Photoinduced inverse Sonogashira coupling reaction

Zhang, Lizhu; Wei, Cunbo; Wu, Jiayue; Liú, Dan; Yao, Yinchao; Chen, Zhuo; Liu, Jianxun; Yao, Chang‐Jiang; Li, Dinghua; Yang, Rongjie; Xia, Zhonghua

doi:10.1039/d2sc01933g

Cited by 19 publications

(7 citation statements)

References 74 publications

(33 reference statements)

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“…In contrast, the triplet energy is determined by density functional theory calculation [UCAM-B3LYP/6-311 + G(d,p)] for 2a (66.9 kcal/mol) to be lower than that of the photocatalyst 4CzIPN (69.0 kcal/mol), indicating that the reaction is initiated by photoinduced triplet-to-triplet energy transfer (TTEnT) between the excited photocatalyst 4CzIPN* and 2a to form 2a * and is feasible (Scheme d). Next, the excited 2a * homolytic cleavage generates a radical pair of I and II . II then proceeds to cleavage to give a trifluoromethyl radical III and release SO 2 .…”

Section: Resultsmentioning

confidence: 99%

Visible-Light-Initiated Sequential Trifluoromethylation/Remote C(sp³)–H Alkynylation of Vinyl Azides by Radical Relay

et al. 2023

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A visible-light-initiated trifluoromethylation/remote aliphatic C–H alkynylation of α-alkyl-substituted vinyl azides using acetylenic triflones as both the trifluoromethyl and alkyne donors is described. The reaction occurred under environmentally benign and radical initiator-free reaction conditions, affording γ-alkynylated trifluoromethyl ketone derivatives with a broad scope of substituents. Mechanistic studies suggested that the reaction is initiated via a triplet–triplet energy transfer between the 4CzIPN catalyst and acetylenic triflone, followed by fragmentation to generate a trifluoromethyl radical and an alkynyl radical.

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Section: Resultsmentioning

confidence: 99%

Visible-Light-Initiated Sequential Trifluoromethylation/Remote C(sp³)–H Alkynylation of Vinyl Azides by Radical Relay

et al. 2023

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“…In spite of this, only one photoinduced inverse Sonogashira reaction work has been mentioned. In that context, Zhonghua Xia et al 49 in 2022, unveiled a photocatalyst-free and transition metal-free inverse Sonogashira reaction under visible light between iodoalkyne and arenes (Scheme 21). The direct photoexcitation of iodo alkynes for the inverse Sonogashira coupling reaction showcased a broad substrate scope.…”

Section: Photoinduced Inverse Sonogashira Coupling Reactionmentioning

confidence: 99%

Photochemical Sonogashira coupling reactions: beyond traditional palladium–copper catalysis

Singh,

Shaikh

2023

Chem. Commun.

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“…Noteworthy, the present protocol allows the C−H alkynylation under a silver‐free conditions which is otherwise a prime requirement for a similar thermally induced transformation [15] . In a very recent report, a non‐directed strategy for photo‐induced inverse Sonogashira reaction is reported with alkynyl iodides [16] . However, the transformation is found to be specific to electronically rich arenes and heteroarenes.…”

Section: Introductionmentioning

confidence: 99%

Substrate‐Rhodium Cooperativity in Photoinducedortho‐Alkynylation of Arenes

et al. 2022

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In the realm of metallaphotocatalytic C-H activation strategy, the mode of reaction which has been mostly explored is the synergistic effect between a photocatalyst (PC) and a transition metal. In these cases, the energy and redox transfer from the PC to transition metal modulates the oxidation state which brings new mechanistic paradigms in C-H activation and enables prior elusive transformations under milder conditions. Another mode of reactivity occurs via the direct excitation of the transition metal which plays the dual role of light energy harnessing alongside performing the bond breaking and forming. This mode is advantageous because it would not require any exogenous PC, however such reactivity by transition metals is rare in literature. In this context we have developed the rst photo-induced Rh-catalyzed orthoalkynylation under ambient conditions without the requirement of silver salt, PC or any engineered substrate or catalyst. The transformation functions by the speci c cooperative effect of a six-membered rhodacycle which is the photo-responsive species. The catalytic system allows the conjugation of arenes with sp3-rich pharmacophoric fragments. The control experiments as well as the computational studies resolve the mechanistic intricacies for this transformation. An outer sphere electron transfer process from Rh to alkynyl radical is operative for the present photo-induced transformation over the more common oxidative addition or 1,2-migratory insertion pathways. Main TextThe C-H activation strategy gives the provision to streamline the overall process toward a target molecule; thereby empowering the genre of organic synthesis. 1 However, it is a general convention that for a thermally induced C-H activation, a transition metal catalyst is usually accompanied with stoichiometric silver or copper oxidants. 2 This questions the practicality of the method. In order to harness the applicability in true terms it is required to utilize an alternative energy resource that would provide the same outcome but in a sustainable manner. 3 This is where the merger of transition metal catalysis and photocatalysis ts in aptly. The metallaphotocatalysis is an expanding domain in organic synthesis that has revisited and recreated the traditional modes of transition metal catalyzed reactions via unorthodox open-shell mechanisms. 4 The metallaphotocatalysis functions by leveraging on the modulated oxidation state of metal complex involved or generating excited form of intermediate catalytic species; which accounts for the key organometallic step of the transformation. 5 Thus, metallaphotocatalysis provides access to unique reactivity modes through entirely new mechanistic paradigms, that complements the conventional mechanistic approach in the realm of transition metal catalysis. The rede ned mechanistic features enabled by metallaphotocatalysis allow the accomplishment of prior elusive transformations.In general, the metallaphotocatalysis operates by two distinct modes. The rst mode constitutes of the synergistic coo...

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Photoinduced inverse Sonogashira coupling reaction

Abstract: Alkynes are widely used in chemistry, medicine and materials science. Here we demonstrate a transition-metal and photocatalyst-free inverse Sonogashira coupling reaction between iodoalkynes and (hetero)arenes or alkenes under visible-light irradiation....

Cited by 19 publications

References 74 publications

Visible-Light-Initiated Sequential Trifluoromethylation/Remote C(sp³)–H Alkynylation of Vinyl Azides by Radical Relay

Visible-Light-Initiated Sequential Trifluoromethylation/Remote C(sp³)–H Alkynylation of Vinyl Azides by Radical Relay

Photochemical Sonogashira coupling reactions: beyond traditional palladium–copper catalysis

Substrate‐Rhodium Cooperativity in Photoinducedortho‐Alkynylation of Arenes

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Photoinduced inverse Sonogashira coupling reaction

Abstract: Alkynes are widely used in chemistry, medicine and materials science. Here we demonstrate a transition-metal and photocatalyst-free inverse Sonogashira coupling reaction between iodoalkynes and (hetero)arenes or alkenes under visible-light irradiation....

Cited by 19 publications

References 74 publications

Visible-Light-Initiated Sequential Trifluoromethylation/Remote C(sp3)–H Alkynylation of Vinyl Azides by Radical Relay

Visible-Light-Initiated Sequential Trifluoromethylation/Remote C(sp3)–H Alkynylation of Vinyl Azides by Radical Relay

Photochemical Sonogashira coupling reactions: beyond traditional palladium–copper catalysis

Substrate‐Rhodium Cooperativity in Photoinducedortho‐Alkynylation of Arenes

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Product

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Visible-Light-Initiated Sequential Trifluoromethylation/Remote C(sp³)–H Alkynylation of Vinyl Azides by Radical Relay

Visible-Light-Initiated Sequential Trifluoromethylation/Remote C(sp³)–H Alkynylation of Vinyl Azides by Radical Relay