Heterogeneous visible-light promoted dehydrogenative [4 + 2] annulation of benzothioamides and alkynes under aerobic conditions

Guo, Yi; Chang, Rong; Zhang, Fu; Zhou, Cong‐Ying; Guo, Zhen

doi:10.1039/d3gc01329d

Cited by 9 publications

(1 citation statement)

References 71 publications

(17 reference statements)

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“…[38][39][40][41][42] The numerous sulfur(methylthio) groups, on the other hand, were originally meant for functionalization such as facilitating metal uptake and oxidation treatment. As sulfur atoms are associated with many functional radical species in discrete molecules as well as in extended structures, [51][52][53][54] we had wondered if the thermocyclizing the sulfurrich MOF solid of ZrL3 led to radical species. ZrL3 was grown solvothermally in DEF (N,N-diethylformamide) using H2L3, ZrOCl2• 8H2O and CF3COOH as organic linker, metal source and modulator, respectively (Figure 1).…”

Section: Resultsmentioning

confidence: 99%

Insight into Stable, Concentrated Radicals: from Sulfur-functionalized Alkyne-rich Crystalline Frameworks to Simple Alkyne Motifs

Kuang,

Li,

et al. 2024

Preprint

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Organic radicals feature versatile unpaired electrons key for photoelectronic and biomedical applications, but remain difficult to access in stable concentrated forms. We disclose easy generation of stable, concentrated radicals from various alkynyl phenyl motifs, including 1) sulfur-functionalized alkyne-rich organic linkers in crystalline frameworks; 2) the powders of these molecules alone; 3) simple diethynylbenzenes. For Zr-based framework, generation of radical-rich crystalline framework was achieved by thermal annealing in the range of 300‒450 °C. For terminal alkynes, electron paramagnetic resonance signals (EPR; indicative of free radicals) arise after air exposure or mild heating (e.g., 70 °C). Further heating (e.g., 150 °C for 3 hours) raises the radical concentrations up to 3.30 mol kg‒1. For the more stable internal alkynes, transformations into porous radical solids can also be triggered, albeit at higher temperatures (e.g., 250 to 500 °C). The resulted radical-containing solids are porous, stable to air as well as heat (up to 300‒500 °C) and exhibit photothermal conversion capacity. The formation of radicals can be ascribed to extensive alkyne cyclizations, forming defects, dangling bonds and the associated radicals stabilized by the polycyclic π-systems.

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Section: Resultsmentioning

confidence: 99%

Insight into Stable, Concentrated Radicals: from Sulfur-functionalized Alkyne-rich Crystalline Frameworks to Simple Alkyne Motifs

Kuang,

Li,

et al. 2024

Preprint

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Visible Light‐Promoted Mono‐Bromination of Aniline Derivatives and Nitrogen‐Containing Heterocyclic Compounds via Electron Donor‐Acceptor Complex

Sun,

Yang,

Cheng

et al. 2024

Asian J Org Chem

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We present a successful development of a photo‐induced mono‐bromination method for anilines, which eliminates the requirement for photocatalysts and excess bromine sources. Experimental investigations, complemented by computational analyses, establish that this method operates via the formation of an electron donor‐acceptor (EDA) complex. This innovative approach enables the synthesis of highly regioselective mono‐brominated products across a diverse range of substrates, all achieved under mild reaction conditions.

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Photocatalyst‐Free Visible Light‐Induced C(sp²)−H Arylation of Quinoxalin‐2(1H)‐ones and Coumarins

Yu,

Yang,

Chen

et al. 2024

Chemistry A European J

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Herein, we describe a visible light‐induced C(sp2)−H arylation method for quinoxalin‐2(1H)‐ones and coumarins using iodonium ylides without the need for external photocatalysts. The protocol demonstrates a broad substrate scope, enabling the arylation of diverse heterocycles through a simple and mild procedure. Furthermore, the photochemical reaction showcases its applicability in the efficient synthesis of biologically active molecules. Computational investigations at the CASPT2//CASSCF/PCM level of theory revealed that the excited state of quinoxalin‐2(1H)‐one facilitates electron transfer from its π bond to the antibonding orbital of the C−I bond in the iodonium ylide, ultimately leading to the formation of an aryl radical, which subsequently participates in the C‐H arylation process. In addition, our calculations reveal that via single‐ electron transfer (SET) process, the C−I bond cleavage in iodonium ylide and new C−C bond formation between resultant aryl radical and cationic quinoxaline species take place in a concerned manner. This enables the arylation reaction to efficiently proceed along an energy‐efficient route.

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Heterogeneous visible-light promoted dehydrogenative [4 + 2] annulation of benzothioamides and alkynes under aerobic conditions

Abstract: The dehydrogenative [4+2] annulation is a step and atom-economical way to construct benzo-fused six-membered ring which are prevalent in natural products, pharmaceuticals and agrochemicals. Traditional protocols often require C-H activation...

Cited by 9 publications

References 71 publications

Insight into Stable, Concentrated Radicals: from Sulfur-functionalized Alkyne-rich Crystalline Frameworks to Simple Alkyne Motifs

Insight into Stable, Concentrated Radicals: from Sulfur-functionalized Alkyne-rich Crystalline Frameworks to Simple Alkyne Motifs

Visible Light‐Promoted Mono‐Bromination of Aniline Derivatives and Nitrogen‐Containing Heterocyclic Compounds via Electron Donor‐Acceptor Complex

Photocatalyst‐Free Visible Light‐Induced C(sp²)−H Arylation of Quinoxalin‐2(1H)‐ones and Coumarins

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Heterogeneous visible-light promoted dehydrogenative [4 + 2] annulation of benzothioamides and alkynes under aerobic conditions

Abstract: The dehydrogenative [4+2] annulation is a step and atom-economical way to construct benzo-fused six-membered ring which are prevalent in natural products, pharmaceuticals and agrochemicals. Traditional protocols often require C-H activation...

Cited by 9 publications

References 71 publications

Insight into Stable, Concentrated Radicals: from Sulfur-functionalized Alkyne-rich Crystalline Frameworks to Simple Alkyne Motifs

Insight into Stable, Concentrated Radicals: from Sulfur-functionalized Alkyne-rich Crystalline Frameworks to Simple Alkyne Motifs

Visible Light‐Promoted Mono‐Bromination of Aniline Derivatives and Nitrogen‐Containing Heterocyclic Compounds via Electron Donor‐Acceptor Complex

Photocatalyst‐Free Visible Light‐Induced C(sp2)−H Arylation of Quinoxalin‐2(1H)‐ones and Coumarins

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Photocatalyst‐Free Visible Light‐Induced C(sp²)−H Arylation of Quinoxalin‐2(1H)‐ones and Coumarins