Reactivity of per-O-acetylated 1-thioglycosides and glycosyl sulfones towards chromium(II) complexes in aqueous medium

Synthesis of anomeric sulfonamides and their behaviour under radical-mediated bromination conditions

“…As an alternative route to sulfinates, the reductive cleavage of benzothiazolyl sulfones was proposed; 21 however, practically no change could be observed in the reaction of O-peracetylated b-D-glucopyranosyl 100 benzothiazol-2-yl sulfone 24 with NaBH 4 in THF/MeOH for $one week even at elevated temperature. Sulfinate 13, without being purified, was treated with H 2 NOSO 3 H in water to give the desired sulfonamide 14 after chromatographic purification in 81% yield for the two steps.…”

Ruthenium Catalyzed Stereo/Chemo/Regioselective One-Pot Synthesis of C(2)–C(3) Unsaturated and α-d-Mannopyranosyl Sulfones

“…In addition, the glycosyl sulfones, the higher oxidized form of thioglycosides have been extensively utilized as versatile chiral synthons in assembling various functionalized saccharides, involving (1) chemical glycosylation under a MgBr 2 ·Et 2 O reagent system; (2) Sm­(OTf) 3 catalyzed glycosylation; (3) C-glycosylation via lithiated anion coupling reaction with a carbonyl group; ( 4 ) Ramberg-Backlund and hydrogenation reaction sequence for C-linked glycoconjugates; ( 5 ) stereocontrolled C -glycosylation via glycosyl samarium intermediates; and (6) Umpolung approach to glycals via an anomeric radical and sugar-chromium­(III) complex …”

Synthesis of Pyranoid and Furanoid Glycals from Glycosyl Sulfoxides by Treatment with Organolithium Reagents

“…[22] In spite of the ready availability of glycosyl halides, their rather sensitive natures have led to the consideration of the more stable 1-thio-and 1-sulfonylglycosyl derivatives (e.g., 3, Scheme 1b) as glycal precursors. Compounds 3 are thus conveniently transformed into glycals when treated with lithium naphthalide, [23] chromium(II) complexes in aqueous medium, [24] or SmI 2 . [14,25] In the last case, electron transfer to the glycosyl phenylsulfone to generate a 1-glycosyl radical has been proposed; a (glycosyl)samarium deriva-tive would then be formed, [14,25] with subsequent β-acetate elimination resulting in the formation of the expected glycal.…”