Palladium-Catalyzed Carbene Coupling Reactions of Cyclobutanone <i>N</i>-Sulfonylhydrazones

Ning, Xiaoqin; Chen, Yongke; Hu, Fangdong; Xia, Ying

doi:10.1021/acs.orglett.1c03052

Cited by 16 publications

(13 citation statements)

References 40 publications

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“…High-resolution mass spectral analysis (HRMS) data were measured on a Bruker Apex II. Substrates 1a – 1n and 2a – 2i were synthesized as per the previous literature.…”

Section: Experimental Sectionmentioning

confidence: 99%

“…On the other hand, N -tosylhydrazones were exploited as good coupling partners in palladium-catalyzed carbene coupling reactions and made an important breakthrough; , four-membered ring ketone-derived N -tosylhydrazones with strained were less explored until now. Only one example is the palladium-catalyzed coupling of cyclobutanone-derived N -tosylhydrazones with aryl or benzyl halides, which was discovered by Xia and co-workers . Therefore, developing more new types of reactions for the application of cyclobutanone N -tosylhydrazones is continuously in demand.…”

Section: Introductionmentioning

confidence: 99%

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Palladium-Catalyzed Cyclization Coupling with Cyclobutanone-Derived N-Tosylhydrazones: Synthesis of Benzofuran-3-Cyclobutylidenes and Spirocyclobutanes

et al. 2023

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A palladium-catalyzed cyclization coupling of iodoarene-tethered alkynes with cyclobutanone-derived N-tosylhydrazones is reported, providing a convenient and efficient approach to benzofuran-3-cyclobutylidenes. On this basis, spirocyclobutanes can be generated smoothly in an efficient cascade manner by the addition of dienophiles. Good yields and scalability are demonstrated. Sequential intramolecular carbopalladation, palladium–carbene migratory insertion, δ-hydride elimination, and cycloaddition processes are involved.

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“…High-resolution mass spectral analysis (HRMS) data were measured on a Bruker Apex II. Substrates 1a – 1n and 2a – 2i were synthesized as per the previous literature.…”

Section: Experimental Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Palladium-Catalyzed Cyclization Coupling with Cyclobutanone-Derived N-Tosylhydrazones: Synthesis of Benzofuran-3-Cyclobutylidenes and Spirocyclobutanes

et al. 2023

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“…For instance, Xia and colleagues recently reported an elegant palladium-catalyzed cross-coupling reaction of benzyl chloride with strained cyclobutanone-derived Nsulfonylhydrazones, in which they found that N-triftosylhydrazone resulted in a much higher yield than N-tosylhydrazone (e.g., compound 70a, 84% vs 29% yield, respectively) (Scheme 15). 51 In addition, the reaction could be carried out in a one-pot procedure without the isolation and purification of Ntriftosylhydrazones. preparing, and investigating new types of functionalized Ntriftosylhydrazones; and (iii) applying these methods as key steps to improve the synthesis efficiency of drugs and natural products.…”

Section: Cross-coupling Of Benzyl Chlorides Withmentioning

confidence: 99%

N-Triftosylhydrazones: A New Chapter for Diazo-Based Carbene Chemistry

et al. 2022

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Conspectus Over recent decades, N-sulfonylhydrazones have attracted significant attention in academic and industrial contexts owing to their ease of preparation, versatile reactivity, high stability, and practicality. In particular, the use of N-sulfonylhydrazones as precursors for diazo compounds has paved the way for innovative and original organic reactions that are otherwise difficult to achieve. Three key developments are noteworthy in the history of N-sulfonylhydrazone chemistry: (1) Bamford and Stevens initially disclosed the application of N-tosylhydrazones as a diazo source in 1952; (2) Aggarwal and co-workers investigated N-tosylhydrazone salts as diazo precursors for sulfur ylide-mediated asymmetric epoxidation and aziridination in 2001; and (3) Barluenga, Valdés and co-workers first reported Pd-catalyzed cross-coupling reactions with N-tosylhydrazones in 2007, thus introducing the direct use of N-tosylhydrazones in carbene transfer reactions. In the past 2 decades, the synthetic exploration of N-sulfonylhydrazones in carbene chemistry has increased remarkably. N-Tosylhydrazones are the most commonly used N-sulfonylhydrazones, but they are not easy to decompose and normally need relatively high temperatures (e.g., 90–110 °C). Temperature, as a key reaction parameter, has a significant influence on the selectivity and scope of organic reactions, especially the enantioselectivity. Aggarwal and co-workers have addressed this issue by using N-tosylhydrazone salts and achieved a limited number of asymmetric organic reactions, but the method is greatly limited because the salts must be freshly prepared or stored in the dark at −20 °C prior to use. Hence, easily decomposable N-sulfonylhydrazones, especially those capable of decomposing at low temperature, should open up new opportunities for the development of N-sulfonylhydrazone chemistry. Since 2014, our group has worked toward this goal and eventually identified N-2-(trifluoromethyl)benzenesulfonylhydrazone (i.e., N-triftosylhydrazone) as an efficient diazo surrogate that can decompose at temperatures as low as −40 °C. This allowed us to carry out a range of challenging synthetic transformations and to broaden the applications of some known reactions of great relevance. In this Account, we report our achievements in the application of N-triftosylhydrazones in carbene chemistry. On the basis of the reaction types, such applications can be categorized as (i) C(sp3)–H insertion reactions, (ii) defluorinative reactions of fluoroalkyl N-triftosylhydrazones, (iii) cycloaddition reactions with alkenes and alkynes, and (iv) asymmetric reactions. Additional applications in Doyle–Kirmse rearrangements and cross-coupling with isocyanides (ours) and benzyl chlorides (from the group of Xia) are also summarized in this Account concerning miscellaneous reactions. In terms of reaction efficiency, selectivity, and functional group tolerance, N-triftosylhydrazones are generally superior to traditional N-tosylhydrazones because of their easy decomposition. Mechanistic inv...

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“…6 In 2021, our group reported the synthesis of cyclobutenes and methylenecyclobutanes through palladium-catalyzed carbene coupling reactions of cyclobutanone-derived N-sulfonylhydrazones with organohalides. 7 On the basis of this study, we speculated that the strained cyclic π-allylpalladium intermediate could be generated from cyclobutenone-derived Ntosylhydrazones and organohalides via a carbene strategy, 8 thus providing an alternative avenue for the investigation of this intriguing intermediate. Herein, we carry out considerable exploration of this reaction and present our findings in this direction.…”

mentioning

confidence: 96%

“…On the contrary, transition metal-catalyzed carbene coupling reactions have attracted considerable attention in recent years . In 2021, our group reported the synthesis of cyclobutenes and methylenecyclobutanes through palladium-catalyzed carbene coupling reactions of cyclobutanone-derived N -sulfonylhydrazones with organohalides . On the basis of this study, we speculated that the strained cyclic π-allylpalladium intermediate could be generated from cyclobutenone-derived N -tosylhydrazones and organohalides via a carbene strategy, thus providing an alternative avenue for the investigation of this intriguing intermediate.…”

mentioning

confidence: 99%

Cross-Coupling of Cyclobutenone N-Tosylhydrazones with Organohalides: Access to Conjugated Enynes and Enallenes via a Strained Allylpalladium Intermediate

Ning

Chen

et al. 2022

Org. Lett.

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A palladium-catalyzed cross-coupling reaction of cyclobutenone N-tosylhadrazones with organohalides is disclosed. The protocol involves the generation of a strained allylpalladium intermediate from readily available starting materials through palladium carbene migratory insertion, which undergoes electrocyclic ring opening and β-hydride elimination for the production of conjugated enynes and enallenes. The broad substrate scope, good to excellent yields, and tunable product diversity make the protocol potentially useful in organic synthesis.

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Palladium-Catalyzed Carbene Coupling Reactions of Cyclobutanone N-Sulfonylhydrazones

Cited by 16 publications

References 40 publications

Palladium-Catalyzed Cyclization Coupling with Cyclobutanone-Derived N-Tosylhydrazones: Synthesis of Benzofuran-3-Cyclobutylidenes and Spirocyclobutanes

Palladium-Catalyzed Cyclization Coupling with Cyclobutanone-Derived N-Tosylhydrazones: Synthesis of Benzofuran-3-Cyclobutylidenes and Spirocyclobutanes

N-Triftosylhydrazones: A New Chapter for Diazo-Based Carbene Chemistry

Cross-Coupling of Cyclobutenone N-Tosylhydrazones with Organohalides: Access to Conjugated Enynes and Enallenes via a Strained Allylpalladium Intermediate

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