Synthesis of the tetrasaccharide repeating unit of the cryoprotectant capsular polysaccharide from Colwellia psychrerythraea 34H

Abstract

Synthesis of the threonine-decorated tetrasaccharide repeating unit of a cryoprotectant polysaccharide with a glycosaminoglycan-like structure.

Synthesis of the pentasaccharide repeating unit of the O-antigen from Enterobacter cloacae C4115 containing the rare α-d-FucNAc

“…Unfortunately, glycosylation between galactosyl donor 16 and acceptor 13 through activation of thioglycoside using NIS in the presence TMSOTf failed to provide the disaccharide. Instead, it led to an undesired derivative 17 formed via intra-molecular C-glycosidation [25][26][27] (see Scheme S1 in ESI †).…”

“…[a] 25 D +44 (c 0.8, CHCl 3 ). 1 To a solution of the substrate 9 (400 mg, 1.04 mmol) dissolved in CH 2 Cl 2 (20 mL), dimethoxymethane (0.16 mL, 2.1 mmol) and p-TSA (40 mg, 0.2 mmol) were added and the reaction mixture was reuxed for 12 hours.…”

Recent progress in chemical synthesis of bacterial surface glycans

“…Synthetic targets chemically obtained include repeating units (RUs) and related oligomers or analogs of CPSs (1-25) [10,12,[19][20][21][22][23][24][25][26][46][47][48][49][50][51][52][53][54][55][56][57][58][59], LPSs and LOSs [28][29][30][31][32][33][34][35][36][37][60][61][62][63][64][65][66][67][68][69][70][71][72], cell wall polysaccharides (50)(51)(52)(53)…”

“…The CPS oligosaccharides and analogs obtained (Figure 2A) include those from Hib (1) [19]; S. pneumoniae (Sp) serotypes ST1 (2) [20] ** , ST2 (3) [10], ST3 (4)(5) [21] ** , ST5 (6) [46], ST8 (7a-7d) [12] ** , ST11A (8) [22], and ST12F (9) [47]; group B Streptococcus (GBS) or Streptococcus agalactiae types Ia (10) [23], II (11) [24], VII (12) [25]; carbapenem-resistant Klebsiella pneumoniae (CR-Kp) (13) [26]; A. baumannii K47 (14) [48]; S. aureus types 5 (15) [49,61] and strain M (16) [50]; B. mallei (17) [51,52]; C. jejuni RM1221 (18) [53] ** and 81-176 (19) [54]; Bacteroides fragilis CPS PS A1 RU (20) [55]; Morganella morganii (21) [56]; C. bolteae (22) [27] ** , K. kingae KK01 (23) [57], C. psychrerythraea 34H (24) [58] and S. typhi (25) [59]. Among these, compounds 2, 20, 21, and 45 are repeating units of zwitterionic polysaccharides (ZPSs).…”

Solvent-Free Approaches in Carbohydrate Synthetic Chemistry: Role of Catalysis in Reactivity and Selectivity

“…These methodologies offered interesting opportunities compared to described methods in solution, with successful applications also with unusual carbonyl precursors as acetalating/ketalating agents: cyclohexanone, furfural, nonanal, o-vanillin, and 2-naphtyl aldehyde. A direct comparison with a standard in-solvent protocol emphasized that the (2-naphthyl)methylidene installation, a useful protection in synthetic carbohydrate chemistry, is better performed with the above-mentioned aldehyde/orthoester method, and this approach was recently exploited in synthetic projects aimed at the preparation of oligosaccharides of biological interest [40,41].…”