C–N Coupling via Antiaromatic Endocyclic Nitrenium Ions

Bera, Shyamal Kanti; Alam, Toufique; Mal, Prasenjit

doi:10.1021/acs.joc.9b01921

Cited by 20 publications

(39 citation statements)

References 52 publications

(90 reference statements)

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“… 94 † † Importantly, this approach is not limited to the oxidation of carboxamides, but can be similarly applied to nitrogen atoms in benzimidazoles. 162 α-Tertiary amines may undergo a 1,2-alkyl shift onto the nitrenium species. The thus generated iminium ion can be subsequently trapped by sodium cyanoborohydride as the secondary nucleophile.…”

Section: Cross-nucleophile Coupling Using Iodine( III )mentioning

confidence: 99%

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Recent discoveries on the structure of iodine(iii) reagents and their use in cross-nucleophile coupling

Bauer

Maulide

2021

Chem. Sci.

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Section: Cross-nucleophile Coupling Using Iodine( III )mentioning

confidence: 99%

“… † Importantly, this approach is not limited to the oxidation of carboxamides, but can be similarly applied to nitrogen atoms in benzimidazoles. 162 …”

Section: Cross-nucleophile Coupling Using Iodine( III )mentioning

confidence: 99%

Recent discoveries on the structure of iodine(iii) reagents and their use in cross-nucleophile coupling

Bauer

Maulide

2021

Chem. Sci.

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“…Recently in 2019, Mal and co‐workers disclosed a metal‐free C−N coupling reaction to construct various benzimidazole‐fused phenanthridine derivatives 338 through a nitrenium ion intermediate using readily available iodine(III) reagent PhI(OCOCF 3 ) 2 [101] . This C−N cross‐coupling reaction has avoided inexpensive catalysts and harsh conditions.…”

Section: Synthesis Of Phenanthridinesmentioning

confidence: 99%

“…Recently in 2019, Mal and co-workers disclosed a metal-free C À N coupling reaction to construct various benzimidazole-fused phenanthridine derivatives 338 through a nitrenium ion intermediate using readily available iodine(III) reagent PhI(OCOCF 3 ) 2 . [101] This CÀ N cross-coupling reaction has avoided inexpensive catalysts and harsh conditions. Additionally, ambient conditions and commercially available iodine reagent made this synthetic protocol more attractive towards the construction of heterocycles (Scheme 119).…”

Section: Using Iodonium Saltsmentioning

confidence: 99%

Recent Trends in the Synthesis and Mechanistic Implications of Phenanthridines

et al. 2021

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Phenanthridine derivatives are one of the most intensively studied families of biologically active compounds. There has been considerable scientific interest in the turn of this century in the synthesis of these N‐containing heterocycles as they are prevalent in many alkaloids and also possess striking biological activities including antibacterial, antifungal, antitumor activities. In this regard, a number of synthetic approaches toward the construction of phenanthridine moieties with various substituents, and to increase their yield have been developed by the synthetic organic community. Even though many researchers have developed various innovative methods for the synthesis of phenanthridine derivatives for the past few years, still there is substantial scope for the discovery of novel synthetic methods. In this review, the latest developments in the diverse synthetic strategies of phenanthridine derivatives in the presence and absence of metals were described. The present review also enlightens the use of different reagents, the diversity of the substrates identified, and the plausible mechanisms unravelled towards the construction of these biologically relevant scaffolds.

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“…Mal et al reported the use of PIFA (PhI(OCOCF 3 ) 2 ) for six-membered aromatic substitutions via a proposed nitrenium ion intermediate ( Scheme 36 a) [ 112 ]. Cho et al made the reaction at N -1 of benzimidazole intermolecular, with addition onto aryl isocyanate and aromatic substitution of the carbamoyl-NH to give fused quinazolinones and pyrimidinones ( Scheme 36 b) [ 113 ].…”

Section: Syntheses Of Ring-fused Benzimidazoles and Imidazobenzimidazolesmentioning

confidence: 99%

Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles

et al. 2021

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This review article provides a perspective on the synthesis of alicyclic and heterocyclic ring-fused benzimidazoles, imidazo[4,5-f]benzimidazoles, and imidazo[5,4-f]benzimidazoles. These heterocycles have a plethora of biological activities with the iminoquinone and quinone derivatives displaying potent bioreductive antitumor activity. Synthesis is categorized according to the cyclization reaction and mechanisms are detailed. Nitrobenzene reduction, cyclization of aryl amidines, lactams and isothiocyanates are described. Protocols include condensation, cross-dehydrogenative coupling with transition metal catalysis, annulation onto benzimidazole, often using CuI-catalysis, and radical cyclization with homolytic aromatic substitution. Many oxidative transformations are under metal-free conditions, including using thermal, photochemical, and electrochemical methods. Syntheses of diazole analogues of mitomycin C derivatives are described. Traditional oxidations of o-(cycloamino)anilines using peroxides in acid via the t-amino effect remain popular.

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C–N Coupling via Antiaromatic Endocyclic Nitrenium Ions

Cited by 20 publications

References 52 publications

Recent discoveries on the structure of iodine(iii) reagents and their use in cross-nucleophile coupling

Recent discoveries on the structure of iodine(iii) reagents and their use in cross-nucleophile coupling

Recent Trends in the Synthesis and Mechanistic Implications of Phenanthridines

Advances in the Synthesis of Ring-Fused Benzimidazoles and Imidazobenzimidazoles

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