Unprecedented β-manno type thiodisaccharides with a C-glycosylic function by photoinitiated hydrothiolation of 1-C-substituted glycals

Lázár, László; Juhász, László; Batta, Gyula; Borbás, Anikó; Somsák, László

doi:10.1039/c6nj03751h

Cited by 22 publications

(18 citation statements)

References 36 publications

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“…The photoinduced thiol‐ene additions of unsubstituted and 1‐substituted glycals enabled regio‐ and stereoselective synthesis of 2‐thio‐linked saccharide mimetics (Scheme and Scheme ) …”

Section: Photoinduced Hydrothiolation Of Glycals and 1‐substituted Glmentioning

confidence: 99%

“…Somsák's group reported that the free‐radical hydrothiolation of amide‐, methoxycarbonyl‐ and cyano‐substituted glycal derivatives (e.g. 88 – 91 ) took place with full regio‐ and stereoselectivity due to the preferential axial attack of the thiyl radical to the less substituted C2 position of the pyranose ring and the preferred axial attack on the C1 radical in the hydrogen abstraction step (Scheme ) …”

Section: Photoinduced Hydrothiolation Of Glycals and 1‐substituted Glmentioning

confidence: 99%

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Photoinitiated Thiol‐ene Reactions of Enoses: A Powerful Tool for Stereoselective Synthesis of Glycomimetics with Challenging Glycosidic Linkages

Borbás

2020

Chemistry A European J

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Thioglycosides and C-glycosidesr epresent pharmacologically useful classes of glycomimetics that possess ah igh degree of biological stability. One emerging tool for the stereoselective synthesis of thioglycosides is the photoinitiateda ddition of thiols to unsaturated sugars. Moreover,t hiyl radical-mediated reactions of exo-glycals and 1-substituted endo-glycalso ffer facile routes to b-Cglycosidic structures. This Concepta rticle summarizes the thiol-ene coupling strategies developed recently by our group andS omsµk'sg roup for the synthesis of several kinds of glycomimetics which are difficult to synthesize by conventionalm ethods. One unusual characteristico ft he thiol-ene reactions of endo-glycals is that heating inhibits, whereas cooling promotes the reaction. This unique temperature dependence as well as the effects of the enose structures and thiol configurations on the efficacya nd stereoselectivityo ft he reactions are also discussed.[a] Prof.

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Section: Photoinduced Hydrothiolation Of Glycals and 1‐substituted Glmentioning

confidence: 99%

Section: Photoinduced Hydrothiolation Of Glycals and 1‐substituted Glmentioning

confidence: 99%

Photoinitiated Thiol‐ene Reactions of Enoses: A Powerful Tool for Stereoselective Synthesis of Glycomimetics with Challenging Glycosidic Linkages

Borbás

2020

Chemistry A European J

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“…The radical-mediated addition of thiols to non-activated double bonds is widely used in organic syntheses, material sciences, and glycochemistry as a robust ligation tool [23][24][25][26]. Recent results have demonstrated that applying unsaturated sugars as the alkene partners in the thiol-ene coupling reactions offers a rapid route to a broad range of thio-linked glycomimetics, including 1,2-cis α-S-glycosides [27][28][29][30][31], 2-thio-β-mannosides [32] as well as C-S-bonded carbohydrate mimetics, wherein the CH 2 -S linkage is attached to the C1 or the C5 position of the pyranosyl ring [33][34][35] (Scheme 1B). Dondoni and co-workers reported that, while photoinduced hydrothiolation of 5-exomethylene pyranoside 1 with 1-thioaldose 2a furnished the corresponding S-linked disaccharide 3 with complete regio-and stereoselectivity, addition reaction to galactopyranosyl 5-exomethylene 4 occured with only moderate stereoselectivity, yielding a 3:1 mixture of 5a and 5b (Scheme 1(B1)) [33].…”

Section: Resultsmentioning

confidence: 99%

Stereoselective Synthesis of Carbon-Sulfur-Bridged Glycomimetics by Photoinitiated Thiol-Ene Coupling Reactions

Csávás

Eszenyi

Mező

et al. 2020

IJMS

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Oligosaccharides and glycoconjugates are abundant in all living organisms, taking part in a multitude of biological processes. The application of natural O-glycosides in biological studies and drug development is limited by their sensitivity to enzymatic hydrolysis. This issue made it necessary to design hydrolytically stable carbohydrate mimetics, where sulfur, carbon, or longer interglycosidic connections comprising two or three atoms replace the glycosidic oxygen. However, the formation of the interglycosidic linkages between the sugar residues in high diastereoslectivity poses a major challenge. Here, we report on stereoselective synthesis of carbon-sulfur-bridged disaccharide mimetics by the free radical addition of carbohydrate thiols onto the exo-cyclic double bond of unsaturated sugars. A systematic study on UV-light initiated radical mediated hydrothiolation reactions of enoses bearing an exocyclic double bond at C1, C2, C3, C4, C5, and C6 positions of the pyranosyl ring with various sugar thiols was performed. The effect of temperature and structural variations of the alkenes and thiols on the efficacy and stereoselectivity of the reactions was systematically studied and optimized. The reactions proceeded with high efficacy and, in most cases, with complete diastereoselectivity producing a broad array of disaccharide mimetics coupling through an equatorially oriented methylensulfide bridge.

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“…Phosphorus-centered radicals have been less intensively studied in carbohydrate chemistry, but addition products can be used for further transformations. On the other hand, the addition of sulfur-centered radicals to glycals has become very attractive for the synthesis of thio-disaccharides [68][69][70][71][72]. Photochemical initiators based on ketones have been developed for The addition of thiols by radical chain reactions to the 2-position of glycals has only one disadvantage: that the 1-position is reduced under the reaction conditions.…”

Section: Summary and Perspectivesmentioning

confidence: 99%

Addition of Heteroatom Radicals to endo-Glycals †

Linker

2020

Chemistry

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Radical reactions have found many applications in carbohydrate chemistry, especially in the construction of carbon–carbon bonds. The formation of carbon–heteroatom bonds has been less intensively studied. This mini-review will summarize the efforts to add heteroatom radicals to unsaturated carbohydrates like endo-glycals. Starting from early examples, developed more than 50 years ago, the importance of such reactions for carbohydrate chemistry and recent applications will be discussed. After a short introduction, the mini-review is divided in sub-chapters according to the heteroatoms halogen, nitrogen, phosphorus, and sulfur. The mechanisms of radical generation by chemical or photochemical processes and the subsequent reactions of the radicals at the 1-position will be discussed. This mini-review cannot cover all aspects of heteroatom-centered radicals in carbohydrate chemistry, but should provide an overview of the various strategies and future perspectives.

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Unprecedented β-manno type thiodisaccharides with a C-glycosylic function by photoinitiated hydrothiolation of 1-C-substituted glycals

Abstract: Unique thiodisaccharides of β-manno type featuring C-glycosylic structure with an anomeric functional group for further elaboration were obtained by radical-mediated hydrothiolation of 1-C-acceptor-substituted glycals.

Cited by 22 publications

References 36 publications

Photoinitiated Thiol‐ene Reactions of Enoses: A Powerful Tool for Stereoselective Synthesis of Glycomimetics with Challenging Glycosidic Linkages

Photoinitiated Thiol‐ene Reactions of Enoses: A Powerful Tool for Stereoselective Synthesis of Glycomimetics with Challenging Glycosidic Linkages

Stereoselective Synthesis of Carbon-Sulfur-Bridged Glycomimetics by Photoinitiated Thiol-Ene Coupling Reactions

Addition of Heteroatom Radicals to endo-Glycals †

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