Visible‐Light‐Promoted CC Bond Cleavage: Photocatalytic Generation of Iminium Ions and Amino Radicals

Cai, Shunyou; Zhao, Xinyang; Wang, Xinbo; Liu, Qisong; Li, Zigang; Wang, David Zhigang

doi:10.1002/anie.201202880

Cited by 127 publications

(34 citation statements)

References 60 publications

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“…Li and Wang recently applied this cleavage reaction to 1,2-diamines, simultaneously generating two classes of synthetically useful intermediates, iminium ions (e.g., 133 , Scheme 30) and α-amino radicals (e.g., 134 , Scheme 30) [102]. The authors then exploited the synthetic utility of these two classes of intermediates.…”

Section: Reviewmentioning

confidence: 99%

The chemistry of amine radical cations produced by visible light photoredox catalysis

Hu¹,

Wang²,

Nguyen³

et al. 2013

Beilstein J. Org. Chem.

366

223

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Amine radical cations are highly useful reactive intermediates in amine synthesis. They have displayed several modes of reactivity leading to some highly sought-after synthetic intermediates including iminium ions, α-amino radicals, and distonic ions. One appealing method to access amine radical cations is through one-electron oxidation of the corresponding amines under visible light photoredox conditions. This approach and subsequent chemistries are emerging as a powerful tool in amine synthesis. This article reviews synthetic applications of amine radical cations produced by visible light photocatalysis.1977

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Section: Reviewmentioning

confidence: 99%

The chemistry of amine radical cations produced by visible light photoredox catalysis

Hu¹,

Wang²,

Nguyen³

et al. 2013

Beilstein J. Org. Chem.

366

223

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“…The formation of [M–H] + is considered to occur through protonated analyte molecules or radical ion molecules . Common UV or visible light is well known to induce photolytic degradation of alkyl amines to α ‐amino radicals through hydride abstraction on the methylene attached to nitrogen in the presence of a metal photoredox catalyst . Hence, we propose a mechanism for the production of [M–D] + using 2b as an example (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

“…Photolytic dehydrogenation of amines in the presence of transition metal photoredox catalysts to initiate organic transformation has been an active and deeply studied field in organic synthesis . The catalytic metal center triggers single‐electron transfer followed by the loss of a proton to form an α ‐amino radical.…”

Section: Introductionmentioning

confidence: 99%

“…We realize that the methylene between an aryl group and a nitrogen atom (benzylamine) may play a critical role in the dehydrogenation to produce a large amount of [M–H] + . Because the removal of the proton occurs at the α ‐methylene, we devised a method to distinguish between protons on the α ‐methylenes of N ‐benzyl and alkyl moieties. Isotopic labeling is a versatile tool that provides deep insight into the kinetics, regioselectivity and mechanisms of reactions .…”

Section: Introductionmentioning

confidence: 99%

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Dehydrogenation and dehalogenation of amines in MALDI‐TOF MS investigated by isotopic labeling

Kang

Zhou

et al. 2013

J. Mass Spectrom.

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Secondary and tertiary amines have been reported to form [M-H](+) that correspond to dehydrogenation in matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). In this investigation, we studied the dehydrogenation of amines in MALDI-TOF MS by isotopic labeling. Aliphatic amines were labeled with deuterium on the methylene of an N-benzyl group, which resulted in the formation of [M-D](+) and [M-H](+) ions by dedeuteration and dehydrogenation, respectively. This method revealed the proton that was removed. The spectra of most tertiary amines with an N-benzyl group showed high-intensity [M-D](+) and [M-H](+) ion peaks, whereas those of secondary amines showed low-intensity ion peaks. Ratios between the peak intensities of [M-D](+) and [M-H](+) greater than 1 suggested chemoselective dehydrogenation at the N-benzyl groups. The presence of an electron donor group on the N-benzyl groups enhanced the selectivity. The dehalogenation of amines with an N-(4-halobenzyl) group was also observed alongside dehydrogenation. The amino ions from dehalogenation can undergo second dehydrogenation. These results provide the first direct evidence about the position at which dehydrogenation of an amine occurs and the first example of dehalogenation of haloaromatic compounds in MALDI-TOF MS. These results should be helpful in the structural identification and elucidation of synthetic and natural molecules.

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“…The investi-gated ammonium acetate-catalyzed nitroaldol condensation is a Henry reaction followed by a condensation reaction carried out in acetic acid as depicted in Fig. 2 [30]. Except for substrate (1) and product (3) all other reagents and by-products are not UV-active and do not affect the measurement.…”

Section: Strategy For the Optimization Routinementioning

confidence: 99%

Inline Spectroscopy‐Based Optimization of Chemical Reactions Considering Dynamic Process Conditions

Trunina

Liauw

2020

Chemie Ingenieur Technik

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This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.The demand for sustainable energy sources, like biomass, solar energy, hydro and wind power, is connected to challenges like energy storage and fluctuating energy supply. Regarding the second challenge, industry has to evolve their existing processes from steady state processes to dynamic ones. This work is concerned with the conception of an inline spectroscopy-based optimization routine for chemical reactions under dynamic process conditions, which implements the search for a well applicable optimization algorithm. The studied reaction to reach this goal is a nitroaldol condensation.

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Visible‐Light‐Promoted CC Bond Cleavage: Photocatalytic Generation of Iminium Ions and Amino Radicals

Cited by 127 publications

References 60 publications

The chemistry of amine radical cations produced by visible light photoredox catalysis

The chemistry of amine radical cations produced by visible light photoredox catalysis

Dehydrogenation and dehalogenation of amines in MALDI‐TOF MS investigated by isotopic labeling

Inline Spectroscopy‐Based Optimization of Chemical Reactions Considering Dynamic Process Conditions

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