Six-Membered Ring Systems

Miller, Michael M.; DelMonte, Albert J.

doi:10.1016/b978-0-08-096805-6.00013-9

Cited by 12 publications

(1 citation statement)

References 199 publications

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“…In the case of an essential electron-donor 9 H -carbazole, the electron pair on the nitrogen atom participates in electron delocalization, inducing the appearance of negative charges on carbon atoms, thus bearing the electron-donating ability of the compound . In contrast, the lone electron pairs of nitrogen atoms of pyrimidine and triazine are in the equatorial position to the ring that constrains them from being involved in π-conjugation and causes the appearance of partly positive charges on carbon atoms. , This makes them favorable acceptor constituents in the design of donor–acceptor (D–A)-type electroactive compounds. Moreover, in nitrogen-containing heterocycles, triplet states with n π* character are present, which facilitates intersystem crossing, thus increasing the intensity of delayed fluorescence .…”

Section: Introductionmentioning

confidence: 99%

Effects of Electron-Withdrawing Strengths of the Substituents on the Properties of 4-(Carbazolyl-R-benzoyl)-5-CF₃-1H-1,2,3-triazole Derivatives as Blue Emitters for Doping-Free Electroluminescence Devices

Stanitska,

Pokhodylo,

Lytvyn

et al. 2024

ACS Omega

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The synthesis of four 4-(carbazolyl-R-benzoyl)-5-CF 3 -1H-1,2,3-triazoles with extra groups ((3-methyl)-phenyl-, 4fluorophenyl-, quinolinyl-, or (3-trifluoromethyl)-phenyl-) in the acceptor fragment has been reported. The effects of substituents with different electron-withdrawing strengths on the thermal, electrochemical, photophysical, and electroluminescence properties of the synthesized compounds are discussed. The results of X-ray analyses and density functional theory (DFT) calculations support unusual molecular packing and electronic properties. The compounds are capable of glass formation with glass transition temperatures ranging from 54−84 °C. Ionization potentials of the compounds are in the range of 5.98−6.22 eV and electron affinities range from 3.09 to 3.35 eV. Under ultraviolet excitation, the neat films of the compounds exhibit blue emission with photoluminescence quantum yields ranging from 18 to 27%. The films of selected compounds are used for the preparation of host-free light-emitting layers of organic light-emitting diodes with very simple device structures and an external quantum efficiency of 4.6%.

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Section: Introductionmentioning

confidence: 99%

Effects of Electron-Withdrawing Strengths of the Substituents on the Properties of 4-(Carbazolyl-R-benzoyl)-5-CF₃-1H-1,2,3-triazole Derivatives as Blue Emitters for Doping-Free Electroluminescence Devices

Stanitska,

Pokhodylo,

Lytvyn

et al. 2024

ACS Omega

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Synthesis of N ‐Heterocycles via [3 + n] Cycloaddition Reactions of Vinyl Metal Carbene Intermediates

Bao¹,

Zhou²,

Xu³

2022

More Synthetic Approaches to Nonaromatic Nitrogen Heterocycles

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Highly Enantioselective Dearomatizing Formal [3+3] Cycloaddition Reactions of N‐Acyliminopyridinium Ylides with Electrophilic Enol Carbene Intermediates

Zavalij

Doyle

2013

Angewandte Chemie

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Heterocyclic compounds are widely distributed in nature, [1] and their core structures are present in a vast array of pharmaceuticals. [2] Although extensive efforts have concentrated on their syntheses, [3] including asymmetric catalytic processes, [4] the demand for greater structural diversity continues to be of intense interest. [5] In particular, there is increasing interest in the asymmetric synthesis of dihydropyridine, dihydroquinoline, dihydroisoquinoline, and related heterocycles, which are core structures in natural products and other bioactive molecules. [4a-f] However, the asymmetric synthesis of heterocyclic structures with more than one nitrogen atom is rare. [6][7][8] The use of N-iminoquinolinium ylides for the asymmetric construction of dihydroquinoline derivatives by a [3+3] cycloaddition with 1,1-cyclopropane diesters, originally reported by Charette and co-workers for the non-asymmetric version, [7e] was recently reported. [4a] Good yields and high enantiocontrol were achieved in this kinetic resolution, but high catalyst loadings of nickel(II) perchlorate and a chiral Inbis(oxazoline) ligand were required. We have been investigating the dirhodium-catalyzed 1,3-dipolar [3+3] cycloaddition with enol diazoacetates 1. [9,10] The metal/enol carbene intermediates generated by dinitrogen extrusion have electrophilic character at both the carbene and vinylogous positions, with preferential reaction occurring at the vinylogous position (Scheme 1). Could these dipolar intermediates be effective for the asymmetric construction of dihydroquinoline derivatives with N-iminoquinolinium ylides? Prior efforts have shown that enol carbene intermediates undergo [3+3] cycloaddition reactions with nitrones to form 3,6-dihydro-1,2oxazines 3 [9a] and with hydrazones to form tetrahydropyridazine derivatives 4, [9c] each by a stepwise process initiated by nucleophilic reaction at the vinylogous position, which occurs with high enantiocontrol. Unlike cycloaddition reactions with nitrones and hydrazones, however, reactions there is an energy barrier to cycloaddition with the required dearomatization with N-iminoquinolinium ylides, and for this reason it is perhaps not surprising that cycloaddition reactions with Niminopyridinium ylides have not yet been reported. We report herein that N-iminopyridinium ylides undergo efficient and highly enantioselective [3+3] cycloaddition reactions with enol diazoacetates in the presence of a chiral dirhodium catalyst.Pyridine-N-aminidines 5 a (N-acyliminopyridinium ylides) [4a, 11] are stable but reactive dipolar species. Treatment of 5 a with enol diazoacetate 1 a in the presence of a catalytic amount of rhodium(II) acetate in dichloromethane at room temperature produced the dearomatized bicyclic tetrahydropyridazine derivative 6 a (92 % isolated yield) in one step [Eq. (1), TBS = tert-butyldimethylsilyl]. This transformation is a more direct and convenient way to the tetrahydropyridazine derivatives compared to previous two-step one-pot methods from N-arylhydrazones and 1 ...

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Six-Membered Ring Systems

Cited by 12 publications

References 199 publications

Effects of Electron-Withdrawing Strengths of the Substituents on the Properties of 4-(Carbazolyl-R-benzoyl)-5-CF₃-1H-1,2,3-triazole Derivatives as Blue Emitters for Doping-Free Electroluminescence Devices

Effects of Electron-Withdrawing Strengths of the Substituents on the Properties of 4-(Carbazolyl-R-benzoyl)-5-CF₃-1H-1,2,3-triazole Derivatives as Blue Emitters for Doping-Free Electroluminescence Devices

Synthesis of N ‐Heterocycles via [3 + n] Cycloaddition Reactions of Vinyl Metal Carbene Intermediates

Highly Enantioselective Dearomatizing Formal [3+3] Cycloaddition Reactions of N‐Acyliminopyridinium Ylides with Electrophilic Enol Carbene Intermediates

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Six-Membered Ring Systems

Cited by 12 publications

References 199 publications

Effects of Electron-Withdrawing Strengths of the Substituents on the Properties of 4-(Carbazolyl-R-benzoyl)-5-CF3-1H-1,2,3-triazole Derivatives as Blue Emitters for Doping-Free Electroluminescence Devices

Effects of Electron-Withdrawing Strengths of the Substituents on the Properties of 4-(Carbazolyl-R-benzoyl)-5-CF3-1H-1,2,3-triazole Derivatives as Blue Emitters for Doping-Free Electroluminescence Devices

Synthesis of N ‐Heterocycles via [3 + n] Cycloaddition Reactions of Vinyl Metal Carbene Intermediates

Highly Enantioselective Dearomatizing Formal [3+3] Cycloaddition Reactions of N‐Acyliminopyridinium Ylides with Electrophilic Enol Carbene Intermediates

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Effects of Electron-Withdrawing Strengths of the Substituents on the Properties of 4-(Carbazolyl-R-benzoyl)-5-CF₃-1H-1,2,3-triazole Derivatives as Blue Emitters for Doping-Free Electroluminescence Devices

Effects of Electron-Withdrawing Strengths of the Substituents on the Properties of 4-(Carbazolyl-R-benzoyl)-5-CF₃-1H-1,2,3-triazole Derivatives as Blue Emitters for Doping-Free Electroluminescence Devices