Preparation of N-hydroxyazoles by oxidation of azoles

Begtrup, Mikael; Vedsø, Per

doi:10.1039/p19950000243

Cited by 43 publications

(39 citation statements)

References 18 publications

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“…The hydrochloride [8,10,14] and hydrobromide [9] of 1-hydroxyimidazole are known, but no crystal structure has been reported. We determined the structures of these known compounds and the new salts, sulfate and nitrate.…”

Section: Resultsmentioning

confidence: 99%

“…The mixture was dried over phosphorus pentoxide and crystallized from hot anhydrous 2-propanol under an argon atmosphere, m.p. 121 °C (119-122 °C [9] …”

Section: -Hydroxyimidazole Hydrobromide (3)mentioning

confidence: 99%

“…Other syntheses of this compound have been published in the meantime. Oxidation of imidazole gave only very low yields (using peroxyphthalic acid [8] or 3-chloroperoxybenzoic acid [9,10]). A better strategy involved mono-benzylation of 1-hydroxyimidazole-3-oxide, followed by deoxygenation using phosphorus trichloride and hydrogenolytic debenzylation [10].…”

Section: Introductionmentioning

confidence: 99%

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Crystal Structures of 1-Hydroxyimidazole and Its Salts

Laus

Kahlenberg

2012

Crystals

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Abstract:The crystal structures of 1-hydroxyimidazole and four protic salts (chloride, bromide, sulfate, nitrate) thereof were determined. The molecular geometries (bond lengths and angles) of the free base and the salts were compared. Hydrogen bonding patterns were studied, and OH … N, OH … Cl, OH … Br, OH … O, NH … Cl, NH … Br, and NH … O interactions were identified. Hirshfeld surface analysis gave quantitative insight into these interactions.

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Section: Resultsmentioning

confidence: 99%

“…The mixture was dried over phosphorus pentoxide and crystallized from hot anhydrous 2-propanol under an argon atmosphere, m.p. 121 °C (119-122 °C [9] …”

Section: -Hydroxyimidazole Hydrobromide (3)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Crystal Structures of 1-Hydroxyimidazole and Its Salts

Laus

Kahlenberg

2012

Crystals

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“…In a round flask, 1 g (0.12 mmol) of 1 25 was dissolved in 10 mL of anhydrous THF and Ar was flowed during 20 min. Then, a suspension of 476 mg (12 mmol) of 60% NaH in 10 mL of anhydrous THF was added.…”

Section: Methodsmentioning

confidence: 99%

Multidentate ligands from N-hydroxy and N-aminopyrazole

Sanz¹,

Jiménez²,

Claramunt³

et al. 2004

Arkivoc

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The reaction between hexafluorobenzene and the anion of 1-hydroxypyrazole affords a mixture of the products of bis-, tetrakis-and hexakis-substitution. On the other hand the anion of 1-aminopyrazole affords only the product of monosubstitution probably due to the acidity of the remaining NH. Finally, in the case of hexakis(bromomethyl)benzene, its reaction with 1-hydroxypyrazole lead to the hexakis-substituted product. All compounds have been characterized by NMR ( 1 H and 13 C) and mass spectrometry.

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“…[22] By contrast, we prepared NMI-O (8) directly from glyoxal in 48% overall yield (Scheme 1). [22][23][24][25] Our initial studies focused on evaluating the efficiency of catalysts 1-8 (5 mol%) in the acylation of alcohols 9a-9c using hydrocinnamyl chloride (10) as the electrophile and pentamethylpiperidine (PMP) as a non-nucleophilic stoichiometric base in chloroform (0.1 M) at RT for 30 min (Table 1). Table 1.…”

mentioning

confidence: 99%

Amines vs. N‐Oxides as Organocatalysts for Acylation, Sulfonylation and Silylation of Alcohols: 1‐Methylimidazole N‐Oxide as an Efficient Catalyst for Silylation of Tertiary Alcohols

Murray

Spivey

2015

Adv Synth Catal

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A comparison of the relative catalytic efficiencies of Lewisbasic amines vs. N-oxides for the acylation, sulfonylation and silylation of primary, secondary and tertiary alcohols is reported. Whilst the amines are generally superior to the N-oxides for acylation, the N-oxides are superior for sulfonylation and silylation. In particular, 1-methyl-imidazole-N-oxide (NMI-O) is found to be a highly efficient catalyst for sulfonylation and silylation reactions. To the best of our knowledge, NMI-O is the first amine or N-oxide Lewis basic organocatalyst capable of promoting the efficient silylation of tertalcohols in high yield with low catalyst loading under mild reaction conditions.

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Preparation of N-hydroxyazoles by oxidation of azoles

Cited by 43 publications

References 18 publications

Crystal Structures of 1-Hydroxyimidazole and Its Salts

Crystal Structures of 1-Hydroxyimidazole and Its Salts

Multidentate ligands from N-hydroxy and N-aminopyrazole

Amines vs. N‐Oxides as Organocatalysts for Acylation, Sulfonylation and Silylation of Alcohols: 1‐Methylimidazole N‐Oxide as an Efficient Catalyst for Silylation of Tertiary Alcohols

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