Enantioselective Synthesis of Dithia[5]helicenes and their Postsynthetic Functionalization to Access Dithia[9]helicenes

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 61(6)

Published: Dec. 7, 2021

A highly enantioselective synthesis of 5,13-disubstituted dibenzo[d,d']benzo[1,2-b:4,3-b']dithiophenes is reported. Key for the successful assembly these helical architectures last two successive Au-catalyzed intramolecular alkyne hydroarylation events. Specifically, second cyclization enantiodetermining step whole process and provides desired helicenes with excellent ee values when a TADDOL-derived 1,2,3-(triazolium)phosphonite moiety (TADDOL: α,α,α',α'-tetraaryl-1,3-dioxolane-4,5-dimethanol) employed as an ancillary ligand. The absolute stereochemistry newly prepared structures has been determined by X-ray crystallography to be P; optical properties heterohelicenes are also three-step procedure was subsequently developed that allows transformation initially obtained dithia[5]helicenes into dithia[9]helicenes without erosion enantiopurity.

Language: Английский

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Triple Oxa[7]helicene with Circularly Polarized Luminescence: Enhancing the Dissymmetry Factors via Helicene Subunit Multiplication

Organic Letters, Journal Year: 2021, Volume and Issue: 23(12), P. 4559 - 4563

Published: May 27, 2021

The development of multiple heterohelicenes with a high luminescence dissymmetry factor (glum) is an appealing yet challenging task. Herein, we disclose the synthesis structurally unusual furan-based triple oxa[7]helicene, which represents first reported hetero[7]helicene, via [2+2+2] cyclotrimerization/intramolecular dehydrogenative annulation. Compared to double oxa[7]helicene exhibits improved glum value 1.8 × 10–3, exemplifying potential helicene subunit multiplication approach enhance heterohelicenes.

Language: Английский

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Synthesis, Structures and Properties of Trioxa[9]circulene and Diepoxycyclononatrinaphthalene

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(23)

Published: April 2, 2024

This article presents trioxa[9]circulene (3) as a novel member of hetero[n]circulenes. Its synthesis began with the dimethoxydioxa[8]helicene (5) and used dimethoxydiepoxycyclononatrinaphthalene (4) key intermediate, despite condensation reaction predominantly yielding 1,4-addition byproduct. The structures properties 3-5 were extensively investigated using experimental computational methods. Analysis crystal reveal elongation internal C-C bonds in nine-membered ring 3 compared to 4 5. Computational studies demonstrate remarkable flexibility trioxa[9]circulene's saddle-shaped polycyclic framework, while other two compounds are rigid large racemization barriers. Optically pure forms 5 exhibit absorption luminescence dissymmetry factors on order 10

Language: Английский

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Hydroxylation-Depolymerization of Oxyphenylene-Based Super Engineering Plastics To Regenerate Arenols

JACS Au, Journal Year: 2023, Volume and Issue: 3(8), P. 2323 - 2332

Published: Aug. 17, 2023

Super engineering plastics, high-performance thermoplastic resins, show high thermal stability and mechanical strength as well chemical resistance. On the other hand, recycling for these plastics has not been developed due to their stability. This study describes depolymerization of oxyphenylene super via carbon–oxygen main chain cleaving hydroxylation reaction with an alkali hydroxide nucleophile. method is conducted cesium a hydroxy source calcium hydride dehydration agent in 1,3-dimethyl-2-imidazolidinone, which provides hydroxylated monomers effectively. In case polysulfone, both 4,4′-sulfonyldiphenol (bisphenol S) 4,4′-(propane-2,2-diyl)diphenol A) were obtained yields. Other such polyethersulfone, polyphenylsulfone, polyetheretherketone also applicable this depolymerization.

Language: Английский

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Enantioselective Au‐Catalyzed Synthesis of Thia[5]‐ and Thia[6]helicenes and Their Transformation into Bowl‐shaped Pleiadenes

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(17)

Published: Feb. 7, 2023

A series of helically shaped benzo[b]chryseno[4,3-d]thiophenes, naphtho[1,2-b]phenanthro[4,3-d]thiophenes, and chryseno[3,4-b]naphtho[1,2-d]thiophenes is synthesized via a highly enantioselective Au-catalyzed intramolecular alkyne hydroarylation reaction. The inversion barriers the structures obtained are determined both theoretically experimentally, their chiroptical properties reported. Preliminary studies on post-synthetic functionalization these thiahelicenes transformation into azahelicenes also presented. In addition, straightforward one-step protocol developed, which wraps initially bowl-shaped pleiadene derivatives without erosion enantiopurity. number structurally related products that with high enantioselectivity enables establishment comprehensive correlations between structure conformational stability or (chir)optical properties.

Language: Английский

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Recent development of azahelicenes showing circularly polarized luminescence

Chemical Communications, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

This feature article summarizes the recent developments of azahelicenes showing circularly polarized luminescence.

Language: Английский

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Aromatic Metamorphosis: Skeletal Editing of Aromatic Rings

Accounts of Chemical Research, Journal Year: 2025, Volume and Issue: unknown

Published: April 2, 2025

ConspectusAromatic rings are fundamental structural motifs found in natural products, synthetic intermediates, pharmaceuticals, agrochemicals, and functional materials. While transformations at the periphery of these well-established, modifying their core frameworks has remained an underexplored frontier. Our group pioneered concept, termed "aromatic metamorphosis", enabling skeletal aromatic by replacing endocyclic atom with a different or inserting into rings, which leads to novel strategies diverse molecular architectures.The concept metamorphosis was first demonstrated stepwise conversion dibenzothiophenes dibenzofurans triphenylenes. These transformations, facilitated palladium nickel catalysts, involve strategic activation robust C-S C-O bonds as key steps. Next, approach extended two-step conversions carbazoles, dibenzophospholes, fluorenes, etc., oxidation corresponding sulfones subsequent sequential inter- intramolecular nucleophilic substitution reactions. new routes have provided efficient access optoelectronic Especially, SNAr-based construction heterohelicene library systematic variation atoms. This strategy revolutionized way libraries constructed enables rapid discovery molecules.In addition substitutions, ring-expanding through insertion also been explored. We developed nickel-catalyzed boron benzofurans, generating benzoxaborins, important scaffolds for medicinal chemistry. catalytic transformation successfully scaled industrial synthesis companies, demonstrates practical utility metamorphosis. Furthermore, manganese-catalyzed lithium-metal-promoted methodologies expanded ranges heteroatoms inserted cleaved, providing methods heterocycles diversity element compositions.Reductive dilithiation thiophenes efficiently yields 1,4-dilithiobutadienes, react variety electrophiles produce series nonbiogenic heteroles, such boroles, phospholes, siloles. In principle, this method should allow sulfur readily available be replaced any is therefore considered ideal example terms chemical spaces elements.Aromatic proposes many synthons retrosynthetic disconnections that defy conventional wisdom organic synthesis. By making full use metamorphosing skeleton, can directly minimal effort time investment. Its applications span from pharmaceuticals materials science, paving paradigm design well strategy.

Language: Английский

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Ring-Expansion Strategy for α-Aryl Azahelicene Construction: Building Blocks for Optoelectronic Materials

Organic Letters, Journal Year: 2021, Volume and Issue: 23(20), P. 8056 - 8061

Published: Oct. 5, 2021

An acid-mediated rapid synthesis of α-aryl azahelicenes via C-C bond cleavage helical 9H-fluoren-9-ols is reported. The newly introduced aryl ring and pyridine moieties provide an excellent opportunity to further tune the properties azahelicences: i.e., photoluminescence. novel showcase high circularly polarized luminescence (CPL) efficiencies (4.5 × 10-3) as well CPL brightness (BCPL), reaching 7.39 M-1 cm-1, which indicates a potential application chiral emitters.

Language: Английский

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Sulfonium-aided coupling of aromatic rings via sigmatropic rearrangement

Proceedings of the Japan Academy Series B, Journal Year: 2022, Volume and Issue: 98(4), P. 190 - 205

Published: April 10, 2022

Biaryl synthesis continues to occupy a central role in chemical synthesis. From blockbuster drug molecules organic electronics, biaryls present numerous possibilities and new applications continue emerge. Transition-metal-catalyzed coupling reactions represent the gold standard for biaryl mechanistic steps, such as reductive elimination, are well established. Developing routes that exploit alternative scenarios could give unprecedented structures expand portfolio of applications. We have developed metal-free C-H/C-H couplings aryl sulfoxides with phenols afford 2-hydroxy-2'-sulfanylbiaryls. This cascade strategy consists an interrupted Pummerer reaction [3,3] sigmatropic rearrangement. Our method enables intriguing aromatic molecules, including oligoarenes, enantioenriched dihetero[8]helicenes, polyfluorobiaryls. our successes sulfoxide/phenol deeper understanding rearrangements synthesis, we established related methods, sulfoxide/aniline iodane/phenol couplings. Overall, fundamental interests underexplored mechanisms led various methods accessing important architectures.

Language: Английский

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X-ray and Optical Circular Dichroism as Local and Global Ultrafast Chiral Probes of [12]Helicene Racemization

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(38), P. 21012 - 21019

Published: Sept. 13, 2023

Chirality is a fundamental molecular property that plays crucial role in biophysics and drug design. Optical circular dichroism (OCD) well-established chiral spectroscopic probe the UV–visible regime. most commonly associated with localized center. However, some compounds such as helicenes (Figure 1) are due to their screwlike global structure. In these highly conjugated systems, electric magnetic allowed transitions distributed across entire molecule, OCD thus probes chirality. Recent advances X-ray sources, particular control of polarization spatial profiles, have enabled (XCD), which, contrast OCD, can exploit element-specific nature electronic transitions. XCD therefore more sensitive local structures, chirality probed it be referred local. During racemization helicene, between opposite helical screw handedness flip locally, making molecule globally achiral while retaining handedness. Here, we use mechanism [12]helicene model demonstrate capabilities time-dependent for chiralities, respectively. Our simulations provides an excellent molecules.

Language: Английский

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