Synthesis of 2<i>H</i>‐Indazoles <i>via</i> Tandem Palladium‐Catalyzed Deacylative Cross‐Coupling and Denitrogenative Cyclization of 2‐Iodoazoarenes and 2‐Iodoaryltriazenes with Acyldiazoacetates in One‐Pot

Yong, Woo‐Soon; Park, Sangjune; Yun, Hyunsik; Lee, Phil Ho

doi:10.1002/adsc.201600351

Cited by 35 publications

(8 citation statements)

References 56 publications

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“…Lee and co-workers developed a synthetic method to prepare a wide range of 2H-indazoles via Pd-catalyzed deacylative cross-coupling reaction of 2-iodoazoarenes with acyldiazoacetate (Scheme 5). [19] Mechanistically formation of indazole involves two catalytic cycles. The first cycle involves Pd (PPh 3 ) 4 -catalyzed deacylative coupling between diazoacetate and 2-iodoazoarenes in a basic medium.…”

Section: Pd-catalyzed Synthesis Of Indazolesmentioning

confidence: 99%

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Transition‐Metal‐Catalyzed Syntheses of Indazoles

et al. 2020

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Indazole is an important heterocyclic scaffold exhibiting a wide range of biological and pharmacological properties and plays a crucial role in drug design. In recent years, indazoles have gained attention in materials chemistry owing to their promising photophysical properties. The biomedical importance and natural rarity inspire the development of new practical syntheses of the indazole core. In this review, we are presenting a comprehensive overview of recent developments in the transition metal-catalyzed synthesis of indazole during the last decade.

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Section: Pd-catalyzed Synthesis Of Indazolesmentioning

confidence: 99%

“…Lee and co‐workers developed a synthetic method to prepare a wide range of 2 H ‐indazoles via Pd‐catalyzed deacylative cross‐coupling reaction of 2‐iodoazoarenes with acyldiazoacetate (Scheme ) . Mechanistically formation of indazole involves two catalytic cycles.…”

Section: Pd‐catalyzed Synthesis Of Indazolesmentioning

confidence: 99%

Transition‐Metal‐Catalyzed Syntheses of Indazoles

et al. 2020

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“…Recently, there have been a few remarkable reports on the one‐pot syntheses of 2 H ‐indazoles. The synthesis involves a copper‐catalyzed three‐component reaction (Scheme a), condensation, and Cadogan reductive cyclization using organophosphorus reagents (Scheme b),– or tandem palladium‐catalyzed deacylative cross‐coupling and denitrogenative cyclization (Scheme c) . However, these reactions have inherent limitations such as the need for elevated temperatures and transition‐metal reagents in addition to the narrow substrate scope (in particular, the difficulty in introducing various substituents at the C3‐position of indazole).…”

Section: Figurementioning

confidence: 99%

Room‐Temperature, Metal‐Free, and One‐Pot Preparation of 2H‐Indazoles through a Mills Reaction and Cyclization Sequence

Kondo

Takizawa

Jiang

et al. 2019

Chemistry A European J

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The Mills reaction and cyclizationo fr eadily available 2-aminobenzyla lcohols and nitrosobenzenes using thionyl bromidep rovided 2H-indazoles in up to 88 %y ields. In the metal-free process, acetic acid played a crucial role for the both Mills reactiona nd cyclization. A brominated 2H-indazole could also be obtained through the one-pot sequence.Indazoles are au seful class of N-heteroaromatic compounds because they are crucial structural motifs of various biologically active compounds, [1] particularly,b ioisosteres for indoles and benzimidazoles. [1e] Al arge number of 2H-indazole derivatives have been demonstratedf or use as important biologically active compounds, [1c-h] such as niraparib (PARP inhibitor) [2] and liver Xr eceptor agonist, [3] in addition to fluorescent agents for cellular imaging in the field of chemical biology (Figure 1). [4] Because of the high utility of N-substituted indazoles, much attention has been devoted to establish novel and efficient strategies for their preparation. However,N -functionalization of indazoles often results in am ixture of 1H-a nd 2H-indazoles because the latter is thermodynamically disfavored in comparison with the former (energy difference between them is 2.3 kcal mol À1 ). [1e, 5, 6] Therefore, regioselective construction of the 2H-indazole skeleton remains ac hallenging task in organic synthesis. [4a, 7] Recently,t here have been af ew remarkable reports on the one-pot syntheses of 2H-indazoles. The synthesis involves a copper-catalyzedt hree-component reaction (Scheme 1a), [7a,b] Chem. Eur.

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“…Recently, it has been reported a tandem Pd‐catalyzed deacylative cross‐coupling followed by denitrogenative cyclization of acetyl diazoacetates with 2‐iodoazoarenes and 2‐iodoaryltriazenes giving 2 H ‐indazoles (Scheme ) . The deacylative process took place under mild reaction conditions using 5 mol‐% of Pd(PPh 3 ) 4 as catalyst and NaOH as base at room temp.…”

Section: Other Deacylative Reactionsmentioning

confidence: 99%

Deacylative Reactions: Synthetic Applications

et al. 2018

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Herein we introduce the recent developments of a new strategy based on deacylative alkylation (DaA) reactions for the generation of quaternary stereocenters based on the in situ preparation and functionalization of enolates under very mild reaction conditions. Palladium‐catalyzed deacylative allylation and benzylation reactions of carbon nucleophiles are performed with the corresponding alcohols. This methodology has been applied to the synthesis of the calcium ion channel blocker verapamil, the antiviral (+)‐hamigeran B, several oxindole precursors of esermethole, horsfiline, physostigmine, phenserine, meso‐folicanthine, meso‐chinonanthine and the dimer cyclotriptamine alkaloids. Base‐promoted deacylative reactions enable the functionalization of 2‐oxindole enolates at the 3‐position with alkyl halides and electrophilic alkenes. In the presence of oxygen or air, 3‐hydroxy‐2‐oxindoles are prepared by deacylative oxidation. Detrifluoroacylative reactions are promoted by a base generating fluoroenolates, which can participate in aldol, Mannich and Michael reactions for the preparation of important fluorinated intermediates. Finally, palladium‐catalyzed deacylative cross‐coupling of acetyl diazoacetates and phosphonates with aryl iodides let to the formation of aryl diazoacetates and phosphonates, respectively. The same process, with 2‐iodoazoarenes and 2‐iodoaryltriazenes, gives 2H‐indazoles, which are important pharmacophores.

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Synthesis of 2H‐Indazoles via Tandem Palladium‐Catalyzed Deacylative Cross‐Coupling and Denitrogenative Cyclization of 2‐Iodoazoarenes and 2‐Iodoaryltriazenes with Acyldiazoacetates in One‐Pot

Cited by 35 publications

References 56 publications

Transition‐Metal‐Catalyzed Syntheses of Indazoles

Transition‐Metal‐Catalyzed Syntheses of Indazoles

Room‐Temperature, Metal‐Free, and One‐Pot Preparation of 2H‐Indazoles through a Mills Reaction and Cyclization Sequence

Deacylative Reactions: Synthetic Applications

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