Intermolecular Atom Transfer Radical Addition to Olefins Mediated by Oxidative Quenching of Photoredox Catalysts

Nguyen, John D.; Tucker, Joseph W.; Konieczynska, Marlena D.; Stephenson, Corey R. J.

doi:10.1021/ja108560e

Cited by 722 publications

(265 citation statements)

References 66 publications

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“…[6] In a fluorophore bearing a light-sensitive alkyl bromide moiety, radical reaction of the alkyl bromide with light reportedly induced ring opening and expansion of a fluorophore's π system, and correspondingly made the fluorescence turn on or spectrally shift. [7,8] Thus, photocatalytic radical reaction can be used as a new strategy to design photoactivatable fluorescent probes. Photoactivatable fluorescent probes are powerful tools for studying biological systems owing to the high spatial and temporal control afforded by light.…”

Section: Doi: 101002/adom201600227mentioning

confidence: 99%

Evolution of Rhodamine B into Near‐Infrared Dye by Phototriggered Radical Reaction and Its Application for Lysosome‐Specific Live‐Cell Imaging

Lan

Xue

Liu

et al. 2016

Advanced Optical Materials

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CommuniCationis to replace the central oxygen atom with a silicon atom. NIR fluorescent dyes based on Si−rhodamine were developed by Qian and co-workers, [23] Nagano and co-workers, [24] Johnsson and co-workers, [25] and Wu and co-workers.[26] However, these methods have some disadvantages such as harsh reaction conditions, long reaction time, use of hazardous reagents, and so on. Photochromic reaction based on azobenzenes, [27] diarylethenes, [28] and spiropyranes [29] were fully explored. However, rhodamine-based photochromic reactions were rarely reported. The first example of photochromism in a rhodamine amide was reported in the 1970s by Knauer and Gleiter, [30] but the lifetime of the ring-open state is very short; only a few milliseconds in polar solvents. [31,32] Recently, Tang reported a rhodamine B salicylaldehyde hydrazine metal complex [33] that exhibited photochromic properties with a long lifetime when forming a metal complex. However, to our knowledge, there is no report of using rhodamine derivatives as a platform to construct NIR fluorescent dyes based on a photocatalytic radical reaction.Herein, we present a new photocatalytic radical reaction mechanism that allows ring opening and expansion of rhodamine B, based on a photoactive bromoacetohydrazide compound (R-Br, Scheme 1). This mechanism expands the toolbox for constructing NIR fluorescent dyes and provides an emissive pre-and postactivated form, in which the typical fluorescence emission spectrum of rhodamine (580 nm) bathochromically shifts to around 690 nm. Compared to other photochemical processes, this radical reaction that continuously occurs and is based on R-Br can be conveniently monitored by UV or fluorescence spectroscopy. The photoinduced radical reaction was verified by means of the electron paramagnetic resonance (EPR) signal. Furthermore, the structure of the final NIR fluorescent dye was characterized by NMR and mass spectrometry. The application of R-Br in intracellular imaging was also explored.R-Br is a simple rhodamine derivative. [34] Without UV irradiation, like other rhodamine derivatives, [35] the absorption of R-Br shows nothing special. There are two characteristic absorptions for the closed-ring state of rhodamine at 274 and 312 nm, which arise from the N,N-diethyl-aniline and phenylacetamide groups of R-Br, respectively, and no absorption was observed at higher than 350 nm ( Figure S1 in the Supporting Information). The absorption at 290 nm was selected for use as the catalytic light source. With the 290 ±10 nm light irradiation, an obvious color change was observed for R-Br and was followed by change of the absorption spectrum.As shown in the inset of Figure 1, the colorless solution of R-Br (10 -4 M) in acetonitrile gradually turned brown upon

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Section: Doi: 101002/adom201600227mentioning

confidence: 99%

Evolution of Rhodamine B into Near‐Infrared Dye by Phototriggered Radical Reaction and Its Application for Lysosome‐Specific Live‐Cell Imaging

Lan

Xue

Liu

et al. 2016

Advanced Optical Materials

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“…12 The reaction is operatically simple under mild reaction conditions, which is capable of tolerating a variety of functional groups such as free alcohols, esters, ethers, silyl ethers, halides, enones, and carbamates. Additionally, perfluoroalkyl halides are good partners and could react with olefins to afford fluorinated compounds which have particular value in medicinal chemistry, agrochemicals, and material science.…”

Section: Activated Alkyl Halidesmentioning

confidence: 99%

Olefin difunctionalizations via visible light photocatalysis

Cao

Ren

2015

Tetrahedron Letters

201

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“…8 This includes aryl-aryl bond formations, as well as radical cyclizations and atom transfer radical additions. 6,9,10,11,12 Such a versatile transformation warrants the development of photocatalytic systems that can chemoselectively activate carbon-halogen bonds (C-X), giving potential for taking a single synthetic derivative bearing multiple C-X bonds and synthesizing a large library of complex targets.…”

Section: Introductionmentioning

confidence: 99%

Chemoselective Radical Dehalogenation and C–C Bond Formation on Aryl Halide Substrates Using Organic Photoredox Catalysts

Poelma¹,

Burnett²,

Discekici³

et al. 2016

J. Org. Chem.

114

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Despite the number of methods available for dehalogenation and carbon-carbon bond formation using aryl halides, strategies that provide chemoselectivity for systems bearing multiple carbon-halogen bonds are still needed. Herein, we report the ability to tune the reduction potential of metal-free phenothiazine-based photoredox catalysts and demonstrate the application of these catalysts for chemoselective carbon-halogen bond activation to achieve C-C cross-coupling reactions as well as reductive dehalogenations. This procedure works both for conjugated polyhalides as well as unconjugated substrates. We further illustrate the usefulness of this protocol by intramolecular cyclization of a pyrrole substrate, an advanced building block for a family of natural products known to exhibit biological activity.

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Intermolecular Atom Transfer Radical Addition to Olefins Mediated by Oxidative Quenching of Photoredox Catalysts

Cited by 722 publications

References 66 publications

Evolution of Rhodamine B into Near‐Infrared Dye by Phototriggered Radical Reaction and Its Application for Lysosome‐Specific Live‐Cell Imaging

Evolution of Rhodamine B into Near‐Infrared Dye by Phototriggered Radical Reaction and Its Application for Lysosome‐Specific Live‐Cell Imaging

Olefin difunctionalizations via visible light photocatalysis

Chemoselective Radical Dehalogenation and C–C Bond Formation on Aryl Halide Substrates Using Organic Photoredox Catalysts

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