Transition‐Metal‐Free Intramolecular Ullmann‐Type O‐Arylation: Synthesis of Chromone Derivatives

Zhao, Jie; Zhao, Yufen; Fu, Hua

doi:10.1002/anie.201007302

Cited by 102 publications

(35 citation statements)

References 74 publications

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“…Flavonoids play a vital role in plants as secondary metabolites [10]. Chromone serves as a key scaffold in synthetic organic chemistry [11], medicinal chemistry [12], and drug discovery [13]. In solution, simple chromones may undergo photodimerizations and photoaddition reactions [14] with olefins and acetylenes.…”

Section: Introductionmentioning

confidence: 99%

Modulating the reactivity of chromone and its derivatives through encapsulation in a self-assembled phenylethynylene bis-urea host

Salpage

Donevant

Smith

et al. 2016

Journal of Photochemistry and Photobiology A: Chemistry

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A B S T R A C TThis manuscript reports on the modulation of the photoreactivity of a series of chromones, also known as benzo-g-pyrones, by absorption into a porous self-assembled host formed from phenylethynylene bisurea macrocycles. Chromone and four derivatives namely 6-fluorochromone, 6-bromochromone, 7-hydroxy-4-chromone, and 3-cyanochromone are unreactive in the solid-state. Each of these derivatives was loaded into the nanochannels of self-assembled phenylethynylene bis-urea macrocycles to form solid hostÁguest complexes, which were subsequently UV-irradiated at room temperature under argon atmosphere. We observed that chromone and 6-fluorochromone underwent selective [2 + 2] photodimerization reactions to produce anti-HT dimers in high selectivity and conversion. The 6-bromochromone also reacted in high selectivity and conversion to afford an aryl coupling adduct. In each case, the products were extracted, and the crystalline host recovered. In comparison, 7-hydroxy-4-chromone, and 3-cyanochromone were unreactive within the complex. Simple GCMC simulation studies suggest that chromone, 6-fluorochromone, and 6-bromochromone were loaded in orientations that facilitate photoreaction, and correctly predicted that the anti-HT dimer would be favored in the chromone case. In contrast, syn-HH dimers were predicted by GCMC simulations for the halogen containing derivatives but were not observed. The simulations with 7-hydroxy-4-chromone were in agreement with the observed reactivity. We compare these computational and experimental findings and suggest future methods for optimizing simulation parameters. Our goal is to expand the scope and accuracy of the simulations to be able to predict the reactivity of guests encapsulated within columnar nanotubes.

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Section: Introductionmentioning

confidence: 99%

Modulating the reactivity of chromone and its derivatives through encapsulation in a self-assembled phenylethynylene bis-urea host

Salpage

Donevant

Smith

et al. 2016

Journal of Photochemistry and Photobiology A: Chemistry

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“…[1b,h, 3, 4] In general, alkylboron compounds can be accessed by four different methods: 1) nucleophilic reaction by Grignard [5] or organolithium reagents [6] with suitable boron compounds, such as BX 3 (X = Cl, F) or B(OR) 3 ; 2) hydroboration of alkenes; [3,7,8] 3) Miyaura borylation; [9][10][11] 4) transition-metalcatalyzed borylation of alkanes by C À H bond activation. [14] Recently, significant progress has been made in the development of metal-free transformations to form C À C, [15] C À O, [16] C À N, [17] C À S, [18] and C À B [19] bonds. However, a common requirement is that metals, either as catalysts or in stoichiometric amounts, have to be used.…”

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confidence: 99%

Transition‐Metal‐Free Synthesis of Pinacol Alkylboronates from Tosylhydrazones

Wang

Zhang

et al. 2012

Angewandte Chemie

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“…CuBr, CuCl, Cu(OAc) 2 , CuO, and CuSO 4 were found to be efficient catalysts for the tandem C-S/C-N reactions, while CuI gave the best result (Table 1, entries 1-7). In view of recent advances in transition-metalfree reactions [4][5][6][7][8][9][10][11][12][13][14][15], we intentionally performed this reaction without any copper salt as catalyst, and we surprisingly found that the desired product was also obtained ( Table 1, entry 8). We then changed K 2 CO 3 to Na 2 CO 3 , but lower yield was encountered (Table 1, entry 9).…”

Section: Resultsmentioning

confidence: 94%

“…Early in 2001, Beller first reported a transition-metalfree intra-and intermolecular C-N coupling with aryl chlorides with primary and secondary amines as substrates [4]. Thereafter, a great number of C-X coupling reactions have been developed into transition-metal-free reactions [5][6][7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 98%

Transition-metal-free synthesis of imidazobenzothiazines via domino C-S/C-N bond formation

Zhou

et al. 2014

Monatsh Chem

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The carbon-heteroatom bond formation is an important research field. Transition-metal-free synthesis of medicinally important heterocycles avoids products of transition metal contamination, and thus it is an environmentally friendly and cost-saving process. A transitionmetal-free domino C-S/C-N formation for the synthesis of imidazobenzothiazines from 2-mercaptobenzimidazoles and 2-halobenzyl bromides is developed. The desired products were obtained in good to excellent yields. The mechanism of domino nucleophilic substitution (S N 2) and nucleophilic aromatic substitution (S N Ar) is proposed.

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Transition‐Metal‐Free Intramolecular Ullmann‐Type O‐Arylation: Synthesis of Chromone Derivatives

Cited by 102 publications

References 74 publications

Modulating the reactivity of chromone and its derivatives through encapsulation in a self-assembled phenylethynylene bis-urea host

Modulating the reactivity of chromone and its derivatives through encapsulation in a self-assembled phenylethynylene bis-urea host

Transition‐Metal‐Free Synthesis of Pinacol Alkylboronates from Tosylhydrazones

Transition-metal-free synthesis of imidazobenzothiazines via domino C-S/C-N bond formation

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