Base-promoted C–C bond cleavage for the synthesis of 2,3,4-trisubstituted pyrroles from <i>N</i>-propargyl β-enaminones

Ge, Bailu; Lv, Weiwei; Yu, Jia; Xiao, Shuzhang; Cheng, Guolin

doi:10.1039/c8qo00801a

Cited by 21 publications

(8 citation statements)

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“…7 Inspired by Lei's work, we questioned whether this open shell deacylative α-cupration mechanism might be translated to other transition metals, such as ruthenium, thereby allowing catalytic formation of alkyl Ru intermediates that can be captured by suitable coupling partners. In continuation of our research on C–C(CO) bond cleavage reactions,8 herein we disclose the first ruthenium-catalyzed deacylative annulation of 1,3-diones with sulfoxonium ylides (Scheme 1c). This method provides a practical and mild synthetic route to substituted furans,9 which are essential structural moieties in many biologically active compounds, natural products, and functional materials 10…”

Section: Introductionmentioning

confidence: 96%

Ruthenium(ii)-catalyzed chemoselective deacylative annulation of 1,3-diones with sulfoxonium ylides via C–C bond activation

Wen

et al. 2019

Chem. Sci.

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The first successful example of deacylative annulation of 1,3-diones with sulfoxonium ylides was achieved through Ru(II)-catalyzed C-C bond activation. The excellent chemoselectivity and broad substrate scope render this method a practical and versatile approach for the preparation of (hetero)aryl and alkenyl substituted furans, which are valuable units in many biologically active compounds and functional materials. A preliminary mechanistic study reveals that this process involves a deacylative a-ruthenation to generate key alkyl Ru(II) intermediates with the release of a benzoic acid fragment.Scheme 2 Scope of 1,3-diones. Reaction conditions: 1 (0.1 mmol), 2a (0.2 mmol), MesCO 2 Li (0.15 mmol), and [RuCl 2 (p-cymene)] 2 (5 mol%) in toluene (2 mL) at 120 C in air for 24 h. This journal isScheme 3 Scope of sulfoxonium ylides. Reaction conditions: 1a (0.1 mmol), 2 (0.2 mmol), MesCO 2 Li (0.15 mmol), and [RuCl 2 (p-cymene)] 2 (5 mol%) in toluene (2 mL) at 120 C in air for 24 h.Scheme 4 Gram-scale reactions and control experiments.9106 | Chem. Sci., 2019, 10, 9104-9108This journal is

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Section: Introductionmentioning

confidence: 96%

Ruthenium(ii)-catalyzed chemoselective deacylative annulation of 1,3-diones with sulfoxonium ylides via C–C bond activation

Wen

et al. 2019

Chem. Sci.

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“…Pioneering studies of Cacchi and Fabrizi and Saito and Hanzawa opened the way for the synthesis of type 1 and 2 pyrrole derivatives, respectively . Later, other research groups were also involved in the synthesis of such pyrrole derivatives . Besides, the Cheng research group reported a ring-closing carbonyl-allene metathesis reaction of N -propargyl β-enaminones, which provided 2,4-disubstituted pyrroles, called as type 3, via the intermediacy of dihydropyrrole-fused oxetanes (Scheme a, lower left) .…”

Section: Introductionmentioning

confidence: 99%

One-Pot Synthesis of 2-Acetyl-1H-pyrroles from N-Propargylic β-Enaminones via Intermediacy of 1,4-Oxazepines

et al. 2021

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A one-pot two-step protocol for the synthesis of 2-acetyl-1H-pyrroles from N-propargylic β-enaminones was described. When treated with zinc chloride in refluxing chloroform, N-propargylic β-enaminones produced in situ 2-methylene-2,3-dihydro-1,4-oxazepines, which, upon further refluxing in methanol with zinc chloride, afforded 2-acetyl-1H-pyrroles. The process was found to be general for a wide variety of N-propargylic β-enaminones and yielded a diverse range of 2-acetyl-1H-pyrroles in good to high yields with large substrate scope and good functional group tolerance. This operationally easy method may provide a rapid access to functionalized 2-acetyl-1H-pyrroles of pharmacological interest.

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“…Inspired by the works of Li and Ackermann, we questioned whether sulfoxonium ylides could be able to serve as both arenes and coupling partners in transition-metal-catalyzed C–H activation. As our ongoing interest in C–H activation and C–C cleavage, herein, we disclose a ruthenium(II)-catalyzed dual C–H/C–C activation of sulfoxonium ylides for the synthesis of isocoumarins (Scheme d) …”

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confidence: 99%

Ruthenium(II)-Catalyzed Construction of Isocoumarins via Dual C–H/C–C Activation of Sulfoxonium Ylides

et al. 2019

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A ruthenium(II)-catalyzed annulation between two molecules of sulfoxonium ylides is achieved, generating a variety of substituted isocoumarins in reasonable yields. This strategy features dual C−H/C−C activation in one pot and has a wide substrate scope and good functional group tolerance.I socoumarin and its derivatives are important natural lactones, which are generally found in natural products as a basic structure. 1 It was found that compounds with an isocoumarin structure have a certain physiological activity, 2 which are widely used in the treatment of cancer, 3 allergies, 4 sterilization, 5 and other aspects. 6 In addition, they could be used as key synthetic intermediates in drug discovery. 7 Thus, the synthesis of compounds with such a skeleton has attracted great interest. 8 Among the many synthetic methods to access these compounds, the transition-metal-catalyzed C−H activation/annulation cascade reactions of benzoic acid derivatives with coupling partners represent one of the most powerful and straightforward methods to isocoumarins. However, the coupling partners are commonly limited to internal alkynes (Scheme 1a). 9 The use of coupling partners other than internal alkynes will greatly enhance the scope of metal-catalyzed synthesis of isocoumarins.Sulfoxonium ylides are carbene precursors that are easier to prepare and more stable and safer than diazonium compounds. 10 Sulfoxonium ylides have been used as alkylating reagents in a variety of reactions. 11−15 Since the first example of rhodium(III)-catalyzed C−H alkylation of arenes with sulfoxonium ylides was independently discovered by Aïssa 11 and Li, 12 sulfoxonium ylides have been widely used as alkylating reagents in transition-metal-catalyzed C−H functionalization of a range of arenes. 13 Recently, Li's work illuminated the method of synthesizing isocoumarins from Nmethoxybenzamides, using sulfoxonium ylides as coupling partners and rhodium(III) as a catalyst (Scheme 1b). 14 Subsequently, a method for the formation of isocoumarins via ruthenium(II)-catalyzed C−H activation/annulation of benzoic acids and sulfoxonium ylides was reported by Ackermann (Scheme 1c). 15 Inspired by the works of Li and Ackermann, we questioned whether sulfoxonium ylides could be able to serve as both arenes 16 and coupling partners in transition-metal-catalyzed C−H activation. As our ongoing interest in C−H activation 17 and C−C cleavage, 18 herein, we disclose a ruthenium(II)-catalyzed dual C−H/C−C activation of sulfoxonium ylides for the synthesis of isocoumarins (Scheme 1d). 19 We initiated our investigation on the model reaction of sulfoxonium ylide (1a) to optimize various reaction parameters. The results are summarized in Table 1. To our delight, under reaction conditions using [RuCl 2 (p-cymene)] 2 as the catalyst, 2,4,6-trimethylbenzoic acid (MesCO 2 H) being an additive, and Na 3 PO 4 as the base in HFIP at 110 °C under an air atmosphere for 24 h, the desired product (2a) was obtained in 78% yield (entry 1). Investigations on various solvents indicat...

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Base-promoted C–C bond cleavage for the synthesis of 2,3,4-trisubstituted pyrroles from N-propargyl β-enaminones

Abstract: The synthesis of 2,3,4-trisubstituted pyrroles via base-promoted C–C bond cleavage reaction of N-propargyl β-enaminones is reported.

Cited by 21 publications

References 75 publications

Ruthenium(ii)-catalyzed chemoselective deacylative annulation of 1,3-diones with sulfoxonium ylides via C–C bond activation

Ruthenium(ii)-catalyzed chemoselective deacylative annulation of 1,3-diones with sulfoxonium ylides via C–C bond activation

One-Pot Synthesis of 2-Acetyl-1H-pyrroles from N-Propargylic β-Enaminones via Intermediacy of 1,4-Oxazepines

Ruthenium(II)-Catalyzed Construction of Isocoumarins via Dual C–H/C–C Activation of Sulfoxonium Ylides

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