Palladium-catalyzed decarbonylative annulation of phthalimides with arynes: direct construction of phenanthridinones

Meng, Yan-Yu; Si, Xiao-Ju; Song, Yuanyuan; Zhou, Huimin; Xu, Fen

doi:10.1039/c9cc04868e

Cited by 28 publications

(7 citation statements)

References 46 publications

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“…Several methodologies have been reported in the literature for the synthesis of phenanthridinones via either transition metal catalysis (Pd, Rh, Cu) or radical-mediated catalysis − either via C–C/C–N bond formation (I, III, IV) , or via aminocarbonylation/CO insertion (II) (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Organocatalyst in Direct C(_sp²)–H Arylation of Unactivated Arenes: [1-(2-Hydroxyethyl)-piperazine]-Catalyzed Inter-/Intra-molecular C–H Bond Activation

et al. 2020

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This article describes the identification of 1-(2-hydroxyethyl)-piperazine as a new, cost-effective, highly efficient organocatalyst, which promotes both inter-and intra-molecular direct C( sp 2 )−H arylations of unactivated arenes in the presence of potassium tert-butoxide. While the inter-molecular C−H arylation of unactivated benzenes with aryl halides (Ar−X; X = I, Br, Cl) toward biaryl syntheses underwent smoothly in the presence of only 10 mol % organocatalyst, the intra-molecular C−H arylation catalytic system composed of 40 mol % each of the catalyst and the additive (4-dimethylaminopyridine (DMAP)). The novel catalyst was also able to perform both inter-and intra-molecular direct arylations simultaneously in a single pot. The mechanistic studies confirmed the involvement of aryl radical anions and proceeded via a single-electron-transfer (SET) mechanism. The large substrate scope, high functional group tolerance, competition experiments, gram-scale synthesis, and kinetic studies further highlight the importance and versatile nature of the methodology as well as the compatibility of the new catalyst. To the best of our knowledge, this is the first report on any organocatalyst that reported detailed investigations of both inter-and intra-molecular direct C( sp 2 )−H arylations of unactivated arenes in a single representation.

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Section: Resultsmentioning

confidence: 99%

Organocatalyst in Direct C(_sp²)–H Arylation of Unactivated Arenes: [1-(2-Hydroxyethyl)-piperazine]-Catalyzed Inter-/Intra-molecular C–H Bond Activation

et al. 2020

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“…In a study carried out by Harmata et al on the preparation of benzofused benzothiazines from o -halo sulfoximines, they also reported Pd-catalyzed annulation examples, albeit in low yields . Recently, Meng, Xu, and co-workers achieved a Pd-catalyzed decarbonylative annulation of phthalimides 10-91 with o -silylaryl triflates, affording phenanthridinones 10-92 with good functional group tolerance (Scheme b) . Mechanistically, the catalytic cycle involves (1) oxidative addition of Pd(0) into an imide N–CO bond to generate intermediate 10-93 ; (2) decarbonylation to give a five-membered palladacycle 10-94 ; (3) aryne insertion to form a seven-membered palladacycle 10-95 ; and (4) reductive elimination to yield 10-92 along with the regeneration of Pd(0) species.…”

Section: Transition-metal-catalyzed Reactionsmentioning

confidence: 99%

o-Silylaryl Triflates: A Journey of Kobayashi Aryne Precursors

2021

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Arynes are among the most active organic intermediates and have found numerous applications in expeditious preparation of substituted arenes. In the past 20 years, chemists have witnessed a resurgence in aryne chemistry, which is mainly attributed by the extensive utilization of Kobayashi's method, a fluoride-induced removal of the TMS group with concomitant departure of its ortho OTf group on o-silylaryl triflates. Nowadays, o-silylaryl triflates are the most frequently employed aryne precursors. This review provides an overview of the history of Kobayashi's method, its methodological achievements, and its applications in the synthesis of natural products, bioactive molecules, and polycyclic aromatic hydrocarbons.

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“…Multinuclear NMR spectroscopy showed that other coordinating solvents such as MeCN or DMSO also gave adducts tentatively assigned as 7·NCMe and 7·DMSO , but these could not be isolated as crystalline solids. Diamagnetic Pd analogues are known. − As shown in Scheme a), the C–H activation of 3 liberates 1 equiv of [AQ piv ]H ( 1a ), which was observed by 1 H NMR spectroscopy. The C–H activation 5 in the absence of added base also produced 1a , presumably because the t BuCO 2 H produced by deprotonation of the C–H bond protonates unreacted 5 , generating [AQ piv ]H ( 1a ), which lowers the yield.…”

Section: Results and Discussionmentioning

confidence: 98%

Mechanism of 8-Aminoquinoline-Directed Ni-Catalyzed C(sp³)–H Functionalization: Paramagnetic Ni(II) Species and the Deleterious Effect of Carbonate as a Base

Liu

Johnson

2021

Organometallics

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Studies into the mechanism of 8-aminoquinoline-directed nickel-catalyzed C(sp3)–H arylation with iodoarenes were carried out, to determine the catalyst resting state and optimize catalytic performance. Paramagnetic complexes undergo the key C–H activation step. The ubiquitous base Na2CO3 is found to hinder catalysis; replacement of Na2CO3 with NaO t Bu gave improved catalytic turnovers under milder conditions. Deprotonation of the 8-aminoquinoline derivative N-(quinolin-8-yl)pivalamide (1a) at the amide nitrogen using NaH, followed by reaction with NiCl2(PPh3)2 allowed for the isolation of complex Ni([AQpiv]-κN,N)2 (3) with chelating N-donors (where [AQpiv] = C9NH6NCO t Bu). Complex 3 is a four-coordinate disphenoidal high-spin Ni(II) complex, excluding short anagostic Ni-- t Bu hydrogen interactions. Complex 3 reacts with the paddle-wheel [Ph3PNi(μ-CO2 t Bu)2]2 (6·PPh 3 ) or t BuCO2H to give insoluble {[AQpiv]Ni(O2C t Bu)}2 (5). Dissolution of 5 in donor solvents L (L= DMSO and DMF) gave a paramagnetic intermediate assigned by NMR as [AQpiv]Ni(O2C t Bu)L (5·L) and equilibrium reformation of 3 and 6·L. DFT calculations support this equilibrium in solution. Both 3 and 5 undergo C–H activation at temperatures as low as 80 °C and in the presence of PR3 (PR3 = PPh3, P i Bu3) to give Ni(C9NH6NCOCMe2CH2-κN,N,C)PR3 (7·PR 3 ). The C–H functionalization reaction orders with respect to 7·P i Bu 3 , iodoarenes, and phosphines were determined. Hammett analysis using electronically different aryl iodides suggests a concerted oxidative addition mechanism for the C–H functionalization step; DFT calculations were also carried out to support this finding. When Na2CO3 is used as the base, the rate determination step for C–H functionalization appears to be 8-aminoquinoline deprotonation and binding to Ni. The carbonate anion was also observed to provide a deleterious NMR-inactive low-energy off-cycle resting state in catalysis. Replacement of Na2CO3 with NaO t Bu improved catalysis at milder conditions and made carboxylic acid and phosphine additives unnecessary. Complex 3 and its functionalized analogues were observed as the catalyst resting state under these conditions.

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Palladium-catalyzed decarbonylative annulation of phthalimides with arynes: direct construction of phenanthridinones

Abstract: A novel palladium-catalyzed decarbonylative annulation between phthalimides and arynes was well-established, affording phenanthridinone derivatives in moderate to good yields.

Cited by 28 publications

References 46 publications

Organocatalyst in Direct C(_sp²)–H Arylation of Unactivated Arenes: [1-(2-Hydroxyethyl)-piperazine]-Catalyzed Inter-/Intra-molecular C–H Bond Activation

Organocatalyst in Direct C(_sp²)–H Arylation of Unactivated Arenes: [1-(2-Hydroxyethyl)-piperazine]-Catalyzed Inter-/Intra-molecular C–H Bond Activation

o-Silylaryl Triflates: A Journey of Kobayashi Aryne Precursors

Mechanism of 8-Aminoquinoline-Directed Ni-Catalyzed C(sp³)–H Functionalization: Paramagnetic Ni(II) Species and the Deleterious Effect of Carbonate as a Base

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Palladium-catalyzed decarbonylative annulation of phthalimides with arynes: direct construction of phenanthridinones

Abstract: A novel palladium-catalyzed decarbonylative annulation between phthalimides and arynes was well-established, affording phenanthridinone derivatives in moderate to good yields.

Cited by 28 publications

References 46 publications

Organocatalyst in Direct C(sp2)–H Arylation of Unactivated Arenes: [1-(2-Hydroxyethyl)-piperazine]-Catalyzed Inter-/Intra-molecular C–H Bond Activation

Organocatalyst in Direct C(sp2)–H Arylation of Unactivated Arenes: [1-(2-Hydroxyethyl)-piperazine]-Catalyzed Inter-/Intra-molecular C–H Bond Activation

o-Silylaryl Triflates: A Journey of Kobayashi Aryne Precursors

Mechanism of 8-Aminoquinoline-Directed Ni-Catalyzed C(sp3)–H Functionalization: Paramagnetic Ni(II) Species and the Deleterious Effect of Carbonate as a Base

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Organocatalyst in Direct C(_sp²)–H Arylation of Unactivated Arenes: [1-(2-Hydroxyethyl)-piperazine]-Catalyzed Inter-/Intra-molecular C–H Bond Activation

Organocatalyst in Direct C(_sp²)–H Arylation of Unactivated Arenes: [1-(2-Hydroxyethyl)-piperazine]-Catalyzed Inter-/Intra-molecular C–H Bond Activation

Mechanism of 8-Aminoquinoline-Directed Ni-Catalyzed C(sp³)–H Functionalization: Paramagnetic Ni(II) Species and the Deleterious Effect of Carbonate as a Base