ChemInform Abstract: Saturated and Unsaturated Thioglycoside Syntheses.

Abstract

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Transition‐Metal‐Mediated Glycosylation with Thioglycosides

“…Other important compounds for remote activation are S ‐thiazolinyl (STaz) derivatives that were introduced by Descotes and co‐workers as glycosyl donors that can be activated with HgNO 3 [89] . Further investigation into the glycosylation protocol toward disaccharide and oligosaccharide synthesis was reported by Demchenko et al.…”

“…Other important compounds for remote activation are Sthiazolinyl (STaz) derivatives that were introduced by Descotes and co-workers as glycosyl donors that can be activated with HgNO 3 . [89] Further investigation into the glycosylation protocol toward disaccharide and oligosaccharide synthesis was reported by Demchenko et al Activators such as AgOTf, MeOTf, NIS/ TfOH, benzyl bromide, methyl iodide, AgBF 4 and Cu(OTf) 2 have been found to be suitable for efficient STaz activation for glycosylation and glycan synthesis. [41a] For example, chemoselective activation of armed STaz donor 69 over disarmed acceptor 70 in the presence of Cu(OTf) 2 afforded product 71 predominantly as the α-anomer.…”

Glycosyl thioimidates as versatile building blocks for organic synthesis

“…(Scheme 11) [74]. Ferrieres and Plusquellec described the synthesis of peracetylated thiazolinyl galactofuranosides from β-D-galactofuranose pentaacetate in the presence of BF 3 · Et 2 O in 53% yield [52, 53].…”

“…Formation of by-products, N -linked “Taz” and 1,2-anhydro derivatives, are probably due to ambient reactivity of HSTaz and its relatively high basicity. Nevertheless, the STaz glycosides were obtained from anomeric chlorides 43 [27], thioglycosides (e.g., 45 ) [31], 1,2-anhydro sugars 14 [74], or 1,2-orthoesters 44 (Scheme 11) [33]. The formation of 1,2- trans STaz glycosides were found in complete stereoselectivity.…”

“…Early studies by Descotes and co-workers involved the displacement of the STaz functionality of peracetylated derivatives of the D-gluco series using MeOH in the presence of HgNO 3 [74]. Further investigation into the glycosylation protocol toward disaccharide and oligosaccharide synthesis was reported by Demchenko et al .…”