6 research outputs found
Metal-Free Tandem Beckmann–Electrophilic Aromatic Substitution Cascade Affording Diaryl Imines, Ketones, Amines, and Quinazolines
A cascade reaction sequence involving a Beckmann rearrangement on benzophenone oxime followed by an electrophilic aromatic substitution (EAS) on the intermediate nitrilium ion affords N-phenyl diaryl imines that may then be hydrolyzed to ketones, or reduced to the corresponding amines. Reaction with benzonitrile afforded 2,4-diphenylquinazoline through a Beckmann–Ritter–EAS cascade
Rearrangement of Cyclotriveratrylene (CTV) Diketone: 9,10-Diarylanthracenes with OLED Applications
Electroluminescent 9,10-diaryl anthracenes have been shown to be promising host and hole-transporting materials in organic electroluminescence due to their high thermal stability, electrochemical reversibility, and wide band gap useful for organic light-emitting diodes (OLEDs), especially blue OLEDs. Oxidation of cyclotriveratrylene (CTV) to the corresponding diketone and subsequent bromination resulted in an unexpected rearrangement to a highly functionalized 9-aryl-10-bromoanthracene derivative, which was employed in Suzuki couplings to synthesize a series of 9,10-diaryl compounds that are structural analogues of anthracene derivatives used in the preparation of OLEDs but are more highly functionalized, including electron-donating methoxy groups in addition to substitution by a carboxylic acid moiety. The UV/fluorescence solution spectra show strong emissions at 446, 438, and 479 nm, respectively, for the anthracene 10-phenyl, 10-naphthyl, and 10-pyrenyl adducts containing a benzoic acid functional group, whereas the analogues bearing the hydroxymethylene moiety from reduction of the benzoic acid to the corresponding alcohols gave much shorter emission wavelengths of 408, 417, and 476 nm, respectively, and had somewhat higher quantum yields, suggesting they are better candidates for OLED applications
Synthesis, Crystal Structure, and Rearrangements of ortho-Cyclophane Cyclotetraveratrylene (CTTV) tetraketone
Oxidation of cyclotetraveratrylene (CTTV) with potassium permanganate in pyridine under reflux gave tetraketone (the [14]ketonand) 3 which exists as a previously unobserved barrel conformation with S4symmetry in the crystal structure, although the more familiar ‘boat’ conformer was shown by semi-empirical AM1 calculations to be 3.03 kcal/mol lower in energy. In addition to CTTV tetraketone 3, an isomeric bis-spirolactone 4 was isolated from the basic oxidation conditions, analogous to the product of trans-annular attack and rearrangement observed with oxidation of cyclotriveratrylene, whereas in acid at elevated temperatures, tetraketone 3 underwent a very efficient rearrangement and decarboxylation to afford the highly symmetric spirobi[anthracene]-10,10′-dione derivative 5
Rearrangement of Cyclotriveratrylene (CTV) Diketone: 9,10-Diarylanthracenes with OLED Applications
Electroluminescent 9,10-diaryl anthracenes have been
shown to be
promising host and hole-transporting materials in organic electroluminescence
due to their high thermal stability, electrochemical reversibility,
and wide band gap useful for organic light-emitting diodes (OLEDs),
especially blue OLEDs. Oxidation of cyclotriveratrylene (CTV) to the
corresponding diketone and subsequent bromination resulted in an unexpected
rearrangement to a highly functionalized 9-aryl-10-bromoanthracene
derivative, which was employed in Suzuki couplings to synthesize a
series of 9,10-diaryl compounds that are structural analogues of anthracene
derivatives used in the preparation of OLEDs but are more highly functionalized,
including electron-donating methoxy groups in addition to substitution
by a carboxylic acid moiety. The UV/fluorescence solution spectra
show strong emissions at 446, 438, and 479 nm, respectively, for the
anthracene 10-phenyl, 10-naphthyl, and 10-pyrenyl adducts containing
a benzoic acid functional group, whereas the analogues bearing the
hydroxymethylene moiety from reduction of the benzoic acid to the
corresponding alcohols gave much shorter emission wavelengths of 408,
417, and 476 nm, respectively, and had somewhat higher quantum yields,
suggesting they are better candidates for OLED applications