Stereoselective <i>O</i>‐Glycosylations by Pyrylium Salt Organocatalysis**

Nielsen, Michael Martin; Holmstrøm, Thomas; Pedersen, Christian

doi:10.1002/anie.202115394

Cited by 24 publications

(10 citation statements)

References 70 publications

(104 reference statements)

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“…Interestingly, PhSiF 3 afforded a cleaner reaction and higher stereoselectivity for a diol substrate (e.g., 180 in Figure e) than a mono-ol one as a glycosyl acceptor, probably because generation of a hexacoordinated intermediate is possible with PhSiF 3 , but not with PhBF 2 . Pedersen and co-workers also reported a stereoselective glycosylation reaction by pyrilium salts based on the same concept of acid–base catalysis . In their reaction, simple pyrilium salts, such as H 3 Pyry ( 182 ) and Me 3 Pyry ( 183 ), promoted stereoselective glycosylation reactions between various glycosyl trichloroacetimidates and glycosyl acceptors including phenols, carbohydrate alcohols, and a serine, although stereoselectivity was generally lower than the previous examples (Figure f).…”

Section: Acid–base Catalysis For Stereoselective Glycosylationmentioning

confidence: 91%

“…Pedersen and co-workers also reported a stereoselective glycosylation reaction by pyrilium salts based on the same concept of acid−base catalysis. 127 In their reaction, simple pyrilium salts, such as H 3 Pyry (182) and Me 3 Pyry (183), promoted stereoselective glycosylation reactions between various glycosyl trichloroacetimidates and glycosyl acceptors including phenols, carbohydrate alcohols, and a serine, although stereoselectivity was generally lower than the previous examples (Figure 25f). Notably, this catalyst accommodates sterically demanding substrates.…”

Section: Acid−base Organocatalystsmentioning

confidence: 97%

“…94 Treatment of D-ribopyranose (125) with 1 equiv of benzoyl methyl phosphate (BMP) in the presence of 10 mol % of La(OTf) 3 and 0.8 equiv of Mg(OTf) 2 in EPPS buffer at room temperature overnight afforded 2-O-benzoylated product 126 with moderate regioselectivity (2-O:3-O:4-O = 6:3:1, Figure 17d). 95 Mg(OTf) 2 formed a complex with methyl phosphate dianion (127) to prevent the lanthanum catalyst from precipitating with the phosphate dianion, realizing the catalytic turnover. They expected the formation of a bisbidentate chelate, such as 128, to make both reactants in close proximity and promote benzoyl transfer from BMP to one of the hydroxy groups.…”

Section: Metal Salts Coordinated By Diolsmentioning

confidence: 99%

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Catalytic Approaches to Chemo- and Site-Selective Transformation of Carbohydrates

Yamatsugu

Kanai

2023

Chem. Rev.

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Carbohydrates are a fundamental unit playing pivotal roles in all the biological processes. It is thus essential to develop methods for synthesizing, functionalizing, and manipulating carbohydrates for further understanding of their functions and the creation of sugar-based functional materials. It is, however, not trivial to develop such methods, since carbohydrates are densely decorated with polar and similarly reactive hydroxy groups in a stereodefined manner. New approaches to chemo-and site-selective transformations of carbohydrates are, therefore, of great significance for revolutionizing sugar chemistry to enable easier access to sugars of interest. This review begins with a brief overview of the innate reactivity of hydroxy groups of carbohydrates. It is followed by discussions about catalytic approaches to enhance, override, or be orthogonal to the innate reactivity for the transformation of carbohydrates. This review avoids making a list of chemo-and site-selective reactions, but rather focuses on summarizing the concept behind each reported transformation. The literature references were sorted into sections based on the underlying ideas of the catalytic approaches, which we hope will help readers have a better sense of the current state of chemistry and develop innovative ideas for the field.

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Section: Acid–base Catalysis For Stereoselective Glycosylationmentioning

confidence: 91%

Section: Acid−base Organocatalystsmentioning

confidence: 97%

Section: Metal Salts Coordinated By Diolsmentioning

confidence: 99%

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Catalytic Approaches to Chemo- and Site-Selective Transformation of Carbohydrates

Yamatsugu

Kanai

2023

Chem. Rev.

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“…Very recently Nielsen et al (2022 ) reported the pyrrylium catalyst (H 3 Pypy) catalyzed β-selective glycosylation of trichloroacetimidate donors. Reaction of reactive carbohydrate or phenol acceptors with α-trichloroacetimidate donor ( 1 ) in the presence of 0.1 equivalent of H 3 Pypy catalyst generated their corresponding β-glycosides ( 3 ) in good yield and stereoselectivity (VII in Scheme 5 ).…”

Section: Techniques For 12- Trans Selective Glycos...mentioning

confidence: 99%

Recent Advances in Stereoselective Chemical O-Glycosylation Reactions

Mukherjee

Ghosh

Hanover

2022

Front. Mol. Biosci.

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Carbohydrates involving glycoconjugates play a pivotal role in many life processes. Better understanding toward glycobiological events including the structure–function relationship of these biomolecules and for diagnostic and therapeutic purposes including tailor-made vaccine development and synthesis of structurally well-defined oligosaccharides (OS) become important. Efficient chemical glycosylation in high yield and stereoselectivity is however challenging and depends on the fine tuning of a protection profile to get matching glycosyl donor–acceptor reactivity along with proper use of other important external factors like catalyst, solvent, temperature, activator, and additive. So far, many glycosylation methods have been reported including several reviews also. In the present review, we will concentrate our discussion on the recent trend on α- and β-selective glycosylation reactions reported during the past decade.

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“…It is noteworthy that a Schreiner thiourea catalyst with a halogen bond donor such as 2-iodoimidazolium salt has been developed to afford 1,2-cis N-glycoside from glycosyl trichloroacetimidate and amide of protected Asn (Li G et al, 2018). Pyrilium salt as an alternative organocatalyst effectively promotes the glycosylation of α and β-glycosyl trichloroacetimidate via S N 2-type inversion to afford β-(1,2cis manno-) and α-(1,2-cis gluco-) glycosides, respectively (Figure 2B2) (Nielsen et al, 2022).…”

Section: Recent Advances On 12-cis Glycosylations By Intermolecular C...mentioning

confidence: 99%

Recent advances in stereoselective 1,2-cis-O-glycosylations

Ishiwata

Tanaka

et al. 2022

Front. Chem.

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For the stereoselective assembly of bioactive glycans with various functions, 1,2-cis-O-glycosylation is one of the most essential issues in synthetic carbohydrate chemistry. The cis-configured O-glycosidic linkages to the substituents at two positions of the non-reducing side residue of the glycosides such as α-glucopyranoside, α-galactopyranoside, β-mannopyranoside, β-arabinofuranoside, and other rather rare glycosides are found in natural glycans, including glycoconjugate (glycoproteins, glycolipids, proteoglycans, and microbial polysaccharides) and glycoside natural products. The way to 1,2-trans isomers is well sophisticated by using the effect of neighboring group participation from the most effective and kinetically favored C-2 substituent such as an acyl group, although high stereoselective synthesis of 1,2-cis glycosides without formation of 1,2-trans isomers is far less straightforward. Although the key factors that control the stereoselectivity of glycosylation are largely understood since chemical glycosylation was considered to be one of the useful methods to obtain glycosidic linkages as the alternative way of isolation from natural sources, strictly controlled formation of these 1,2-cis glycosides is generally difficult. This minireview introduces some of the recent advances in the development of 1,2-cis selective glycosylations, including the quite recent developments in glycosyl donor modification, reaction conditions, and methods for activation of intermolecular glycosylation, including the bimodal glycosylation strategy for 1,2-cis and 1,2-trans glycosides, as well as intramolecular glycosylations, including recent applications of NAP-ether-mediated intramolecular aglycon delivery.

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Stereoselective O‐Glycosylations by Pyrylium Salt Organocatalysis**

Cited by 24 publications

References 70 publications

Catalytic Approaches to Chemo- and Site-Selective Transformation of Carbohydrates

Catalytic Approaches to Chemo- and Site-Selective Transformation of Carbohydrates

Recent Advances in Stereoselective Chemical O-Glycosylation Reactions

Recent advances in stereoselective 1,2-cis-O-glycosylations

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