Convenient syntheses of 1,2-trans selenoglycosides using isoselenuronium salts as glycosylselenenyl transfer reagents

Exploring the Syntheses of Novel Glycomimetics. Carbohydrate Derivatives with Se‐S‐ or Se‐Se‐ Glycosidic Linkages

“…Glycosyl selenols, unlike glycosyl thiols, are much more sensitive toward oxidation and, therefore, cannot be isolated in practice per se . Glycosylisoselenuronium salts, on the other hand, can function as masked selenols and serve as convenient glycosylselenenyl transfer reagents in reactions resulting in the formation of alkyl‐ and aryl selenoglycosides (Glyc‐Se−R) or diglycosyl selenides (Glyc1‐Se‐Glyc2) as we have recently reported . We have envisioned that these reagents might react with thiols or selenol precursors resulting in the formation of glycosyl derivatives with Se‐S or Se‐Se ‐ glycosidic bonds.…”

“…triethylamine (TEA) at room temperature. Thus, glycosylselenenylsulfides 6, 7, 8 and 9 were obtained from 2,3,4,6‐tetra‐ O ‐acetyl‐β‐D‐glucopyranosyl iso selenuronium bromide 4 or 2‐acetamido‐2‐deoxy‐3,4,6,–tri‐ O‐ acetyl‐β‐D‐glucopyranosyl iso selenuronium chloride 5 in poor to moderate yields because of side reactions (see below).…”

Sweet Selenium: Synthesis and Properties of Selenium-Containing Sugars and Derivatives

“…A recent evolution of the path C methodology was reported by Kumar et al, who prepared selenonucleosides starting from commercially available, activated sugars ( 69 , Scheme 11 ) and selenourea. The resulting isoselenuronium salts 70 were isolated and then functionalized with various alkyl, aryl, and acyl moieties or monosaccharides [ 77 ]. The authors prepared more than 30 compounds, all deprotected under basic conditions (compounds 72 ).…”

Atom Efficient Preparation of Zinc Selenates for the Synthesis of Selenol Esters under “On Water” Conditions

“…As a consequence of the increasing demand for selenol esters, the number of methods to prepare this class of compounds has been increased along the years [1,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43] Among the strategies to prepare selenol esters there are the reactions of nucleophilic selenium reagents with an acyl group source, such as N -acyl benzotriazoles [17,18] activated carboxylic acids (using DCC [3] or PBu 3 [4,5,19,20]), enol esters [21], anhydrides [22,23,24], esters [25], carbon monoxide [26,27], aldehydes [28,29] or acyl chlorides [2,7,30,31,32,33,34,35,36,37,38,39,40,41,42,43]. Other approaches to selenol esters involve the alkylation of selenocarboxylate anions with alkyl h...…”

“…The acyl substitution of acyl chlorides is by far the most explored method to access selenol esters, mainly because of its versatility, since the diversity of acyl chlorides that can be prepared is practically endless. The pivotal step in this reaction is the generation of the nucleophilic selenium species and a range of reagents have been used for this purpose, including Se°/ArMgBr [2], (NH 2 ) 2 C=Se/Et 3 N [30], Se°/NaBH 4 [6], InI/(PhSe) 2 [31,39,40], Se°/LiAlH 4 [32,37], (RSe) 2 /Zn/AlCl 3 [33], Ph(NH 2 )C=Se [34], (Bu 3 Sn) 2 /(PhSe) 2 /hv [35,36], Se°/R 2 C=CZrCp 2 Cl [38], (RSe) 2 /Zn°/[bmim]PF 6 [41], (PhSe) 2 /Hg°/dioxane [42] and (PhSe) 2 /SnCl 2 /CuBr 2 /[bmim]BF 4 [43]. Despite these reaction systems afforded a range of selenol esters, they suffer from one or more of the following drawbacks: use of VOCs as solvent, strong bases, strong and moisture sensible reducing agents, expensive reagents and low atom-economy.…”