non-covalent interactions and the reactions remain stereoselective. This phenomenon is called "memory of chirality" [153][154][155][156].…”

Section: Memory Of Chiralitymentioning

confidence: 99%

“…Among numerous conformations in such a structure that one of a minimum of steric hindrance is privileged which has a significant impact on the stereoselectivity of these reactions [161,162]. It was shown for a similar electrochemical reaction that compound 87 was transformed into compound 88 with almost the same enantioselectivity but with retention of configuration [156,163,164]. This result was explained by the fact that the reaction step in which the center of chirality is created (89) takes place exclusively at the singlet state.…”

Section: Memory Of Chiralitymentioning

confidence: 99%

Enantioselective synthesis of heterocyclic compounds using photochemical reactions

Hoffmann

2021

Photochem Photobiol Sci

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Different methods for the direct enantioselective photochemical synthesis of heterocycles are presented. Currently, asymmetric catalysis with templates involving hydrogen bonds or metal complexes is intensively investigated. Enzyme catalysis can be simplified under photochemical conditions. For example, in multi enzyme systems, one or more enzyme catalytic steps can be replaced by simple photochemical reactions. Chiral induction in photochemical reactions performed with homochiral crystals is highly efficient. Such reactions can also be carried out with crystalline inclusion complexes. Inclusion of a photochemical substrate and an enantiopure compound in zeolites also leads to enantioselective compounds. In all these methods, the conformational mobility of the photochemical substrates is reduced or controlled. Memory of chirality is a particular case in which a chiral information is temporally lost but the rigid conformations stabilize the molecular structure which leads to the formation of enantiopure compounds. Such studies allows a profound understanding on how particular conformations determine the configuration of the final products.

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The Same and Not the Same: Chirality, Topicity, and Memory of Chirality

Abstract: Figure 1. Perspective drawing in chemistry.

Cited by 11 publications

References 14 publications

Ancistrosecolines A–F, Unprecedented seco-Naphthylisoquinoline Alkaloids from the Roots of Ancistrocladus abbreviatus, with Apoptosis-Inducing Potential against HeLa Cancer Cells

Ancistrosecolines A–F, Unprecedented seco-Naphthylisoquinoline Alkaloids from the Roots of Ancistrocladus abbreviatus, with Apoptosis-Inducing Potential against HeLa Cancer Cells

Organic thermally activated delayed fluorescence (TADF) compounds used in photocatalysis

Enantioselective synthesis of heterocyclic compounds using photochemical reactions

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