Radical halogenation-mediated latent–active glycosylations of allyl glycosides

Pal, Rita; Das, Anupama; Jayaraman, Narayanaswamy

doi:10.1039/c7cc07332a

Cited by 8 publications

(4 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Allylic halogenation under photochemical condition was developed by Diaz and co‐workers as a method to deprotect the anomeric allyl moiety of a sugar [72] . Realizing that radical halogenation is a facile reaction, [73] efforts were undertaken to explore the allylic halide ( I ) as a glycosyl donor, promoted by a suitable catalyst. For this purpose, the sugar allylic halides were prepared first by radical halogenation of allyl glycosides (Figure 5).…”

Section: Exocyclic Unsaturation As a Tool For Glycosylationsmentioning

confidence: 99%

“…Further studies showed that a halophilic reagent, such as, AgOTf, as a promoter of the allylic halide II mediated the glycosylation of acceptor alcohols ( III ), leading to the formation of the glycoside ( IV ). Reiteration of allylic halogenation to intermediate V and glycosylation with III afforded VI [73] …”

Section: Exocyclic Unsaturation As a Tool For Glycosylationsmentioning

confidence: 99%

See 1 more Smart Citation

Display of Rich Reactivities of Endo‐ and Exocyclic Unsaturated Sugars that Parallel the Native Sugars

Jayaraman

2021

The Chemical Record

Self Cite

View full text Add to dashboard Cite

Unsaturated monosaccharides expand the scope of reactivities in a sugar, directly leading to the development of newer methodologies, molecular structures and functional entities. The unsaturation as a reactive moiety can either be within the molecule, namely, endocyclic, or as a pendant moiety around the molecule, namely, exocyclic. One carbon homologations aided by reactions at the unsaturated moiety expand the molecular structures in both endo‐ and exocyclic sugars and lead to structures that are largely hitherto unknown. Molecular shifts and rearrangements permit interchanging the reactivities from one carbon to the other in unsaturated sugars. Activations of exocyclic unsaturated sugars also find newer possibilities to reactions central to the sugar chemistry, namely, the glycosylations. The personal reflections result from a couple of decades of explorations that traverse through the unsaturated sugars from different vantage points.

show abstract

Section: Exocyclic Unsaturation As a Tool For Glycosylationsmentioning

confidence: 99%

Section: Exocyclic Unsaturation As a Tool For Glycosylationsmentioning

confidence: 99%

Display of Rich Reactivities of Endo‐ and Exocyclic Unsaturated Sugars that Parallel the Native Sugars

Jayaraman

2021

The Chemical Record

Self Cite

View full text Add to dashboard Cite

show abstract

“…A newer allylic glycoside activation was developed recently in our research group [43]. The newly developed synthetic method combines radical-mediated activation of an allyl glycoside to an allyl halide, which upon reaction with a glycosyl and aglycosyl acceptor in the presence of an acid promoter leads to a glycoside product.…”

Section: (Ii) Allylic Halide Activation Of Allyl Glycosidesmentioning

confidence: 99%

“…Fig. 4: A scheme of latent-active glycosylation involving an allyl glycoside, initiated by a radical-mediated allylic halogenations [43]. A change of the protecting group from O-acetyl to O-benzoyl on the donor moiety increased the yield of the glycosylation product.…”

Section: (Latent)mentioning

confidence: 99%

One-pot oligosaccharide synthesis: latent-active method of glycosylations and radical halogenation activation of allyl glycosides

Pal

Das

Jayaraman

2019

Pure and Applied Chemistry

Self Cite

View full text Add to dashboard Cite

Chemical glycosylations occupy a central importance to synthesize tailor-made oligo- and polysaccharides of functional importance. Generation of the oxocarbenium ion or the glycosyl cation is the method of choice in order to form the glycosidic bond interconnecting a glycosyl moiety with a glycosyl/aglycosyl moiety. A number of elegant methods have been devised that allow the glycosyl cation formation in a fairly stream-lined manner to a large extent. The latent-active method provides a powerful approach in the protecting group controlled glycosylations. In this context, allyl glycosides have been developed to meet the requirement of latent-active reactivities under appropriate glycosylation conditions. Radical halogenation provides a newer route of activation of allyl glycosides to an activated allylic glycoside. Such an allylic halide activation subjects the glycoside reactive under acid catalysis, leading to the conversion to a glycosyl cation and subsequent glycosylation with a number of acceptors. The complete anomeric selectivity favoring the 1,2-trans-anomeric glycosides points to the possibility of a preferred conformation of the glycosyl cation. This article discusses about advancements in the selectivity of glycosylations, followed by delineating the allylic halogenation of allyl glycoside as a glycosylation method and demonstrates synthesis of a repertoire of di- and trisaccharides, including xylosides, with varied protecting groups.

show abstract

Aglycon reactivity as a guiding principle in latent-active approach to chemical glycosylations

Das

Jayaraman

2021

Carbohydrate Research

View full text Add to dashboard Cite

Radical halogenation-mediated latent–active glycosylations of allyl glycosides

Cited by 8 publications

References 31 publications

Display of Rich Reactivities of Endo‐ and Exocyclic Unsaturated Sugars that Parallel the Native Sugars

Display of Rich Reactivities of Endo‐ and Exocyclic Unsaturated Sugars that Parallel the Native Sugars

One-pot oligosaccharide synthesis: latent-active method of glycosylations and radical halogenation activation of allyl glycosides

Aglycon reactivity as a guiding principle in latent-active approach to chemical glycosylations

Contact Info

Product

Resources

About