Synthesis of 1,4-diphenyl-3-phenylimino-1,2-dihydro-1,2,4-triazolium hydroxide (Nitron)

Кривенько, А. П.; Morozova, N. A.

doi:10.1134/s1070427206030396

Cited by 8 publications

(3 citation statements)

References 3 publications

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“…Using the most recently reported literature synthesis of Nitron 2 (ref. 43 ), four additional derivatives 11 – 13 ( Fig. 6 ) were prepared (see Supplementary Methods ).…”

Section: Resultsmentioning

confidence: 99%

New Blatter-type radicals from a bench-stable carbene

et al. 2017

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Stable benzotriazinyl radicals (Blatter's radicals) recently attracted considerable interest as building blocks for functional materials. The existing strategies to derivatize Blatter's radicals are limited, however, and synthetic routes are complex. Here, we report that an inexpensive, commercially available, analytical reagent Nitron undergoes a previously unrecognized transformation in wet acetonitrile in the presence of air to yield a new Blatter-type radical with an amide group replacing a phenyl at the C(3)-position. This one-pot reaction of Nitron provides access to a range of previously inaccessible triazinyl radicals with excellent benchtop stabilities. Mechanistic investigation suggests that the reaction starts with a hydrolytic cleavage of the triazole ring followed by oxidative cyclization. Several derivatives of Nitron were prepared and converted into Blatter-type radicals to test the synthetic value of the new reaction. These results significantly expand the scope of using functionalized benzotriazinyls as stable radical building blocks.

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“…Using the most recently reported literature synthesis of Nitron 2 (ref. 43 ), four additional derivatives 11 – 13 ( Fig. 6 ) were prepared (see Supplementary Methods ).…”

Section: Resultsmentioning

confidence: 99%

New Blatter-type radicals from a bench-stable carbene

et al. 2017

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“…Because aminoguanidine free bases are prone to decomposition during isolation and purification, the more stable aminoguanidine hydrochlorides 3 d , i , m were isolated (Scheme 1, Method A and Scheme S1). Attempts at the cyclization of compounds 3 d , i , m by procedures used for Nitron synthesis, such as heating with formic acid at 175 °C [17a] or stepwise condensation with formaldehyde and subsequent oxidation, [17b–d,18] were unsuccessful, and only tarred inseparable mixtures were obtained (Table S1, Entries 1,2). The use of formaldehyde in combination with trimethylchlorosilane led to only moderate yields of product 4 i (Table S1, Entry 3).…”

Section: Resultsmentioning

confidence: 99%

Base‐Ionizable Anionic NHC Ligands in Pd‐catalyzed Reactions of Aryl Chlorides

Chernenko,

Baydikova,

Kutyrev

et al. 2024

ChemCatChem

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Aryl chlorides, due to their affordability and accessibility, are preferred reagents in Pd‐catalyzed arylation reactions. However, the reactivity of aryl chlorides is often reduced compared to aryl bromides and iodides due to the significantly higher barriers of the oxidative addition stage. This research introduces a novel design for NHC ligands, which notably enhances the efficiency of Pd/NHC catalytic systems in reactions where oxidative addition of aryl chloride is the rate‐limiting step. This design leverages a synergy between specific steric characteristics and the anionic nature of the newly fashioned 1,2,4‐triazol‐5‐ylidene ligands. These ligands, inspired by Nitron‐type designs, can be ionized under basic conditions due to their NH‐acidic aryl(alkyl)amino groups. Detailed experimental and DFT studies revealed that the deprotonation of these NHCs promotes electron donation to the metal center, promoting the oxidative addition of aryl chloride. The specially optimized ATPr ligand, featuring 2,6‐diisopropylphenyl groups, displayed remarkable catalytic efficacy in the Suzuki‐Miyaura reaction and improved outcomes in ketone α‐arylation and Buchwald‐Hartwig reactions with unactivated aryl chlorides. The insights and strategies established in this study provide rational considerations for further advancements in NHC designs and their applications in metal‐catalyzed reactions.

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“…The first example of the latter class of molecules is provided by 1,3,4-triphenyl-1,2,4-triazol-5-ylidene, which is often referred to as Enders carbene (Figure ). Conceptually related to Enders carbene is a derivative that features an exocyclic 4-NHPh rather than 4-Ph substituent (Figure ); however, while this NHC has not been isolated, its long-known mesoionic tautomer, (1,4-diphenyl-1,2,4-triazol-4-ium-3-yl)phenylazanide (Nitron), − exhibits reactivity that provides access to the carbene form (Figure ). − For example, Nitron reacts with elemental sulfur to afford a thione derivative; likewise, Nitron has been used to obtain several metal complexes of the type (Nitron NHC )ML n (M = Ru, Rh, Cu, Ag, Au) that feature the 1,2,4-triazol-5-ylidene ligand, Nitron NHC . − In view of this reactivity, Nitron has been referred to as a “crypto-NHC”. , Here, we describe further applications of Nitron as a crypto-NHC to afford 1,2,4-triazolylidene compounds of nickel, palladium, and iridium, together with their structural and catalytic properties.…”

Section: Introductionmentioning

confidence: 99%

N-Heterocyclic Carbene Complexes of Nickel, Palladium, and Iridium Derived from Nitron: Synthesis, Structures, and Catalytic Properties

et al. 2021

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The mesoionic compound (1,4-diphenyl-1,2,4-triazol-4-ium-3-yl)phenylazanide, commonly referred to as Nitron, has been employed as a "crypto-NHC" to afford 1,2,4-triazolylidene compounds of nickel, palladium, and iridium. Specifically, Nitron reacts with NiBr 2 , PdCl 2 , and [Ir(COD)Cl] 2 to afford the Nheterocyclic carbene complexes (Nitron NHC ) 2 NiBr 2 , (Nitron NHC ) 2 PdCl 2 , and (Nitron NHC )Ir(COD)Cl, respectively. The lattermost compound reacts with (i) CO to afford the dicarbonyl compound (Nitron NHC )Ir(CO) 2 Cl and (ii) CO, in the presence of PPh 3 , to afford the monocarbonyl compound (Nitron NHC )Ir(PPh 3 )-(CO)Cl. Structural studies on (Nitron NHC )Ir(COD)Cl and (Nitron NHC )Ir(CO) 2 Cl indicate that Nitron NHC has a stronger trans influence than does Cl; furthermore, IR spectroscopic studies on (Nitron NHC )Ir(CO) 2 Cl indicate that Nitron NHC is electronically similar to the structurally related Enders carbene but is less electron donating than imidazol-2-ylidenes with aryl substituents. Significantly, the Nitron NHC ligand affords catalytic systems, as illustrated by the ability of (Nitron NHC )Ir(CO) 2 Cl to effect (i) the dehydrogenation of formic acid, (ii) aldehyde hydrosilylation, (iii) dehydrocoupling of hydrosilanes and alcohols, and (iv) ketone reduction via transfer hydrogenation.

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Synthesis of 1,4-diphenyl-3-phenylimino-1,2-dihydro-1,2,4-triazolium hydroxide (Nitron)

Cited by 8 publications

References 3 publications

New Blatter-type radicals from a bench-stable carbene

New Blatter-type radicals from a bench-stable carbene

Base‐Ionizable Anionic NHC Ligands in Pd‐catalyzed Reactions of Aryl Chlorides

N-Heterocyclic Carbene Complexes of Nickel, Palladium, and Iridium Derived from Nitron: Synthesis, Structures, and Catalytic Properties

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