Blue light-promoted cyclopropenizations of N-tosylhydrazones in water

Yan, Kaichuan; He, Hua; Li, Jianglian; Luo, Yi; Lai, Ruizhi; Guo, Li; Wu, Yong

doi:10.1016/j.cclet.2021.05.031

Cited by 28 publications

(14 citation statements)

References 53 publications

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“…Li et al [97] . introduced a carbene transfer metal‐free reaction of N ‐tosylhydrazones 3 using water with alkynes followed by the formation of diazo intermediate 89 and promoted by the low energy blue light to permit systematic X−H insertion reactions, cyclopropenizations, and cyclopropanation 91 .…”

Section: Heterocyclic Synthesismentioning

confidence: 99%

“…Lu et al [96] describe the one-pot synthesis of polycyclic aromatic compounds 88 via microwave-induced [2 + 2] intramolecular cycloaddition of bis-N-tosylhydrazone 86 and retro-[2 + 2]-cycloaddition of diazetidine 87 without using base and catalyst conditions. The reaction proceeded in an oil bath using various solvents like dimethylacetamide (DMA) and dimethylformamide (DMF) to increase the yield however 1,4-dioxane Li et al [97] introduced a carbene transfer metal-free reaction of N -tosylhydrazones 3 using water with alkynes followed by the formation of diazo intermediate 89 and promoted by the low energy blue light to permit systematic XÀ H insertion reactions, cyclopropenizations, and cyclopropanation 91. When the reaction was occurred in presence of dichloromethane at 25 °C without using the base, no anticipated product was formed.…”

Section: Chemistryselectmentioning

confidence: 99%

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Emerging Trends in N‐Tosylhydrazone Mediated Transition‐Metal‐Free Reactions

et al. 2022

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This review is based on the recent synthetic advancements of N‐tosylhydrazone under metal‐free conditions for the construction of nitrogen‐containing heterocycles. N‐Tosylhydrazones, an emerging building block in current organic chemistry offer moderate and flexible procedures through the carbene intermediates for the formation of C−C and carbon‐heteroatom bonds. N‐Tosylhydrazones are the derivatives of the aldehyde/keto group which act as carbene source, diazo precursors, and alternative of the respective carbonyl group. The key features of the N‐tosylhydrazone chemistry involve selective, controllable, one‐pot synthesis, good functional group tolerance, and metal‐free reactions with a wide scope of substrates. The current study includes mechanistic features, synthetic applications, substrate scope, limitation, and some additional reactions like electrosynthesis, regioselective, chemoselective, annulation, 1,3‐dipolar, and intermolecular cycloaddition.

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Section: Heterocyclic Synthesismentioning

confidence: 99%

Section: Chemistryselectmentioning

confidence: 99%

Emerging Trends in N‐Tosylhydrazone Mediated Transition‐Metal‐Free Reactions

et al. 2022

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“…Recently, visible-light activation of organic compounds has emerged as a new and green paradigm in organic synthesis − and has also been successfully employed to synthesize cyclopropanes. − For instance, the Suero group introduced the photoredox addition of radicals to alkenes followed by intramolecular polar displacement (radical-polar crossover), providing a new entry for the preparation of cyclopropanes . In addition, Molander and co-workers reported another photoredox radical-polar crossover using a newly designed reagent, triethylammonium bis(catecholato)iodomethylsilicate, as a radical precursor.…”

Section: Introductionmentioning

confidence: 99%

“…Compared with the above diazo surrogates, N -tosylhydrazones are readily prepared from carbonyl compounds, which can be ideal and highly desirable carbene precursors to overcome the intrinsic drawback of donor/donor carbenes, such as their instability and high reactivity toward side reactions. − It should be noted that a significant precedent on photochemical carbene transfer reactions of aryl/aryl carbenes was given by the Koenigs group including applications and theoretical background of aryl/aryl carbenes . Nevertheless, the visible-light-mediated activation of N -tosylhydrazones to afford aryl/alkyl carbenes is unknown …”

Section: Introductionmentioning

confidence: 99%

Visible-Light-Mediated Energy Transfer Enables Cyclopropanes Bearing Contiguous All-Carbon Quaternary Centers

Xia

Wang

et al. 2023

ACS Catal.

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Cyclopropanes bearing contiguous all-carbon quaternary centers continue to attract attention due to their bioactivities. However, methods to obtain cyclopropanes with contiguous all-carbon quaternary centers remain largely unexplored due to the high steric hindrance of these compounds. Herein, we report a visible-light-mediated energy-transfer (EnT) strategy to realize in situ donor/donor carbenes from readily available N-tosylhydrazones, facilitating the synthesis of highly congested EWG-free cyclopropanes. Through this approach, cyclopropanes are rapidly installed into complex bioactive molecules, fluorescent molecules, and other useful building blocks that are challenging to synthesize. Detailed mechanistic reactions and DFT studies clearly demonstrated the role of the photosensitizer, the formation of donor/donor carbenes, and the necessity of light and a base in the system.

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“…2 Recently, free carbenes have been generated under mild conditions by deploying visible light irradiation of the corresponding diazo compounds, which allowed a wide range of insertion processes to take place without the aid of a metal catalyst. 4–6 However, the leap toward a mild metal-free catalytic enantioselective insertion of a photo-generated free carbene into an H–X bond has yet to be achieved (Scheme 1c).…”

Section: Introductionmentioning

confidence: 99%