Construction of Bisbenzofuro[2,3-<i>b</i>:3′,2′-<i>e</i>]pyridines by Palladium-Catalyzed Double Intramolecular Oxidative C–H/C–H Coupling

Kaida, Hiroyuki; Goya, Tsuyoshi; Nishii, Yuji; Hirano, Koji; Satoh, Tetsuya; Miura, Masahiro

doi:10.1021/acs.orglett.7b00323

Cited by 28 publications

(42 citation statements)

References 36 publications

(14 reference statements)

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“…When compared with non-substituted BBZFPy, 6 the Stokes shift is much larger (6547 cm -1 for 4aa, 1041 cm -1 for BBZFPy), which is typical to the emissions from the singlet charge-transfer excited state ( 1 CT) of D-A type conjugated compounds. In fact, distinct positive-solvatochromism of the emissions were observed with a D-A compound 4hc, which has an electron-withdrawing group (CF 3 )…”

Section: Steady-state Photophysical Propertiesmentioning

confidence: 94%

“…To synthesize precursors for D-A-type BBZFPys and to verify the generality of the previously developed oxidative C-H/C-H coupling, diaryloxypyridines 2 were subjected to the slightly modified coupling reaction conditions (Table 1). 6 In the presence of Pd(TFA) 2 as a catalyst and AgOAc as a stoichiometric oxidant, p-chlorinated diphenoxypyridine 2a smoothly underwent the double C-H/C-H coupling to give monochlorinated BBZFPy product 3a in a good yield (80%).…”

Section: Scheme 1 Preparation Of Unsymmetric Chloro-bearing 26-diarmentioning

confidence: 99%

“…Typically, in CHCl 3 solutions, almost all the compounds exhibited an absorption at around 290 nm and structured absorptions ranging from 330 nm to 380 nm (Figure 2a, c, e, g, and i), which are very similar to that of non-substituted BBZFPy. 6 Upon the irradiation of UV light, all the compounds are emissive in solution in violet-to-green region, with the PLQYs ranging from 0.01 to 0.71 (Table 3).…”

Section: Steady-state Photophysical Propertiesmentioning

confidence: 99%

“…1.52 g, 72%, colorless oil; Spectroscopy data were in good agreement with those reported previously. 6 Prepared by following a general procedure on a 11.5 mmol scale (1b). Purified by column chromatography (eluent n-hex/AcOEt 20:1) on silica gel followed by GPC (CHCl 3 ).…”

Section: General Procedures For the Preparation Of 2-bromo-6-aryloxypymentioning

confidence: 99%

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Syntheses of Diverse Donor-Substituted Bisbenzofuro[2,3-b:3′,2′-e]pyridines (BBZFPys) via Pd Catalysis, and Their Photophysical Properties

et al. 2018

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A series of bisbenzofuro[2,3- b:3',2'- e]pyridines (BBZFPys) bearing a chlorine functionality have been efficiently synthesized through a Pd-catalyzed double oxidative intramolecular C-H/C-H coupling of monochlorinated 2,6-diaryloxypyridines. The subsequent Buchwald-Hartwig amination of the chlorinated BBZFPys allowed for the access to a new class of donor-acceptor (D-A) π-conjugated compounds that comprise BBZFPy as an electron acceptor (A) and diarylamines as a donor (D) unit. The investigation of the steady-state photophysical properties of the prepared D-A compounds revealed that they are emissive in both solution and solid states in the blue-to-green color region. The singlet-triplet energy splitting (Δ E) was found to be much smaller than that of substituent-free BBZFPy (0.70 eV), ranging from 0.01 to 0.56 eV. The time-resolved spectroscopy revealed that the D-A compounds, comprising a bis( tert-butyl)carbazole as the D and CF-attached BBZFPy as the A, showed delayed fluorescence (DF) in nonpolar matrix host material (Zeonex), while in a polar matrix (DPEPO), room-temperature phosphorescence (RTP) was faintly observed. Furthermore, organic light-emitting diodes (OLEDs) fabricated with the D-A compounds as a blue emitter showed a moderate external quantum efficiencies (EQEs) up to 1.5%.

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Section: Steady-state Photophysical Propertiesmentioning

confidence: 94%

Section: Scheme 1 Preparation Of Unsymmetric Chloro-bearing 26-diarmentioning

confidence: 99%

Section: Steady-state Photophysical Propertiesmentioning

confidence: 99%

Section: General Procedures For the Preparation Of 2-bromo-6-aryloxypymentioning

confidence: 99%

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Syntheses of Diverse Donor-Substituted Bisbenzofuro[2,3-b:3′,2′-e]pyridines (BBZFPys) via Pd Catalysis, and Their Photophysical Properties

et al. 2018

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“…We have been interested in the synthesis of polycondensed heteroaromatic systems and recently disclosed palladium‐catalyzed methods for the construction of derivatives of BTBT and higher homologs,– oxygen‐containing BTBT analogs, benzo‐bis‐ and benzo‐tris‐benzofurans, and bisbenzofuropyridines ,. It was of considerable interest to observe that among the latter compounds, 2,8‐di‐ tert ‐substituted bisbenzofuro[2,3‐ b : 3′,2′‐ e ]pyridine 1 a showed a largely red‐shifted broad peak at 426 nm in the solid state fluorescence spectrum, whereas a relatively sharp peak at 380 nm was observed in the case of its 3,9‐di‐ tert ‐butyl isomer 1 b (Scheme , see the Supporting Information) ,. This appears to be attributable to their different crystal packing patterns.…”

Section: Introductionmentioning

confidence: 99%

Effect of Substitution Pattern of tert‐Butyl Groups in a Bisbenzofuropyrazine Core π‐System on Optical Properties: Unique Mechanochromic Fluorescence Behavior

Nakamura

Tohnai

Nishii³

et al. 2018

ChemPhotoChem

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Bisbenzofuro[2,3‐b : 2′,3′‐e]pyrazine (BBFPy) and its 2,8‐ and 3,9‐di(tert‐butyl)‐substituted derivatives (2 a and 2 b) were synthesized by palladium‐catalyzed intramolecular direct arylation as the key step. The effect of introduction of two tert‐butyl groups to the BBFPy core at the different positions on the fluorescent properties was then investigated. The tert‐butyl groups not only enhance the tractability with increasing solubility, but also induce different crystal‐packing patterns as anticipated. The compounds 2 a and 2 b show relatively strong blue fluorescence in both the solution and solid state. The 2,8‐isomer 2 a specifically exhibits a unique mechanochromism in the solid state; 2 a exhibits two crystalline forms, both of which show green fluorescence by grinding, while different self‐recovering fluorescence patterns between them are observed by standing. The intriguing mechanochromism is rationally interpreted in terms of molecular arrangements determined by X‐ray crystallography.

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Red and Near Infrared Emissive Bis‐Tridentate Ir(III) Phosphors for Organic Light Emitting Diodes

Yan,

Song,

Zhou

et al. 2023

Advanced Optical Materials

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Efficient saturated red and near‐infrared (NIR) emissive materials are needed in the development of organic light‐emitting diodes (OLEDs), with applications extending beyond flat panel displays and lighting luminaries. Toward this aim, a series of bis‐tridentate Ir(III) complexes (3a ‒ 3c and 4a ‒ 4c) are designed and synthesized, showing emission spanning the region of 601‒694 nm in degassed toluene. Their emission tuning is mainly achieved using monoanionic chromophoric chelates, L1H for red and L2H for deep‐red and NIR, where the extended π‐conjugation and electron deficient N atoms are introduced synergistically. Moreover, three ancillary chelates, X1H2, X2H2, and X3H2, delivered a secondary influence via varied donor strength to the central Ir(III) atom. The resulting red and deep‐red OLED devices exhibit maximum (max.) external quantum efficiencies (EQEs) of 21.4% and 18.1% with peak maximum at 620 and 666 nm, respectively. More impressively, the device based on 4b delivers a NIR emission peak maximum at 702 nm with a maximum EQE of 10.0%.

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Construction of Bisbenzofuro[2,3-b:3′,2′-e]pyridines by Palladium-Catalyzed Double Intramolecular Oxidative C–H/C–H Coupling

Cited by 28 publications

References 36 publications

Syntheses of Diverse Donor-Substituted Bisbenzofuro[2,3-b:3′,2′-e]pyridines (BBZFPys) via Pd Catalysis, and Their Photophysical Properties

Syntheses of Diverse Donor-Substituted Bisbenzofuro[2,3-b:3′,2′-e]pyridines (BBZFPys) via Pd Catalysis, and Their Photophysical Properties

Effect of Substitution Pattern of tert‐Butyl Groups in a Bisbenzofuropyrazine Core π‐System on Optical Properties: Unique Mechanochromic Fluorescence Behavior

Red and Near Infrared Emissive Bis‐Tridentate Ir(III) Phosphors for Organic Light Emitting Diodes

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