Route to 1,2,4- and 1,2,5-oxadiazole ring assemblies via a one-pot condensation/oxidation protocol

Teslenko, Fedor E.; Churakov, Artem I.; Larin, Alexander А.; Ananyev, Ivan V.; Ферштат, Леонид Л.; Махова, Нина Н.

doi:10.1016/j.tetlet.2020.151678

Cited by 13 publications

(4 citation statements)

References 50 publications

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“…Cleavage of the 1,2,4oxadiazoline ring in 56 furnishes the formation of (carbamoyl)furazans 57 (Scheme 18). 54 Although this reaction proceeds under solvent-free conditions, it requires a huge excess of an aldehyde (8 equiv.) which is not useful from the application point of view.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…The amidoxime functionality was annulated to give a 1,2,4-oxadiazole ring, while the 4-aminofuroxan moiety was converted into a (carbamoyl)furazan. Arguably, under elevated temperatures, 4-aminofuroxans 55 isomerize into 3-amino isomers 55′, which then add another molecule of the aldehyde followed by the generation of bicyclic struc- 54 Although this reaction proceeds under solvent-free conditions, it requires a large excess of the aldehyde (8 equiv); this is not useful from an application point of view.…”

Section: Short Review Synthesismentioning

confidence: 99%

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Five-Membered Hetarene N-Oxides: Recent Advances in Synthesis and Reactivity

Ферштат

Teslenko

2021

Synthesis

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Five-membered heterocyclic N-oxides attracted special attention due to their strong application potential in medicinal chemistry and advanced materials science. In this regard, novel methods for their synthesis and functionalization are constantly required. In this short review, recent state-of-the-art achievements in the chemistry of isoxazoline N-oxides, 1,2,3-triazole 1-oxides and 1,2,5-oxadiazole 2-oxides are briefly summarized. Main routes to transition-metal-catalyzed and metal-free functionalization protocols along with mechanistic considerations are outlined. Transformation patterns of the hetarene N-oxide rings as precursors to other nitrogen heterocyclic systems are also presented.

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Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Short Review Synthesismentioning

confidence: 99%

Five-Membered Hetarene N-Oxides: Recent Advances in Synthesis and Reactivity

Ферштат

Teslenko

2021

Synthesis

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“…The type of the formed heterocyclic core depends mainly on the structure of the electrophile. In particular, the coupling of amidoximes with carbonyl-based compounds such as aldehydes [ 7 , 8 , 9 ], carboxylic acids [ 10 , 11 , 12 ], and their derivatives (esters [ 13 , 14 , 15 , 16 ], anhydrides [ 17 , 18 , 19 , 20 ], as well as acyl chlorides [ 21 , 22 , 23 , 24 ]) usually results in 1,2,4-oxadiazoles. In this case, both nucleophilic centers of amidoxime (NOH and NH 2 groups) attack the same carbon atom of the electrophile ( Scheme 1 A).…”

Section: Introductionmentioning

confidence: 99%

Unusual Formation of 1,2,4-Oxadiazine Core in Reaction of Amidoximes with Maleic or Fumaric Esters

et al. 2022

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We have developed a simple and convenient method for the synthesis of 3-aryl- and 3-hetaryl-1,2,4-oxadiazin-5-ones bearing an easily functionalizable (methoxycarbonyl)methyl group at position 6 via the reaction of aryl or hetaryl amidoximes with maleates or fumarates. The conditions for this reaction were optimized. Different products can be synthesized selectively in good yields depending on the base used and the ratio of reactants: substituted (1,2,4-oxadiazin-6-yl)acetic acids, corresponding methyl esters, or hybrid 3-(aryl)-6-((3-(aryl)-1,2,4-oxadiazol-5-yl)methyl)-4H-1,2,4-oxadiazin-5(6H)-ones. The reaction is tolerant to substituents’ electronic and steric effects in amidoximes. As a result, a series of 2-(5-oxo-3-(p-tolyl)-5,6-dihydro-4H-1,2,4-oxadiazin-6-yl)acetic acids, their methyl esters, and 1,2,4-oxadiazoles based on them were prepared and characterized by HRMS, 1H, and 13C NMR spectroscopy. The structures of three of them were elucidated with X-ray diffraction.

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“…For example, molecular ensembles containing oxadiazole and triazole rings were obtained by the reaction of triazole carboxylic acid chlorides with N′-hydroxybenzimidamides. 11 Among the different strategies available for the synthesis of 1,2,4-oxadiazole derivatives, the more popular procedures involve reactions of amidoximes with carboxylic acids, [12][13][14] carboxylic acid chlorides, 15,16 dicarboxylic acid anhydrides, 17,18 aldehydes, 19 Erlenmeyer azlactones, 20 protected amino acids, 21 benzoyl cyanides, 22 nitrilium salts, 23 and oxidative cyclization by DDQ. 24 The formation of this scaffold was also accomplished by the reaction of hydroximoyl chloride with aryl thiocyanates, 25,26 hydroxylamine with cyanamides, 27 and by one-pot reactions of hydroxylamine involving either aryl isothiocyanates and amidines 28 or nitriles and Meldrum's acid.…”

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confidence: 99%

1,3-Dipolar Cycloaddition Reaction of Nitrile Oxide to Thiocyanates: An Efficient and Eco-Friendly Synthesis of N-Aryl-2-((3-aryl-1,2,4-oxadiazol-5-yl)thio)acetamides

Nair,

Radhakrishna,

Khatik

2024

Synthesis

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An efficient and eco-friendly procedure was developed for the synthesis of N-aryl-2-((3-aryl-1,2,4-oxadiazol-5-yl)thio)acetamides from N-aryl-2-thiocyanatoacetamides and substituted N-hydroxybenzimidoyl chlorides that were prepared easily from the commercially available anilines and aryl aldehydes, respectively. The N-aryl-2-thiocyanatoacetamide acts as a dipolarophile while the nitrile oxide formed in situ from substituted N-hydroxybenzimidoyl chloride acts as the nucleophilic partner in a 1,3-dipolar cycloaddition reaction mediated by triethylamine base in ethanol medium. The procedure affords excellent yields of desired products containing electron-withdrawing and electron-donating groups on the aromatic rings, in short reaction time with ease of operation. The procedure for the synthesis of scaffolds that are potentially valuable for their biological properties also offers the possibility of scale-up to higher quantities.

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Route to 1,2,4- and 1,2,5-oxadiazole ring assemblies via a one-pot condensation/oxidation protocol

Cited by 13 publications

References 50 publications

Five-Membered Hetarene N-Oxides: Recent Advances in Synthesis and Reactivity

Five-Membered Hetarene N-Oxides: Recent Advances in Synthesis and Reactivity

Unusual Formation of 1,2,4-Oxadiazine Core in Reaction of Amidoximes with Maleic or Fumaric Esters

1,3-Dipolar Cycloaddition Reaction of Nitrile Oxide to Thiocyanates: An Efficient and Eco-Friendly Synthesis of N-Aryl-2-((3-aryl-1,2,4-oxadiazol-5-yl)thio)acetamides

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