Nucleophilic Aromatic Substitution of Polyfluoroarene to Access Highly Functionalized 10-Phenylphenothiazine Derivatives

Kikushima, Kotaro; Koyama, Haruka; Kodama, Kazuki; Dohi, Toshifumi

doi:10.3390/molecules26051365

Cited by 8 publications

(4 citation statements)

References 73 publications

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“…Notably, the same compound 4 was smoothly accessible via the HDF of 2,3,4,5-tetrafluorobenzonitrile (3b), which ascertained the trifluorinated structure at the 2-, 3-, and 5-positions (Entry 3). Doubling the catalytic amount to 2 mol% led to a complete conversion and selectivity within 1 h. These results indicated that the C-F bond at the para position of the substituent was rather susceptible to the reduction [40,41]. 9b, 98 1 Standard conditions: Substrate (0.5 mmol), 1 (5.0 × 10 −3 mmol), 1,2-dimethoxyethane (2.5 mL), H2O (2.5 mL), 30 °C.…”

Section: Resultsmentioning

confidence: 87%

Regioselective Transfer Hydrogenative Defluorination of Polyfluoroarenes Catalyzed by Bifunctional Azairidacycle

Kuwata

Kayaki

2022

Organics

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The catalytic hydrodefluorination (HDF) with a bifunctional azairidacycle using HCOOK was examined for cyano- and chloro-substituted fluoroarenes, including penta- and tetrafluorobenzonitriles, tetrafluoroterephthalonitrile, tetrafluorophthalonitrile, 3-chloro-2,4,5,6-tetrafluoropyridine, and 4-cyano-2,3,5,6-tetrafluoropyridine. The reaction was performed in the presence of a controlled amount of HCOOK with a substrate/catalyst ratio (S/C) of 100 in a 1:1 mixture of 1,2-dimethoxyethane (DME) and H2O at an ambient temperature of 30 °C to obtain partially fluorinated compounds with satisfactory regioselectivities. The C–F bond cleavage proceeded favorably at the para position of substituents other than fluorine, which is in consonance with the nucleophilic aromatic substitution mechanism. In the HDF of tetrafluoroterephthalonitrile and 4-cyano-2,3,5,6-tetrafluoropyridine, which do not contain a fluorine atom at the para position of the cyano group, the double defluorination occurred solely at the 2- and 5-positions, as confirmed by X-ray crystallography. The HDF of 3-chloro-2,4,5,6-tetrafluoropyridine gave preference to the C–F bond cleavage over the C–Cl bond cleavage, unlike the dehalogenation pathway via electron-transfer radical anion fragmentation. In addition, new azairidacycles with an electron-donating methoxy substituent on the C–N chelating ligand were synthesized and served as a catalyst precursor (0.2 mol%) for the transfer hydrogenative defluorination of pentafluoropyridine, leading to 2,3,5,6-tetrafluoropyridine with up to a turnover number (TON) of 418.

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Section: Resultsmentioning

confidence: 87%

Regioselective Transfer Hydrogenative Defluorination of Polyfluoroarenes Catalyzed by Bifunctional Azairidacycle

Kuwata

Kayaki

2022

Organics

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“…The electron-deficient PFB component also enhances the molecule’s susceptiveness to nucleophiles and is highly amenable to S N Ar reactions . Fluorine substitution reaction through nucleophilic substitution reaction is noticed in various compounds such as pentafluorobenzaldehyde, pentafluorobenzonitrile, octafluorotoluene, pentafluorophenol-substituted porphyrins, , pentafluorophenyl ester, − pentafluoropyridine, and pentafluorobiphenyl …”

Section: Introductionmentioning

confidence: 99%

Pentafluorobenzene: Promising Applications in Diagnostics and Therapeutics

Nair,

Seo,

Hong

et al. 2023

ACS Appl. Bio Mater.

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Pentafluorobenzene (PFB) represents a class of aromatic fluorine compounds employed exclusively across a spectrum of chemical and biological applications. PFBs are credited with developing various chemical synthesis techniques, networks and biopolymers, bioactive materials, and targeted drug delivery systems. The first part of this review delves into recent developments in PFB-derived molecules for diagnostic purposes. In the latter segment, PFB's role in the domain of theragnostic applications is discussed. The review elucidates different mechanisms and interaction strategies applied in leveraging PFBs to formulate diagnostic and theragnostic tools, substantiated by proper examples. The utilization of PFBs emerges as an enabler, facilitating manifold reactions, improving materials' properties, and even opening avenues for explorative research.

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“…Diphenylamino, phenothiazinyl, phenoxazinyl, carbazolyl, and 9,9-dimethylacridinyl groups have been widely used as efficient aromatic and amino donor substituents in the molecular design of advanced D–A dyes. However, regarding the acceptor site, many reports have revealed that the introduction of fluorine atoms onto the aromatic ring of the D–A dyes using groups such as perfluorophenyl, cyano-substituted perfluorophenyl, or perfluorobiphenyl at the acceptor site instead of phenyl, substituted phenyl, or naphthyl groups is efficient for stabilizing the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and for ICT (Figure ).…”

Section: Introductionmentioning

confidence: 99%

Design, Regioselective Synthesis, and Photophysical Properties of Perfluoronaphthalene-Based Donor–Acceptor–Donor Fluorescent Dyes

et al. 2022

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A one-step route to a series of perfluoronaphthalene-based donor (D)−acceptor (A)−D fluorescent dyes with various electron-donating groups was developed. The perfluoronaphthalene moiety in the D−A−D dyes served as a good electron-accepting aromatic ring with excellent intramolecular charge transfer properties, as determined by density functional theory calculations and measurements of the fluorescence properties in solution, in poly(methyl methacrylate) (PMMA) films, and in crystal form. Notably, replacing the naphthalene ring with perfluoronaphthalene in the D−A−D dyes carrying the phenothiazine moiety not only stabilized the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels but also reduced the energy band gap to change the emission color from blue to yellow. Among the four synthesized perfluoronaphthalene D−A−D dyes, those bearing diphenylamino groups afforded the best fluorescence quantum yields in Et 2 O solution (0.60) and in PMMA film (0.65) because the propeller structure of the diphenylamino group that acts as a donor substituent effectively suppresses radiation-free deactivation. In contrast, in the crystalline state, the carbazoyl-bearing D−A−D dye provided the best fluorescence quantum yield (0.35) because the radiation-free inactivation was suppressed by π−π F stacking at the donor site, which was confirmed by single-crystal X-ray analysis.

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Nucleophilic Aromatic Substitution of Polyfluoroarene to Access Highly Functionalized 10-Phenylphenothiazine Derivatives

Cited by 8 publications

References 73 publications

Regioselective Transfer Hydrogenative Defluorination of Polyfluoroarenes Catalyzed by Bifunctional Azairidacycle

Regioselective Transfer Hydrogenative Defluorination of Polyfluoroarenes Catalyzed by Bifunctional Azairidacycle

Pentafluorobenzene: Promising Applications in Diagnostics and Therapeutics

Design, Regioselective Synthesis, and Photophysical Properties of Perfluoronaphthalene-Based Donor–Acceptor–Donor Fluorescent Dyes

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