Organic Synthesis Enabled by Light-Irradiation of EDA Complexes: Theoretical Background and Synthetic Applications

Lima, Carolina G. S.; Lima, Thiago M.; Duarte, Marcelo; Jurberg, Igor D.; Paixão, Márcio W.

doi:10.1021/acscatal.5b02386

Cited by 571 publications

(367 citation statements)

References 160 publications

(147 reference statements)

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“…The combination of 1, 2 , and TFAA (1:1:2 ratio; Figure 2A) revealed a strongly absorbing signal in the visible region, and we postulated that this new absorbance could be attributed to an electron donor-acceptor (EDA) interaction. 71 To probe this relationship further, we measured the absorbance profile of the acylated reagent with a number of electron-rich arenes of known ionization potential ( I p ), including naphthalene ( I p = 8.12 eV), 72 1,3,5-trimethoxybenzene ( I p = 7.96 eV), 73 and 2-methoxynaphthalene ( I p = 7.80 eV). 74 EDA complexes have a characteristically linear relationship between their charge-transfer absorbance energy (hν CT ∝ λ max ) and the ionization potential ( I p ) of the constituent donor.…”

Section: Resultsmentioning

confidence: 99%

Photochemical Perfluoroalkylation with Pyridine N -Oxides: Mechanistic Insights and Performance on a Kilogram Scale

Beatty

Douglas

Miller

et al. 2016

Chem

242

160

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SUMMARY The direct trifluoromethylation of (hetero)arenes is a process of high importance to the pharmaceutical industry. Many reagents exist for this purpose and have found widespread use in discovery efforts; however, the step-intensive preparation of these reagents and their corresponding cost have resulted in minimal use of these methods in large-scale applications. For the ready transition of direct trifluoromethylation methodologies to large-scale application, the further development of processes utilizing inexpensive CF3 sources available on a metric ton scale is highly desirable. We report the use of pyridine N-oxide derivatives in concert with trifluoroacetic anhydride to promote a high-yielding and scalable trifluoromethylation reaction. Key mechanistic insights include the observation of electron donor-acceptor complexes in solution as well as a high dependence on photon flux. These observations have culminated in the application of this chemistry on a kilogram scale, demonstrating the utility of this reagent combination for preparative applications.

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Section: Resultsmentioning

confidence: 99%

Photochemical Perfluoroalkylation with Pyridine N -Oxides: Mechanistic Insights and Performance on a Kilogram Scale

Beatty

Douglas

Miller

et al. 2016

Chem

242

160

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“…[38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] We have also explored photoredox catalysis employing photofunctional complexes of Ru II ,I r III ,a nd Pt II ,a nd established the photoelectrochemical mechanismso ft he reductive actions of such complexes. Radical species canb ed erived from benzylh alidest hrough photoinduced reductived issociation.…”

Section: Introductionmentioning

confidence: 99%

Mechanism and Applications of the Photoredox Catalytic Coupling of Benzyl Bromides

Park

Jung

et al. 2016

Chemistry A European J

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The photoredox catalytic coupling of halomethyl arenes to bibenzyl derivatives has been demonstrated. The catalytic protocol employed the Hantzsch ester, potassium phosphate, and a photoactive cyclometalated Ir complex catalyst. A photochemical quantum yield as high as 20 % was obtained. The catalytic mechanism was investigated in detail by performing photophysical and electrochemical measurements, as well as by quantum chemical calculations. The results suggest that two-electron mediation might be responsible for the improved photon economy. The reaction protocol was compatible with halomethyl arenes that contain a variety of functional groups. Finally, the synthetic utility of our protocol was demonstrated by the preparation of a natural dihydrostilbenoid, brittonin A.

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“…11 Further studies revealed that white LED irradiation, the presence of base, and the absence of oxygen were each essential for this transformation (entries 2, 5, and 6). These control experiments suggest a radical mechanism involving thiyl and aryl radicals formed as a result of visible-light-promoted intermolecular charge transfer 12 that are subsequently quenched to yield the C–S cross-coupled product (vide infra).…”

mentioning

confidence: 99%

Visible-Light-Promoted C–S Cross-Coupling via Intermolecular Charge Transfer

2017

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Disclosed is a mild, scalable, visible-light-promoted cross-coupling reaction between thiols and aryl halides for the construction of C–S bonds in the absence of both transition metal and photoredox catalysts. The scope of aryl halides and thiol partners includes over 60 examples and therefore provides an entry point into various aryl thioether building blocks of pharmaceutical interest. Furthermore, to demonstrate its utility, this C–S coupling protocol was applied in drug synthesis and late-stage modifications of active pharmaceutical ingredients. UV–vis spectroscopy and time-dependent density functional theory calculations suggest that visible-light-promoted intermolecular charge transfer within the thiolate–aryl halide electron donor–acceptor complex permits the reactivity in the absence of catalyst.

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Organic Synthesis Enabled by Light-Irradiation of EDA Complexes: Theoretical Background and Synthetic Applications

Cited by 571 publications

References 160 publications

Photochemical Perfluoroalkylation with Pyridine N -Oxides: Mechanistic Insights and Performance on a Kilogram Scale

Photochemical Perfluoroalkylation with Pyridine N -Oxides: Mechanistic Insights and Performance on a Kilogram Scale

Mechanism and Applications of the Photoredox Catalytic Coupling of Benzyl Bromides

Visible-Light-Promoted C–S Cross-Coupling via Intermolecular Charge Transfer

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