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Journal ArticleDOI

Reaction of 2,3-unsaturated aryl glycosides with lewis acids : a convenient entry to C-aryl glycosides

19 May 1992-Tetrahedron Letters (Pergamon)-Vol. 33, Iss: 21, pp 3061-3064
Abstract: A facile synthesis of 2′,3′-unsaturated-C-aryl glycosides by BF 3 .Et 2 O mediated ‘O’ to ‘C’ transformation of 2,3-unsaturated aryl glycosides is reported.
Topics: Aryl (56%), Lewis acids and bases (52%)
Citations
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Book ChapterDOI
18 Dec 2001-ChemInform
Abstract: Glycals (or usually their O-substituted derivatives) are readily converted into 2,3-unsaturated glycosyl compounds with O-, C-, N-, S- or otherwise linked substituents at the anomeric position. These products have been found to be useful for a range of synthetic purposes. In particular, the C-glycosidic compounds have served as readily available starting materials for the preparation of useful non-carbohydrate compounds. While these allylic rearrangement processes are usually conducted under the influence of Lewis acid catalysts, adaptations that involve activation of the allylic substituents of the starting glycals as leaving groups under neutral conditions have been developed. General features of the reactions are described as well as applications in synthesis and extensions of the basic processes.

141 citations


Journal ArticleDOI
28 Feb 2018-Chemical Reviews
TL;DR: The aryl C-glycoside structure is, among the plenty of biologically active natural products, one of the distinct motifs embedded, and the synthetic strategies and tactics employed in the total synthesis of this class of natural products.
Abstract: The aryl C-glycoside structure is, among the plenty of biologically active natural products, one of the distinct motifs embedded. Because of the potential bioactivity as well as the synthetic challenges, these structures have attracted considerable interest, and extensive research toward the total synthesis has been performed. This Review focuses on the synthetic strategies and tactics employed in the total synthesis of this class of natural products. The Introduction describes the historical background, structural features, and synthetic problems associated with aryl C-glycoside natural products. Next the Review summarizes the methods for constructing the aryl C-glycoside bonds. Completed total syntheses—and, in some cases, selected examples of incomplete syntheses—of natural aryl C-glycosides are also summarized. Finally described are the strategies for constructing polycyclic structures, which were utilized in the total syntheses.

113 citations


Journal ArticleDOI
TL;DR: This perspective analyzes the various methods used for the activation and [1, 3] rearrangement of vinyl ethers with an emphasis on mechanism and applications to stereoselective synthesis.
Abstract: The relay of stereochemistry of a breaking C–O bond into a forming C–C bond is well-known in the context of [3, 3] sigmatropic shifts; however, this useful strategy is less well-known in other types of molecular rearrangements. Though the first successful example of a [1, 3] O-to-C rearrangement was reported more than 100 years ago, this class of reactions has received less attention than its [3, 3] counterpart. This perspective analyzes the various methods used for the activation and [1, 3] rearrangement of vinyl ethers with an emphasis on mechanism and applications to stereoselective synthesis. We also highlight our own contributions to this area.

62 citations


Journal ArticleDOI
Abstract: Practical and highly stereoselective aryl and allyl C-glycosidation methods using unprotected sugars as glycosyl donors have been developed. Aryl C-glycosidations of several unprotected 2-deoxy sugars with phenol and naphthol derivatives by the combined use of trimethylsilyl trifluoromethanesulfonate (TMSOTf)−AgClO4 or TMSOTf exclusively gave the corresponding unprotected o-hydroxyaryl β-C-glycosides which appear in many biologically attractive aryl C-glycoside antibiotics as the key subunit. On the other hand, allyl C-glycosidations of several unprotected glycals with allyltrimethylsilane by TMSOTf afforded the corresponding unprotected and 2,3-unsaturated allyl α-C-glycosides in high yields which are versatile synthetic intermediates for the syntheses of optically active natural products.

50 citations


Journal ArticleDOI
Abstract: Montmorillonite K10 was found to catalyze, under microwave irradiation, rapid O-glycosidation of 3,4,6-tri-O-acetyl-d-galactal to afford exclusively the alkyl and aryl 2,3-dideoxy-d-threo-hex-2-enopyranosides with very high α-selectivity and without the formation of the 2-deoxy-d-lyxo-hexopyranosides. Under these conditions, 3,4,6-tri-O-acetyl-d-glucal as usual also underwent the Ferrier rearrangement.

45 citations


References
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Book ChapterDOI
TL;DR: This chapter reviews recent advances in the chemistry and biochemistry of C-nucleosides, the literature concerning C-arylglycoside (i.e., nonnitrogen heterocyclic C- nucleoside) antibiotics, and recent significant advances in The most frequently used strategy for C-methine synthesis involves the construction of a heterocyClic aglycone from the C-1 substituent of a functionalized sugar intermediate.
Abstract: Publisher Summary This chapter reviews recent advances in the chemistry and biochemistry of C-nucleosides, the literature concerning C-arylglycoside (i.e., nonnitrogen heterocyclic C-nucleoside) antibiotics, and recent significant advances in the synthesis of C-nucleosides and C-glycosides. It also discusses biological test data and data that are relevant to structure–activity relationships. Modification of readily available natural C-nucleosides is an attractive route to new C-nucleoside analogs and derivatives, because one starting material often possesses much of the desired functionality and chiral properties. The chapter illustrates this approach with examples. The most frequently used strategy for C-nucleoside synthesis involves the construction of a heterocyclic aglycone from the C-1 substituent of a functionalized sugar intermediate.

177 citations


Journal ArticleDOI
Abstract: C-Glycosidation of phenols is achieved by treatment of glycosyl fluoride with phenolic compound under Lewis acidic conditions, which leads to initial O-glycoside formation followed by rearrangement to C-congener. Cp 2 HfCl 2 -AgClO 4 is particularly effective for this conversion.

143 citations





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