Palladium‐Catalyzed Cross‐Coupling of Internal Alkenes with Terminal Alkenes to Functionalized 1,3‐Butadienes Using CH Bond Activation: Efficient Synthesis of Bicyclic Pyridones

Yu, Haifeng; Jin, Weiwei; Sun, Cheng; Chen, Jiping; Du, Wangmin; He, Shan; Yu, Zhengkun

doi:10.1002/ange.201002737

Cited by 52 publications

(17 citation statements)

References 46 publications

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“…In comparison, the reaction was more complex for 1 n , which does not have a substituent at the α‐position (R 1 =H), and thus afforded the desired product 3 n in only 27 % yield (entry 14) along with 3 h in 20 % yield. In this case, the formation of 3 h may result from the first α‐phenylation of 1 n with benzyne by a palladium‐catalyzed α‐CH activation6d to give 1 h , and subsequent annulation with benzyne (for details, see the Supporting Information). In addition, the ketene dithioacetals 1 o – q , having an ethylthio functional group, also proved to be suitable substrates for this process (entries 15–17).…”

Section: Methodsmentioning

confidence: 99%

Palladium‐Catalyzed CS Activation/Aryne Insertion/Coupling Sequence: Synthesis of Functionalized 2‐Quinolinones

et al. 2014

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Abstract:The insertion of an aryne into a C À S bond can suppress the addition of an S nucleophile to the aryne in the presence of palladium. Catalyzed by Pd(OAc) 2 , a wide range of a-carbamoyl ketene dithioacetals readily react with arynes to selectively afford functionalized 2-quinolinones in high yields under neutral reaction conditions by a C À S activation/ aryne insertion/intramolecular coupling sequence. The attractive feature of the new strategy also lies in the versatile transformations of the alkythio-substituted quinolinone products. Transition-metal-catalyzedCÀSbondactivationforCÀCandC-heteroatom bond formation has fascinated organic chemists for decades.[1] A variety of organosulfur compounds have been utilized and have great potential in these processes [1][2][3] because of their ready availability, stability, and structural diversity, as compared to the corresponding organic halide coupling partners.[4] Cross-coupling chemistry with thioorganics along with new reaction patterns, exceptional selectivity, or unique reactivity would be highly desirable.Inspired by palladium-catalyzed desulfitative coupling of thioesters, [1c, 2a-d] we recently became interested in transitionmetal-catalyzed CÀS bond cleavage for CÀC bond formation during our research [5] on ketene dithioacetals, which are easily prepared and widely applied as organic intermediates.[6] We have already achieved copper-catalyzed desulfitative C À C cross-coupling of a-oxo ketene dithioacetals with arylboronic acids, [3a] and then palladium-catalyzed/copper-mediated desulfitative annulation of 2-methylthiobenzofurans with 2-hydroxyphenylboronic acids.[3b] More recently, a CÀS bond activation protocol for Heck-type cyclization of a-alkenoyl ketene dithioacetals was also developed in our group.[3c] To take advantage of the synthetic power of functionalized ketene dithioacetals [3,5,6] and the tremendous applications of arynes in cyclization reactions, [7] we envisioned the palladiumcatalyzed CÀS activation as the key to developing an annulation between arynes and a-carbamoyl ketene dithioacetals (1; Scheme 1) by the insertion of an aryne into a C À S bond. Furthermore, the expected products are 2-quinolinones (3) which have provoked great interest in chemical and biological fields.[8] However, the challenge of this strategy lies in avoiding the addition of the strongly nucleophilic sulfur atom in the substrates to the arynes (Scheme 1 A), and instead favoring insertion of the arynes into the CÀS bond. [9,10] To the best of our knowledge, transition-metal-catalyzed CÀS bond cleavage for aryne insertion has been seldom reported.[10]Herein, we report that arynes can react with ketene dithioacetals by palladium-catalyzed C À S bond activation followed by cyclization to produce 2-quinolinones, but they remain inactive towards the nucleophilic S-containing group (Scheme 1 B). The new synthetic method is also highlighted by the versatile transformations of the 4-functionalized 2-quinolinones, which are not easily obtained starting from the cor...

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Section: Methodsmentioning

confidence: 99%

Palladium‐Catalyzed CS Activation/Aryne Insertion/Coupling Sequence: Synthesis of Functionalized 2‐Quinolinones

et al. 2014

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“…During our ongoing interest in ketene dithioacetal chemistry,8 the nucleophilicity of the α‐carbon atom of functionalized ketene dithioacetals (for example, 2 in Scheme ) has been well recognized 9,10. Taking into consideration the versatile reactivity of quinone monoketals 1 as electrophiles and ketene dithioacetals 2 as nucleophiles, the reaction between 1 and 2 was examined in this work.…”

Section: Methodsmentioning

confidence: 99%

Tin Tetrachloride‐Catalyzed Regiospecific Allylic Substitution of Quinone Monoketals: An Easy Entry to Benzofurans and Coumestans

Liu

Wang

et al. 2012

Adv Synth Catal

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A highly regioselective allylic substitution of quinone monoketals with a-oxoketene dithioacetals is achieved under the catalysis of only tin tetrachloride (1 mol%). The advantages of the reaction, including its simplicity, rapidity, low catalyst loading of inexpensive tin tetrachloride, mild conditions and; in particular, the regiospecificity, is proposed to be due to a pseudo-intramolecular process. This new synthetic method provides a facile [3 + 2] cycloaddition route to benzofurans and is highlighted by the synthesis of coumestans.

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“…The direct addition of the C-H bond of alkenes to alkynes catalyzed by transition metals has been explored by Trost,[8] Mitsudo/Kondo, [9] Murakami/Ito, [10] Yi, [11] Tsukuda, [12] Mori/Sato, [13] and Uemura. [14] Recently, a more efficient strategy, the direct oxidative cross-coupling of terminal alkenes catalyzed by Pd, Cu, or Rh, was developed by Gusevskaya, [15] Ishii, [16] Loh, [17] Yu, [18] Liu, [19] and 7984 nism of the intermolecular enamine migration pathway was proposed according to the results of a cross reaction. This method provides a new and direct approach for the synthesis of conjugated diene motifs.…”

Section: Introductionmentioning

confidence: 99%

Base‐Promoted Approach to Highly Functionalized Conjugated Dienes through Enamine Migration

et al. 2015

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Palladium‐Catalyzed Cross‐Coupling of Internal Alkenes with Terminal Alkenes to Functionalized 1,3‐Butadienes Using CH Bond Activation: Efficient Synthesis of Bicyclic Pyridones

Cited by 52 publications

References 46 publications

Palladium‐Catalyzed CS Activation/Aryne Insertion/Coupling Sequence: Synthesis of Functionalized 2‐Quinolinones

Palladium‐Catalyzed CS Activation/Aryne Insertion/Coupling Sequence: Synthesis of Functionalized 2‐Quinolinones

Tin Tetrachloride‐Catalyzed Regiospecific Allylic Substitution of Quinone Monoketals: An Easy Entry to Benzofurans and Coumestans

Base‐Promoted Approach to Highly Functionalized Conjugated Dienes through Enamine Migration

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