Thioglycuronides:  Synthesis and Application in the Assembly of Acidic Oligosaccharides

Abstract

[reaction: see text] Partially protected thioglycuronic acids are prepared efficiently by chemo- and regioselective oxidation of the corresponding thioglycosides using the TEMPO/BAIB reagent combination. After esterification, the thioglycuronic acids proved to be useful as both donor and acceptor in sulfonium-mediated condensations toward acidic di- and trisaccharides.

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

“…Mp: 33-34 °C, 1 H NMR δ: 7.66 (m, 2H), δ 7.49 (m, 3H), δ 3.33 (m, 2H), δ 3.00 (m, 2H), δ 1.83 (m, 4H). 13 C NMR δ: 130.6, 128.9, 125.9, 46.2, 26.1.…”

“…[1] BSP met these criteria admirably and activates most thioglycosides for coupling in a matter of minutes at −60 °C as demonstrated in a series of subsequent synthetic endeavors from this [3][4][5][6][7] and other laboratories. [8][9][10][11][12][13] The highly crystalline nature of BSP, however, limits its solubility below −60 °C, which explains the choice of this temperature for coupling reactions as opposed to the more convenient −78 °C achieved with dry ice/acetone cooling baths. This minor inconvenience and, more importantly, the recognition that liquid analogs of BSP might ultimately prove preferable in automated oligosaccharide synthesis applications requiring robotic dispensation prompted the synthesis and evaluation of other sulfinamides as described here.…”

Study of the Glycosidation Properties of 1‐Thiomannosazidopyranosides and 1‐Thiomannosaziduronic Acid Esters

“…Acetylation of diol 6 afforded O-3-benzylated glycoside 7. Chemo-and regioselective oxidation of the diol 6 using the TEMPO/BAIB {[bis(acetoxy)-iodo]benzene} reagent combination [23] afforded the corresponding mannosaziduronic acid 8 in 65 % yield. Methylation of the free carboxylic acid to give 9 and acetylation of the residual C-4 position afforded uronic ester donor 10 (Scheme 1).…”

Convergent synthesis of the hexasaccharide related to the repeating unit of the O-antigen from E. coli O120

“…The primary OH group thus obtained was oxidized to the corresponding uronic acid using TEMPO in the presence of iodosobenzene diacetate. 22 It is worth noting that the 4-methoxyphenyl group at the reducing end of the protected hexasaccharide remained unaffected by the TEMPO mediated oxidation. Next, the benzylidene and isopropylidene rings were hydrolyzed by 80% AcOH at 80 C. Further, the phthalimido functionality was converted to the required acetamido moiety by the treatment of ethylene diamine in presence of n-butanol 23 followed by acetylation using Ac 2 O and pyridine.…”