Thioglycosides

Abstract

Thioglycosides are not very common in nature, only a few simple alkyl and aryl thioglycosides have been found as constituents of antibiotics from Streptomyces species [ 1-31. Although not really thioglycosides, glucosinolates with an anomeric sulfur are also well-known natural compounds [4, 51. In spite of their low natural abundance, thioglycosides and their chemistry have for a long time been a field of interest for many researchers, the first thioglycoside was synthesized in 1909 [6], and their basic chemistry was early reviewed [4, 71. But it is only recently that their excellent glycosyl donor qualities have been recognized. In the beginning of the seventies the first successful synthesis of a disaccharide was performed [S], but it was not until the middle of the eighties that enough efficient promoters were discovered to make glycosylation with thioglycoside donors into a general and accepted method. Since then and in a very short time-span, thioglycosides have become one of the most used type of donors, especially in glycosylations with oligosaccharide donors (block synthesis). There are already some reviews on the subject [9-121, and in the most recent complete list of published glycosylations during one year (1994) [ 131, thioglycosides were used as donors in about 20% of all reported glycosylations and in 35% of all couplings using oligosaccharide donors, competing well with the long established halide donors and the trichloroacetimidate method.The strength of thioglycosides as glycosyl donors is their easy synthesis (Section 4.2) combined with their stability, withstanding most reaction conditions used in e.g. protecting group manipulations and glycosylations, and at the same time their effective acth ation using chemoselective thiophilic promoters (Sections 4.3.2 and 4.4.1) and also easy transformation into other types of glycosyl donors (Section 4.3.1). Hence, they are perfectly fitted to be used in block synthesis of oligosaccharides, where stable oligosaccharide donors are a prerequisite. Their stability also makes them very apt in synthetic schemes where a number of chemical modifications are performed just prior to the glycosylations, as, e.g., in various types of Carbohydrates in Chemistry and Biology

Copper(II) Triflate: A Versatile Catalyst for the One‐Pot Preparation of Orthogonally Protected Glycosides

“…[18] To that end, a series of synthetic thiophenyl glycosides, including examples containing allyl protecting groups and a series of common N-protecting groups (NHTroc, NPhth, NHAc) (compounds 3-8) were prepared. In addition, a series of O-glycosides bearing either a 1-O-alkyl azide chain, a 1-O-alkyl halide chain or an acid labile 1,2-ortho ester (compounds 9-11), were prepared.…”

Improved Synthesis of 1‐Benzenesulfinyl Piperidine and Analogs for the Activation of Thioglycosides in Conjunction with Trifluoromethanesulfonic Anhydride*

“…[24][25][26][27] We anticipate that between BSP, its analogs introduced here, the recent modification of Wong (23), [28] and diphenyl sulfoxide, a reagent will be found to activate almost all classes of thioglycoside, in conjunction with trifluoromethanesulfonic anhydride, under milder conditions than have hitherto been possible. [29][30][31] 2. .…”

Synthesis of mucin-type O-glycan probes as aminopropyl glycosides

“…In this report, we employed the difference in reactivity of trichloroacetimidates and thioglycoside donors. In general, trichloroacetimidates are activated by strong Lewis acids such as TMSOTf [28], while the more stable thioglycosides require the presence of a more electrophilic species such as N- iodosuccinimide/TMSOTf combinations [29–30]. To that end, thioglycoside building block 23 bearing a free OH at C-3 was synthesized following reported procedures [16] and subjected to a chemo- and stereoselective glycosylation reaction with peracetylated trichloroacetimidate donor 13 in the presence of catalytic TMSOTf.…”