Anomeric modification of carbohydrates using the Mitsunobu reaction

• Julia Hain,
• Patrick Rollin,
• Werner Klaffke and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1619–1636, doi:10.3762/bjoc.14.138

• achieve good results in the Mitsunobu procedure. We have reviewed on the one hand the literature on anomeric esterification, including glycosyl phosphates, and on the other hand glycoside synthesis, including S- and N-glycosides. The mechanistic details of the Mitsunobu reaction are discussed as well as

• circumstances. Keywords: anomeric stereoselectivity; carbohydrates; glycoside synthesis; Mitsunobu reaction; Introduction Fifty years ago, Oyo Mitsunobu reported a preparation of esters from alcohols and carboxylic acids supported by two auxiliary reagents, diethyl azodicarboxylate (DEAD) and

• outcome of the reaction towards β-configured products [53]. In this case, phenolic chromium tricarbonyl complexes of weaker acids such as p-cresol were employed to improve the yield. The challenge of glycoside synthesis using sugars devoid of a C-2 participating group is also highlighted by a total

Enzymatic synthesis of glycosides: from natural O- and N-glycosides to rare C- and S-glycosides

• Jihen Ati,
• Pierre Lafite and
• Richard Daniellou

Beilstein J. Org. Chem. 2017, 13, 1857–1865, doi:10.3762/bjoc.13.180

• methodology of enzymatic synthesis of these particular (but mostly unstable) carbohydrate derivatives. These mutants were also developed as powerful biocatalysts for the synthesis of complex O-glycosides through the concepts of glycosynthases or thioglycosynthases [61]. S-Glycoside synthesis In retaining GHs

• thiofuranosides [76]. C-Glycosides synthesis There is no example of C-glycoside synthesis promoted by GHs reported in the literature so far, although as depicted by the mechanism, this kind of biocatalysed reaction can be envisioned. Conclusion To conclude, the enzymatic mechanisms that rule the activities of GTs

A selective and mild glycosylation method of natural phenolic alcohols

• Mária Mastihubová and
• Monika Poláková

Beilstein J. Org. Chem. 2016, 12, 524–530, doi:10.3762/bjoc.12.51

• to the stereoselective glycoside synthesis. The final products were obtained by conventional Zemplén deacetylation. Keywords: diastereoselectivity; p-hydroxyphenylalkyl glycosides; mild promoters; natural products; 1,2-trans-glycosylation; Introduction Arylalkyl (substituted benzyl, phenethyl and

• new promoter in the stereoselective 1,2-trans-glycoside synthesis (Table 1, entries 4, 9, 13, 17, 19 and 25). The selection of methods C and D was based on the common knowledge that iodine, either alone or in combination with other promoters such as salts of various metals (other than the traditional

• Koenigs–Knorr heavy metals), serves as an effective activator of disarmed glycosyl halides in the 1,2-trans-glycoside synthesis [35][36][37][38]. Despite the fact that the precise mechanism is not clear, it is assumed that the reaction of the glycosyl bromide promoted by iodine (through the formation of

Synthesis in the glycosciences

• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2010, 6, No. 16, doi:10.3762/bjoc.6.16

• . Since the isolation of those complex glycans which are active in cellular communication is problematic, oligosaccharide synthesis is an important area of research. Moreover, what Professor Hans Paulsen, one of the greatest exponents of glycoside synthesis, observed in 1982 [2] still holds true today

• syntheses”. It is therefore not surprising that the majority of contributions collected in this Thematic Series deal with methods, both chemical and enzymatic, for oligosaccharide synthesis. One approach to deal with the problem of glycoside synthesis is the preparation of so-called glycomimetics. This is a