Synthesis and conformational analysis of C-glycosylbarbiturates

Martı́nez, Manuel Bueno; Mata, Francisca Zamora; Muñoz‐Ruiz, Angel; Pérez, Juan Manuel Sánchez; Jaime, Carlos

doi:10.1016/0008-6215(90)84265-v

Cited by 17 publications

(7 citation statements)

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“…However, classical methods to access such compounds are quite tedious in most cases because they usually rely on activation of the anomeric position that often requires the protection of the hydroxyl groups. , More attractive strategies for the selective functionalization of the anomeric position rely on the use of the aldehyde moiety from unprotected sugars. Representative examples include the Lubineau reaction with 1,3-diketones, which was used as a key step for the synthesis of L’Oréal’s blockbuster Pro-Xylane, the condensation between aldoses and barbituric acid derivatives or Meldrum’s acid, the Horner–Wadsworth–Emmons reaction between unprotected mono/disaccharides and β-keto-phosphonates, or the recently reported elegant organocatalyzed cascade reactions between unprotected carbohydrates and ketones. − …”

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“…The present chemical approach, depicted in Scheme , is based on the direct condensation of barbituric acid with unprotected sugars 5 , yielding C -glycosyl barbiturates 6 . Despite the efficiency and robustness of this reaction, its synthetic potential, however, remains under-exploited .…”

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“…Based on this strategy, these studies were initiated by examining the direct oxidative cleavage of the C-5 monosubstituted barbiturate core, which has never been tried so far to our knowledge. , d -Glucose 5a , the most common sugar, was selected as a model substrate and condensed with dimethylbarbituric acid . Whereas the in situ reaction of the intermediate sodium barbiturate with sodium hydroxide was found to be inefficient, its reaction with aqueous hydrogen peroxide at 60 °C interestingly led to α-hydroxyamide 7a , a compound that was isolated in 31% yield as a mixture of only two diastereoisomers (Scheme ).…”

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Divergent Entry to C-Glycosides from Unprotected Sugars

et al. 2019

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An efficient, divergent, and straightforward access to novel C-glycosides has been developed, namely, α-hydroxy carboxamide and carboxylic acid derivatives, via a green and scalable process from unprotected carbohydrates. The method involves condensation of 1,3-dimethylbarbituric acid with unprotected sugars followed by subsequent barbiturate oxidative cleavage in the same pot. Further expanding of the chemistry led to the development of efficient entries to diastereoisomerically pure C-glycosyl-α-hydroxy esters or amides through nucleophilic attack on a readily available and versatile key lactone intermediate.

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Divergent Entry to C-Glycosides from Unprotected Sugars

et al. 2019

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“…Upon deprotonation, barbituric acid acts as a strong nucleophile in Knoevenagel condensation reactions, even in water (unlike its close chemical relative, uracil). Perez and co-workers found that, under neutral to basic conditions, and at room temperature or with mild heating, barbituric acid (or its 1,3-dimethyl derivative) readily reacts with various sugars (both pentoses and hexoses) to form barbiturate glycosides. − For the reactions of hexoses and xylose, the β- C -pyranoside was produced exclusively. Arabinose produced the α- C -pyranoside exclusively.…”

Section: Synthesis Of Noncanonical Nucleosides By Divalent Nucleophil...mentioning

confidence: 99%

Prebiotic Syntheses of Noncanonical Nucleosides and Nucleotides

2020

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The origin of nucleotides is a major question in origins-of-life research. Given the central importance of RNA in biology and the influential RNA World hypothesis, a great deal of this research has focused on finding possible prebiotic syntheses of the four canonical nucleotides of coding RNA. However, the use of nucleotides in other roles across the tree of life might be evidence that nucleotides have been used in noncoding roles for even longer than RNA has been used as a genetic polymer. Likewise, it is possible that early life utilized nucleotides other than the extant nucleotides as the monomers of informational polymers. Therefore, finding plausible prebiotic syntheses of potentially ancestral noncanonical nucleotides may be of great importance for understanding the origins and early evolution of life. Experimental investigations into abiotic noncanonical nucleotide synthesis reveal that many noncanonical nucleotides and related glycosides are formed much more easily than the canonical nucleotides. An analysis of the mechanisms by which nucleosides and nucleotides form in the solution phase or in drying−heating reactions from pre-existing sugars and heterocycles suggests that a wide variety of noncanonical nucleotides and related glycosides would have been present on the prebiotic Earth, if any such molecules were present. CONTENTS 1. Introduction 4806 1.1. General Nomenclature and Definitions 4806 1.2. Challenges, Motivations, Opportunities, and Scope 4807 1.3. Defining Two Distinct Non-Enzymatic Glycosylation Reactions 4811 2. Synthesis of Noncanonical Nucleosides by Monovalent Nucleophilic Heterocycles 4812 3. Synthesis of Noncanonical Nucleosides by Divalent Nucleophilic Heterocycles 4813 4. Synthesis of Noncanonical Nucleosides by Concomitant Sugar-Nucleobase Formation 4818 5. Challenges Associated with Phosphate and the Possibility of Earlier Alternatives 4821 6. Discussion 4824 Author Information 4827 Corresponding Author 4827 Authors 4827 Notes 4827 Biographies 4827 Acknowledgments 4828 References 4828

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“…Starting from free D-mannose, reaction of the masked aldehyde function with pyrimidine derivatives [225] or 1,3-dimethylbarbituric acid [226][227][228] followed by heating, directly gave the desired b-C-mannopyranosides (Scheme 75).…”

Section: Intramolecular Reaction Between An Alcohol and An Unsaturatementioning

confidence: 99%