Dehalogenation reaction photocatalyzed by homoleptic copper(<scp>i</scp>) complexes associated with strongly reductive sacrificial donors

Gimeno, Léa; Queffélec, Clémence; Haidaraly, Kevin Mall; Blart, Errol; Pellegrin, Yann

doi:10.1039/d1cy01209f

Cited by 15 publications

(34 citation statements)

References 41 publications

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“…The general procedure described in the experimental section was followed, and results are summarized in Table 3. with those reported in the literature, the 13 C NMR spectra of such compounds often displayed fewer peaks than anticipated, even when taking into account free rotation around the bond to the C-2 aryl substituent and rapid tautomerization of the benzimidazole. We therefore sought further proof of structure for at least one representative compound.…”

Section: Scheme 3 Nitration Of 14-dimethoxybenzenesupporting

confidence: 63%

“…11 More recently, Corma, Sorribes, and coworkers have described the synthesis of benzimidazoles by reaction of o-dinitrobenzene derivatives with aldehydes under catalytic hydrogenation conditions. 12 One example of treatment of an o-dinitrobenzene derivative with sodium dithionite in the presence of an aldehyde to yield a benzimidazole has been reported by Queffelec, Pellegrin and coworkers, 13 but required 10 days of heating the reaction mixture at reflux. Use of sodium dithionite in other reductive cyclizations has also been reported.…”

Section: Scheme 2 Synthesis Of 47-dimethoxybenzimidazolesmentioning

confidence: 99%

“…Evaporation of solvent from a dichloromethane solution of pyridyl-substituted benzimidazole (2f) produced a collection of crystals from which structural information was obtained by means of X-ray crystallography, verifying the structure of this compound (see Supporting Information). It was later determined that obtaining 13 C NMR spectra in pure CD3OD or mixtures of CD3OD and DMSO-d6 allowed the expected number of peaks to be observed in all but one case. 16 Use of this method to prepare benzimidazole (2i) (R = H), which has been prepared by heating 1 at reflux in 98% formic acid, 10 was also investigated.…”

Section: Scheme 3 Nitration Of 14-dimethoxybenzenementioning

confidence: 99%

“…2a 12 1 H NMR (CDCl3): δ 8.11 (dd, J = 8.0, 1.8 Hz, 2H), 7.5-7.2 (m, 3H), 6.57 (s, 2H), 3.93 (s, 6H). 13 C NMR (CD3OD and DMSO-d6): δ 149. 2, 141.7, 130.4, 128.4, 127.3, 126.8, 126.7, 103.5, 54.8. 2b 15 1 H NMR (CDCl3): δ 8.42 (dd, J = 7.9, 1.7 Hz, 1H), 7.65 (dd, J = 8.0, 1.0 Hz, 1H), 7.5-7.4 (m, 1H), 7.3-7.2 (m, 1H), 6.60 (s, 2H), 3.97 (s, 6H).…”

Section: Compound Characterization Datamentioning

confidence: 99%

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Facile Protocol for the Synthesis of Electron-Rich Benzimidazole Derivatives

Love¹,

Pike²

2022

HETEROCYCLES

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A protocol is reported which allows preparation of electron-rich benzimidazole derivatives in good yield. The reaction proceeds directly from dinitrobenzene derivatives without need of isolation of air-sensitive diamines.Benzimidazole-4,7-diones (3) are compounds of interest due to their potential use as anticancer and antifungal agents. [1][2][3][4][5][6][7][8] They are typically prepared by oxidation of the corresponding 4,7-dimethoxybenzimidazoles (2), which in turn are prepared from 3,6-dimethoxybenzene-1,2-diamine (1) (Scheme 1). Both aldehydes 1,2,7,8 and carboxylic acids 7,9,10 have been used for this reaction, with the former requiring oxidation of one of the intermediates, which is often accomplished simply by exposure to air. Scheme 1. Synthesis of benzimidazole-4,7-dionesAs part of another project, we were interested in preparing benzimidazole derivatives 2 by a simple and convenient method. Previous reports describing the synthesis of 3,6-dimethoxybenzene-1,2-diamine 1 have noted its significant air sensitivity, 9,10 which makes working with the compound somewhat

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Section: Scheme 3 Nitration Of 14-dimethoxybenzenesupporting

confidence: 63%

Section: Scheme 2 Synthesis Of 47-dimethoxybenzimidazolesmentioning

confidence: 99%

Section: Scheme 3 Nitration Of 14-dimethoxybenzenementioning

confidence: 99%

Section: Compound Characterization Datamentioning

confidence: 99%

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Facile Protocol for the Synthesis of Electron-Rich Benzimidazole Derivatives

Love¹,

Pike²

2022

HETEROCYCLES

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“…Interestingly, there have been fewer reports where the excited state of a homoleptic copper(I) complex [CuL 2 ] + * is reductively quenched by an electron donor. 8 This is explained by the very weak oxidative power of [CuL 2 ] + *, a common feature of all traditional homoleptic copper(I) complexes. 8a , 8b , 9 …”

Section: Introductionmentioning

confidence: 99%

Copper(I) Bis(diimine) Complexes with High Photooxidation Power: Reductive Quenching of the Excited State with a Benzimidazoline Sacrificial Donor

et al. 2022

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The reductive quenching of photoexcited photosensitizers is a very efficient way to achieve challenging reduction reactions. In this process, the excited photosensitizer is reduced by a sacrificial electron donor. This mechanism is rarely observed with copper(I) bis(diimine) complexes, which are nevertheless acknowledged as very promising photosensitizers. This is due to the fact that they are very poor photooxidants and prove unable to react with common donors once promoted in their excited state. In this article, we evidence the rare reductive quenching cycle with two specially designed copper(I) complexes. These complexes exhibit improved photooxidation power thanks to an optimized coordination sphere made of strongly π-accepting ligands. Reductive quenching of the excited state of the latter complexes with a classical benzimidazoline sacrificial donor is monitored, and reduced complexes are accumulated during prolonged photolysis. Trials to utilize the photogenerated reductive power are presented.

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Interplay of electronic and geometric structure on Cu phenanthroline, bipyridine and derivative complexes, synthesis, characterization, and reactivity towards oxygen

Romo

Reis

Nascimento

et al. 2023

Coordination Chemistry Reviews

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Dehalogenation reaction photocatalyzed by homoleptic copper(i) complexes associated with strongly reductive sacrificial donors

Abstract: In order to perform challenging reduction reactions with light, at low cost and low toxicity, we aim at using for the first time a reductive quenching cycle with a simple,...

Cited by 15 publications

References 41 publications

Facile Protocol for the Synthesis of Electron-Rich Benzimidazole Derivatives

Facile Protocol for the Synthesis of Electron-Rich Benzimidazole Derivatives

Copper(I) Bis(diimine) Complexes with High Photooxidation Power: Reductive Quenching of the Excited State with a Benzimidazoline Sacrificial Donor

Interplay of electronic and geometric structure on Cu phenanthroline, bipyridine and derivative complexes, synthesis, characterization, and reactivity towards oxygen

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