Nickel-Catalyzed Photodehalogenation of Aryl Bromides

Higginson, Bradley; Sanjosé‐Orduna, Jesús; Gu, Yiting; Martı́n, Rubén

doi:10.1055/s-0040-1720893

Cited by 3 publications

(7 citation statements)

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“…The aryl radical can subsequently abstract a deuterium atom from deuterated isopropanol, and the so-formed isopropyl radical reduces Pd(I), thus closing the catalytic cycle. A similar concept was used for a light-mediated nickel-catalyzed protodehalogenation reaction in which THF served as the proton source (Scheme b) . Switching to deuterated THF, the applicability of this methodology for deuteration was demonstrated on three substrates, showing high deuterium incorporation and moderate yields.…”

Section: Reductive Deuterationmentioning

confidence: 99%

“…A similar concept was used for a light-mediated nickelcatalyzed protodehalogenation reaction in which THF served as the proton source (Scheme 65b). 222 Switching to deuterated THF, the applicability of this methodology for deuteration was demonstrated on three substrates, showing high deuterium incorporation and moderate yields.…”

Section: Deuteration Of Aldehydes By Hiementioning

confidence: 99%

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Recent Developments for the Deuterium and Tritium Labeling of Organic Molecules

et al. 2022

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Organic compounds labeled with hydrogen isotopes play a crucial role in numerous areas, from materials science to medicinal chemistry. Indeed, while the replacement of hydrogen by deuterium gives rise to improved absorption, distribution, metabolism, and excretion (ADME) properties in drugs and enables the preparation of internal standards for analytical mass spectrometry, the use of tritium-labeled compounds is a key technique all along drug discovery and development in the pharmaceutical industry. For these reasons, the interest in new methodologies for the isotopic enrichment of organic molecules and the extent of their applications are equally rising. In this regard, this Review intends to comprehensively discuss the new developments in this area over the last years (2017−2021). Notably, besides the fundamental hydrogen isotope exchange (HIE) reactions and the use of isotopically labeled analogues of common organic reagents, a plethora of reductive and dehalogenative deuteration techniques and other transformations with isotope incorporation are emerging and are now part of the labeling toolkit.

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Section: Reductive Deuterationmentioning

confidence: 99%

Section: Deuteration Of Aldehydes By Hiementioning

confidence: 99%

Recent Developments for the Deuterium and Tritium Labeling of Organic Molecules

et al. 2022

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“…Higher concentrations and reaction times (entries 7–9 in Tabe 1) lead to larger extents of conversion (up to 61% at 18 h) and favor formation of bibenzyl over toluene (up to 52% yield at 18 h). [BnBr] •– presumably cleaves to afford Bn • , which can react further to form Bn 2 (see following section) or can form toluene through reaction with THF, which is known to have a reasonably weak α-CH bond and act as a H • donor towards many radicals [ 28 – 31 ].…”

Section: Resultsmentioning

confidence: 99%

“…This may be attributable to the lower stability and greater reactivity of aryl radicals relative to that of their benzyl counterparts. Indeed, aryl radicals are known to abstract H • from THF [ 30 – 31 ] and presumably do so in the present reactions before any further reactions can occur. Resonance-stabilized benzyl radicals, on the other hand, are sufficiently long-lived to react further to afford dimeric bibenzyl derivatives (especially at higher concentrations or when photoirradiation is used, presumably affording higher steady-state [R • ] concentrations).…”

Section: Resultsmentioning

confidence: 99%

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

Tang,

Brown,

Risko

et al. 2023

Beilstein J. Org. Chem.

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2,2’-Bis(4-dimethylaminophenyl)- and 2,2'-dicyclohexyl-1,1',3,3'-tetramethyl-2,2',3,3'-tetrahydro-2,2'-bibenzo[d]imidazole ((N-DMBI)2 and (Cyc-DMBI)2) are quite strong reductants with effective potentials of ca. −2 V vs ferrocenium/ferrocene, yet are relatively stable to air due to the coupling of redox and bond-breaking processes. Here, we examine their use in accomplishing electron transfer-induced bond-cleavage reactions, specifically dehalogenations. The dimers reduce halides that have reduction potentials less cathodic than ca. −2 V vs ferrocenium/ferrocene, especially under UV photoexcitation (using a 365 nm LED). In the case of benzyl halides, the products are bibenzyl derivatives, whereas aryl halides are reduced to the corresponding arenes. The potentials of the halides that can be reduced in this way, quantum-chemical calculations, and steady-state and transient absorption spectroscopy suggest that UV irradiation accelerates the reactions via cleavage of the dimers to the corresponding radical monomers.

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“…The successful preparation of substrates bearing particularly weak benzylic sp 3 C–H bonds ( 2b , 2e , 2j , 2k , 2o , 2p , 2r , 2s , and 2u ) is certainly noteworthy, as these motifs might a priori be susceptible to HAT processes from I (Scheme ) because of the significant spin density on the oxygen atom of its (n,π*) triplet excited state. Equally interesting is the site-selectivity shown for 2l ; under the limits of detection, no photoreduction of the sp 2 C–Br was observed in the crude mixtures, indicating that our protocol might complement existing metal-catalyzed reduction events that would otherwise result in the cleavage of the latter . Encouraged by these results, we wondered whether our defunctionalization protocol could be extended beyond sp 3 C–Br linkages, specifically to abundant, yet naturally occurring, native sp 3 C–N, C–O, and C–C bond linkages .…”

mentioning

confidence: 93%

Defunctionalization of sp³ C–Heteroatom and sp³ C–C Bonds Enabled by Photoexcited Triplet Ketone Catalysts

Yin

Wakeling

et al. 2022

ACS Catal.

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A general strategy for enabling a light-induced defunctionalization of sp 3 C−heteroatom and sp 3 C−C bonds with triplet ketone catalysts and bipyridine additives is disclosed. This protocol is characterized by its broad scope without recourse to transition metal catalysts or stoichiometric exogeneous reductants, thus offering a complementary technique for activating σ sp 3 C− C(heteroatom) bonds. Preliminary mechanistic studies suggest that the presence of 2,2′-bipyridines improves the lifetime of ketyl radical intermediates.

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Nickel-Catalyzed Photodehalogenation of Aryl Bromides

Cited by 3 publications

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Recent Developments for the Deuterium and Tritium Labeling of Organic Molecules

Recent Developments for the Deuterium and Tritium Labeling of Organic Molecules

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

Defunctionalization of sp³ C–Heteroatom and sp³ C–C Bonds Enabled by Photoexcited Triplet Ketone Catalysts

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Nickel-Catalyzed Photodehalogenation of Aryl Bromides

Cited by 3 publications

References 0 publications

Recent Developments for the Deuterium and Tritium Labeling of Organic Molecules

Recent Developments for the Deuterium and Tritium Labeling of Organic Molecules

Beyond n-dopants for organic semiconductors: use of bibenzo[d]imidazoles in UV-promoted dehalogenation reactions of organic halides

Defunctionalization of sp3 C–Heteroatom and sp3 C–C Bonds Enabled by Photoexcited Triplet Ketone Catalysts

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Defunctionalization of sp³ C–Heteroatom and sp³ C–C Bonds Enabled by Photoexcited Triplet Ketone Catalysts