Acid-catalyzed reactions of alloxan with compounds containing an activated alkyl group

Alexeenko, Danil V.; Ukhin, L. Yu.; Suponitskii, K. Yu.; Шепеленко, Е. Н.; Belousova, L. V.; Бородкин, Г. С.

doi:10.1134/s1070428016070186

Cited by 1 publication

(2 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is likely due to the fact that alloxan has been shown to rapidly break down to the five-membered isomer alloxanic acid in aqueous solutions with pH values greater than ∼3 , (see Supporting Note 1 for an explanation of this effect within our recrystallization experiments). In addition, acidic protonation of one of the gem-diol alcohol moieties followed by loss of water is thought to produce the active hydronium ionic species susceptible to nucleophilic attack in these types of syntheses . The 1 H and 13 C{ 1 H} NMR results of alloxan monohydrate in acetic acid- d 4 are presented in Figure S5, and the results are similar to that seen for D 2 O, further reaffirming that only the gem-diol version of alloxan is detectable in protic solutions.…”

Section: Resultssupporting

confidence: 60%

“…In addition, acidic protonation of one of the gem-diol alcohol moieties followed by loss of water is thought to produce the active hydronium ionic species susceptible to nucleophilic attack in these types of syntheses. 30 The 1 H and 13 C{ 1 H} NMR results of alloxan monohydrate in acetic acid-d 4 are presented in Figure S5, and the results are similar to that seen for D 2 O, further reaffirming that only the gem-diol version of alloxan is detectable in protic solutions. Thus, it is clear that in protic solvents, H 2 O addition of alloxan monohydrate at the C5 carbon occurs to form the gemdiol 3 exclusively.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Structure and Reactivity of Alloxan Monohydrate in the Liquid Phase

et al. 2021

View full text Add to dashboard Cite

Alloxan is an important toxic glucose analogue used to induce diabetes in lab test animals. Once regarded as a "problem structure," the condensed-phase structure of anhydrous alloxan has largely been settled, but literature inconsistencies remain for the structure of the typically employed reagent alloxan monohydrate. Due to the criticality of structure−function relationships, we have used 1 H/ 13 C{ 1 H} NMR, IR spectroscopy, as well as quantum mechanical (QM) calculations to probe the liquid-phase structure and reactivity of alloxan monohydrate. In protic solvents (D 2 O and acetic acid-d 4 ), hydration at the C5 carbonyl of alloxan monohydrate occurs quantitatively to form the C5 gem-diol (5,5′-dihydroxybarbituric acid). In the aprotic solvent dimethyl sulfoxide (DMSO)-d 6 , there exists a mixture of the C5 gem-diol and planar tetraketo form of alloxan monohydrate. QM calculations explain the solvent-dependent hydration reactivity, where a solvent-assisted H-atom transfer mechanism lowers the activation energy of water addition at the C5 carbonyl by ∼16 or 27 kcal/ mol in water or acetic acid, respectively, compared to the unassisted hydration reaction. Prompt recrystallization of alloxan monohydrate from boiling water does not alter the structure of the reagent. These findings probe the exact structure of alloxan monohydrate to guide future research efforts in biological sciences and in organic synthesis.

show abstract

Section: Resultssupporting

confidence: 60%

Section: Resultsmentioning

confidence: 99%