Demethylation of aryl methyl ethers using pyridinium p-toluenesulfonate under microwave irradiation

Lamba, Mandeep; Makrandi, J. K.

doi:10.3184/030823407x255551

Cited by 3 publications

(2 citation statements)

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“…The deiodo product 5 could also be isolated (31%) as a side product. Deprotection of 4 was performed by demethylation in the presence of pyridinium chloride in NMP under MW irradiation for 7 h to give the key dendritic wedge 6 in 86% yield.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Properties of Oxygen-Linked N-Phenylcarbazole Dendrimers

Lee¹,

Leung²,

Lee

et al. 2011

Macromolecules

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A series of novel oxygen-linked N-phenylcarbazole (NPC) dendritic wedges (3−5) and triphenylamine-centered dendrimers (CBD-G0 to -G2) have been synthesized and extensively studied. The aryl−oxygen−aryl (Ar−O−Ar) linkages were established on 3,6-positions of carbazole and 4-position of N-phenyl group. UV−vis spectra revealed that the Ar−O−Ar linkage would break down the π conjugation and make NPC units manifest their individual absorption moiety. Both steady-state luminescence and fluorescence decay dynamics at room temperature and 77 K in tetrahydrofuran suggested that the transfer of energy from the carbazole wedges to the triphenylamine (TPA) core operates in CBD-G1, so that the luminescence mainly arises from the core unit. The quenching of the emission from carbazole wedges by the TPA core becomes less effective as the generation develops into CBD-G2. The oxidation potential of the NPC derivatives clearly revealed the mesomeric electron-donating effect of the oxygen atom and inductive electron-withdrawing effect of the carbazole unit. The potential gradient could be established on those triphenylamine-centered dendrimers (CBD-G1 and CBD-G2), such that the outer layer is electron-poor and the inner layer is electron-rich. It is remarkable that the HOMO level of the NPC dendrimers is as high as −5.17 eV and triplet energy level is kept above 2.85 eV. These levels of HOMO and triplet energy, together with good thermal stability and compatibility of solution processing, make NPC dendrimers ideal host materials for blue triplet emitters. Using CBD-G2 as the host material, the FIrpic-doped solution-processed light-emitting diodes were fabricated, and maximum luminous efficiency could be achieved at a record high of 24.7 cd/A at 484 cd/m 2 .

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Section: Resultsmentioning

confidence: 99%

Synthesis and Properties of Oxygen-Linked N-Phenylcarbazole Dendrimers

Lee¹,

Leung²,

Lee

et al. 2011

Macromolecules

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show abstract

“…[14][15][16]51 These include demethylation using tetramethylsilyl iodide 18 or pyridinium-based compounds. 61 Furthermore, ionic liquids have been successfully used. [62][63][64] Recently, Liu et al 65 reported a Cu 2 O-catalyzed demethylation procedure, which was conducted at 185 °C in methanol in the presence of sodium methanoate.…”

Section: Other Approachesmentioning

confidence: 99%