Topic
Glycal
About: Glycal is a research topic. Over the lifetime, 897 publications have been published within this topic receiving 17422 citations.
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TL;DR: Exo-Glycals are unsaturated sugars that have a double bond attached to the anomeric center outside the sugar ring as mentioned in this paper, which is useful for the synthesis of C-glycosides and compounds containing quaternary carbons, provided that the olefin can be properly reduced or functionalized.
Abstract: It is well known that carbohydrates play an indispensable role in a variety of essential biological activities, such as cell-cell adhesion, bacteria and virus infections, and tumor metastasis. Among an increasing number of sugars and sugar mimetics that have been designed and synthesized for the purpose of drug discovery, C-glycosides are considered to be one of the best choices on account of their stability and resemblance as they differ from normal glycosides only in glycosidic linkages. exo-Glycals are unsaturated sugars that have a double bond attached to the anomeric center outside the sugar ring. These carbohydrate molecules are useful for the synthesis of C-glycosides and compounds containing quaternary carbons, provided that the olefin can be properly reduced or functionalized. This review places special emphasis on two aspects of exo-glycals including general methods of preparation and synthetic applications for making biologically important molecules. The first half discusses the methods of addition/elimination and Ramburg-Backlund rearrangement that offer many beneficial features including a wide range of double bond substitutions, limited reaction steps, easy operation and good overall yields. The rest of the article demonstrates a number of synthetic studies using exoglycals as the starting materials. The target molecules can be categorized into three groups, namely C-glycosides, enzyme inhibitors and bioactive natural products.
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28 Nov 2012
TL;DR: In this paper, the authors provided an addition method of glycal and alcohol compounds, and the addition method comprises the following steps of: a, mixing glycal, alcohol compounds and triphenylphosphine hydrobromide in a first organic solvent for carrying out an addition reaction; b, regulating the pH value of a reaction solution obtained in the step a to be neutral; and c, cleaning a neutral reaction solution by using a second organic solvent to obtain a reaction product.
Abstract: The invention provides an addition method of glycal and alcohol compounds, and the addition method comprises the following steps of: a, mixing glycal, alcohol compounds and triphenylphosphine hydrobromide in a first organic solvent for carrying out an addition reaction; b, regulating the pH value of a reaction solution obtained in the step a to be neutral; and c, cleaning a neutral reaction solution obtained in the step b by using a second organic solvent to obtain a reaction product, wherein the second organic solvent is liquid alkane with a carbon atom number of less than or equal to 10. According to the method provided by the invention, the triphenylphosphine hydrobromide is used as a catalyst, and is relatively smaller in acidity, so that the addition reaction of glycal is higher in reaction efficiency; and glycal can fully react, so that the addition product of glycal is increased. The second organic solvent adopted by the invention can be used for dissolving the catalyst without dissolving the product, so that the catalyst is removed from the reaction solution by adopting the second organic solvent, and the purity of the addition production of glycal is improved.
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TL;DR: In this paper, the formation of sialic acid glycosides with a trifluoromethanesulfonic anhydride is reported, which can be used for coupling to a wide range of primary, secondary, and tertiary acceptors.
Abstract: The formation of sialic acid glycosides with a thiosialic acid derivative, diphenyl sulfoxide, and trifluoromethanesulfonic anhydride is reported. With an excess of diphenyl sulfoxide, glycal formation can be completely suppressed and excellent yields are obtained for coupling to a wide range of primary, secondary, and tertiary acceptors.
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TL;DR: In this paper, the glycal 5 is converted to intermediates which undergo, under mild conditions, thermal aza-Claisen rearrangements, leading to the amides 7 and 8 and the 2 pyrimidone 9, all potential precursors to 2′,3′-dideoxynucleosides.
Abstract: The glycal 5 is converted to intermediates which undergo, under mild conditions, thermal aza-Claisen rearrangements, leading to the amides 7 and 8 and the 2-pyrimidone 9 , all potential precursors to 2′,3′-dideoxynucleosides.
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TL;DR: In this article, a Balkyl Suzuki-Miyaura cross coupling approach was proposed to convert glycals to C1-alkyl glycals and C 1-acylglycals that are versatile synthetic intermediates.
Abstract: A B-alkyl Suzuki–Miyaura cross coupling approach provides a flexible, efficient means to convert glycals to C1-alkylglycals and C1-acylglycals that are versatile synthetic intermediates. This approach uses readily available glycal starting materials and overcomes major limitations associated with direct alkylation or acylation of glycals. Further, a commonly observed side reaction involving reduction of the halide coupling partner is suppressed by preincubation of the borane coupling partner with aqueous base, providing new mechanistic insights into the side reaction.