Palladium-Catalyzed Condensation of <i>N</i>-Aryl Imines and Alkynylbenziodoxolones To Form Multisubstituted Furans

Lu, Beili; Wu, Junliang; Yoshikai, Naohiko

doi:10.1021/ja5059795

Cited by 120 publications

(63 citation statements)

References 46 publications

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“…A new type of palladium-catalyzed transformation involving EBX reagents was reported by Yoshikai and co-workers. [85] When EBX reagents were reacted with ketimines, furans incorporating the iodoaryl group of the reagent were obtained (Scheme 41, A).…”

Section: Other Transformationsmentioning

confidence: 99%

Cyclic Hypervalent Iodine Reagents for Atom‐Transfer Reactions: Beyond Trifluoromethylation

et al. 2016

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Hypervalent iodine compounds are privileged reagents in organic synthesis because of their exceptional reactivity. Among these compounds, cyclic derivatives stand apart because of their enhanced stability. They have been widely used as oxidants, but their potential for functional‐group transfer has only begun to be investigated recently. The use of benziodoxol(on)es for trifluoromethylation (Togni's reagents) is already widely recognized, but other transformations have also attracted strong interest recently. In this Review, the development in the area since 2011 will be presented. After a short summary of synthetic methods to prepare benziodoxol(on)e reagents, their use to construct carbon–heteroatom and carbon–carbon bonds will be presented. In particular, the introduction of alkynes by using ethynylbenziodoxol(on)e (EBX) reagents has been highly successful. Breakthroughs in the introduction of alkoxy, azido, difluoromethyl, and cyano groups will also be described.

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Section: Other Transformationsmentioning

confidence: 99%

Cyclic Hypervalent Iodine Reagents for Atom‐Transfer Reactions: Beyond Trifluoromethylation

et al. 2016

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“…With EBX reagents, progress in this area has been limited to a report of Yoshikai and coworkers on the palladium-catalyzed reaction of imines with alkynylbenziodoxolones to give furan derivatives. 10 …”

mentioning

confidence: 99%

Copper-Catalyzed Oxy-Alkynylation of Diazo Compounds with Hypervalent Iodine Reagents

2016

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Alkynes have found widespread applications in synthetic chemistry, biology and materials sciences. In recent years, methods based on electrophilic alkynylation with hypervalent iodine reagents have made acetylene synthesis more flexible and efficient, but they lead to the formation of one equivalent of an iodoarene as side-product. Herein, a more efficient strategy involving a copper-catalyzed oxy-alkynylation of diazo compounds with ethynylbenziodoxol(on)e (EBX) reagents is described, which proceeds with generation of nitrogen gas as the only waste. This reaction is remarkable for its broad scope in both EBX reagents and diazo compounds. In addition, vinyl diazo compounds gave enynes selectively as single geometric isomers. The functional groups introduced during the transformation served as easy handles to access useful building blocks for synthetic and medicinal chemistry.The carbon-carbon triple bond is among the most valuable functional groups in organic chemistry because of its versatile reactivity. 1 Alkynes are broadly applied as chemical building blocks for the synthesis of fine chemicals. 2 In past years, they have also gained a lot of interest for applications in biochemistry or material sciences. 1,3 As a result of this growing importance of alkynes, developing more efficient and versatile methods for their synthesis is of fundamental importance. Alkynes are often accessed by the addition of acetylides on electrophilic positions of molecules. 4 However, introducing triple bonds only to electrophilic positions strongly limits the flexibility and efficiency of alkyne synthesis. Major efforts have therefore been made to develop electrophilic alkynylation methods, relying on the umpolung of the innate reactivity of acetylenes (Scheme 1A). 5 Hypervalent iodine reagents such as alkynyliodonium salts have been particularly successful for the electrophilic alkynylation of nucleophiles. 6 However, the use of alkynyliodonium salts is limited due to their low stability. Recently, EthynylBenziodoXol(on)es (EBX) 7a,b have been introduced as excellent electrophilic reagents for the alkynylation of ketoesters, 7c thiols, 7d and aromatic C-H bonds using transition metal catalysis, 7e-g among many other successful transformations. 7h Nevertheless, the developed methods are often restricted to the transfer of one type of acetylenes (either silyl-, aryl-or alkyl-substituted). Furthermore, 2-iodobenzoic acid is usually obtained as a stoichiometric byproduct after alkynylation, resulting in low atom economy. 8 Recently, Greaney and co-workers 9a and Dauban and co-workers 9b reported more atom economical transformations based on the use of the formed aryl iodides in cross-coupling reactions with aryliodonium salts and PhI(OPiv)2, respectively. With EBX reagents, progress in this area has been limited to a report of Yoshikai and coworkers on the palladium-catalyzed reaction of imines with alkynylbenziodoxolones to give furan derivatives. 10 Scheme 1. Alkynylation strategies and multi-component reactions usin...

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“…Product 3a was formed in 47% yield at lower temperature (75°C ) using DCE as solvent. It is notable that application of nonpolar solvents such as benzene and polar solvents such as MeCN and i-PrOH were not productive (entries 5, 8,9). Therefore, we selected DCE as the solvent of choice for the annulation of arylmethyl ketone and acetylenedicarboxylate.…”

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confidence: 99%

Copper(I)-Catalyzed Radical Addition of Acetophenones to Alkynes in Furan Synthesis

Manna

Antonchick

2015

Org. Lett.

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A synthesis of multisubstituted furans from readily available acetophenones and electron-deficient alkynes via direct C(sp(3))-H bond functionalization under radical reaction conditions is described. The developed transformation is catalyzed by copper(I) salts using di-tert-butyl peroxide as an external oxidant. This method offers an efficient access to biologically important scaffolds from simple compounds.

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Palladium-Catalyzed Condensation of N-Aryl Imines and Alkynylbenziodoxolones To Form Multisubstituted Furans

Cited by 120 publications

References 46 publications

Cyclic Hypervalent Iodine Reagents for Atom‐Transfer Reactions: Beyond Trifluoromethylation

Cyclic Hypervalent Iodine Reagents for Atom‐Transfer Reactions: Beyond Trifluoromethylation

Copper-Catalyzed Oxy-Alkynylation of Diazo Compounds with Hypervalent Iodine Reagents

Copper(I)-Catalyzed Radical Addition of Acetophenones to Alkynes in Furan Synthesis

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