Solid-phase synthesis of core 2 O-linked glycopeptide and its enzymatic sialylation

Solid-Phase Synthesis of Core 8O-Glycan-Linked MUC5AC Glycopeptide

“…The discovery of appropriate acidic conditions for cleavage of the benzyl groups have made our syntheses of several glycopeptides carrying core 1 [4][5][6] and core 2 O-glycans [7][8][9] successful. Our synthetic studies were then directed toward the other core class glycan displayed on the mucin peptide backbone.…”

Efficient Synthesis of the Lewis A Tandem Repeat

“…The trisaccharide was designed as the suitably protected form equipped with TBDPS group on the 1-position of the glucosamine and an allyl group on the 3-position of the galactose for divergent synthesis of the acceptor and the donor. In addition, the trichloroacetyl (TCA) group on the 2-position of the glucosamine and the benzyl groups were expected to ensure high stereoselectivity and high yield during the later glycosylation [4,[6][7][8][9][10][11][12][13]. We envisioned that the tetramer could be obtained by glycosylation promoted by a catalytic Lewis acid with haxasaccharyl acceptor and donor, which could be prepared from the hexasaccharide Le a dimer, and the hexasaccharide could be synthesized by coupling the acceptor and N-phenyl trichloroacetimidyl donor provided from the Le a trisaccharide common intermediate (Scheme 1).…”

“…19 (m, 2H, H2C=CHCH2, H-1 ), 5.12-5.10 (m, 2H, H-1 Fuc , H-4 , PhCH2), 4.68 (d, 1H, PhCH2), 4.53 (d, 1H, PhCH2), 4.47-4.35 (m, 5H, PhCH2 × 4, H-1 Gal ), 4.22-4.11 (m, 3H, H-3 GlcN , H2C=CHCH2 × 2), 3.92 (t, 1H, J3,4 = J4,5 = 9.4 Hz, H-4 GlcN ), 3.85-3.80 (m, 2H, H-2 Fuc , H-4 Gal ), 3.70-3.56 (m, 4H, H-6a Gal , H-6b Gal , H-6a GlcN , H-2 Gal ), 3.34 (dd, 1H, J5,6a = 4.9 Hz, J5,6b = 8. 7 Hz, H-5 Gal ), 3. 30 (dd, 1H, J2,3 = 9.8 Hz, J3,4 = 2.8 Hz, H-3 Gal ), 3.22-3.19 (m, 2H, H-6b GlcN , H-2 (11). To a solution of 10 (9.32 g, 6.87 mmol) in pyridine (458 mL) was added acetic anhydride (458 mL) at 0 °C under Ar,…”

Advances in chemical ligation strategies for the synthesis of glycopeptides and glycoproteins

“…110 Once assembled the glycopeptide thioester was cleaved from the resin using a TFA-based cocktail and further treated with ''low TfOH'' to debenzylate the glycans. [110][111][112][113] Glycopeptide thioester 63 was initially ligated to tripeptide 64 (TQT-NH 2 ) using the thioester method (HOOBt, DIEA and AgCl) before treatment with piperidine to remove the N-terminal Fmoc-carbamate providing 65. This was further elaborated by five iterative ligation and deprotection cycles with 63 under the same silver-mediated coupling conditions to afford glycoprotein 66 bearing six copies of the basal MUC2 repeat.…”