Three‐Component Reaction for the Synthesis of Highly Functionalized Propargyl Ethers

Pisella, Guillaume; Gagnebin, Alec; Waser, Jérôme

doi:10.1002/chem.202001317

Cited by 22 publications

(17 citation statements)

References 78 publications

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“…Generally, transition metal-catalyzed carbene insertion into the O–H bond of water represents an efficient and atom-economical approach for the synthesis of secondary alcohols (Scheme A) . Stimulated by the unprecedented performance of fluoroalkyl N -triftosylhydrazones in carbodefluorination reactions, we wondered whether the use of water enables selective O–H insertion or triggers hydrodefluorination to afford partially fluorinated compounds.…”

Section: Defluorinative Functionalization Of Fluoroalkyl N-triftosylh...mentioning

confidence: 99%

“…The asymmetric transformation based on diazo-derived carbene intermediates is one of the most popular methods for the construction of chiral organic molecules. ,,, Nevertheless, the direct use of N -sulfonylhydrazones in asymmetric synthesis remains a long-standing issue, mainly due to their relatively high decomposition temperature. To date, the few examples using N -tosylhydrazones or their salts have all been performed above 0 °C (Scheme A). , The demand for N -sulfonylhydrazones capable of decomposing at relatively low temperatures, such as below 0 °C, to expand their use in asymmetric reactions continues unabated.…”

Section: Asymmetric Reactionsmentioning

confidence: 99%

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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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Section: Defluorinative Functionalization Of Fluoroalkyl N-triftosylh...mentioning

confidence: 99%

Section: Asymmetric Reactionsmentioning

confidence: 99%

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

et al. 2022

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“…381 While initially only used for the synthesis of esters derived from the EBX reagent, this methodology was subsequently extended to enable the synthesis of a broad range of ethers (including α-tertiary ethers) by variation of the nucleophilic alcohol component in the reaction. 382 Waser has also employed analogous vinylbenziodoxolone (VBX) reagents to enable oxyvinylation of diazo compounds and demonstrated the applicability to the synthesis of α-tertiary ethers. 383 The proposed mechanisms for the oxyfunctionalisation of diazo compounds are comparable: 384 the diazo compound is thought to form metal carbenoid I which is intercepted by the alcohol component to form an onium ylide II .…”

Section: Miscellaneousmentioning

confidence: 99%

Branching out: redox strategies towards the synthesis of acyclic α-tertiary ethers

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“…In 2020, we disclosed the insertion of VBX reagents into diazo compounds using copper catalysis ( Scheme 14). [58] Based on our previous experience on oxyalkynylation, [76–78] we identified VBX reagents 2 as privileged partners to realize the 1,1‐oxyvinylation of transient copper‐carbene intermediates. This transformation cannot be performed using existing methodologies with vinyl halides [79–81] .…”

Section: Vbxmentioning

confidence: 99%

Vinylbenziodoxol(on)es: Synthetic Methods and Applications

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Pisella

Waser

2020

Helvetica Chimica Acta

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Cyclic hypervalent iodine reagents are now frequently used in synthetic organic chemistry, either as oxidants or group-transfer reagents. Vinylbenziodoxol(on)es (VBXs) bearing alkene substituents have been less investigated than the corresponding trifluoromethyl or alkynyl reagents. Nevertheless, since 2016 the development of new synthetic methods to access VBXs has awakened the interest of the synthetic community, leading to new transformations highlighting their unique reactivity as electrophilic alkene synthons. In this review, an overview of the synthesis and applications of VBX reagents will be presented. The review is organized according to the two main classes of VBX reagents reported so far-simple alkyl/aryl-substituted VBXs and heteroatom (S, O, N, X)-substituted VBXs-as they differ significantly from the point of view of synthetic access.

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Three‐Component Reaction for the Synthesis of Highly Functionalized Propargyl Ethers

Cited by 22 publications

References 78 publications

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

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

Branching out: redox strategies towards the synthesis of acyclic α-tertiary ethers

Vinylbenziodoxol(on)es: Synthetic Methods and Applications

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