Divergent Strategy for the Synthesis of α2-3-Linked Sialo-oligosaccharide Libraries Using a Neu5TFA-(α2-3)-Gal Building Block

Abstract

A novel Neu5TFA-(α2-3)-Gal building block with removable protecting group at N5′ was introduced and used in the divergent synthesis of a library of N-acetyl and N-glycolyl derivatives of oligosaccharides related to sialyl-(α2-3)-N-acetyl-lactosamine and sialyl-(α2-3)-N-acetyl-isolactosamine, with or without sulfate at O6 of glucosamine residue.

Key words

bioorganic chemistry - glycosides - glycosylation - ­protecting groups - sialic acids

• References and Notes

• 1a Schauer R. Biochemistry of Sialic Acid Diversity. In Carbohydrates in Chemistry and Biology . Part II, Vol. 3 Ernst B, Hart GW, Sinaÿ P. Wiley-VCH; Weinheim: 2000: 227-244
• 1b Angata T, Varki A. Chem. Rev. 2002; 102: 439
• 1c Varki A. Nature (London) 2007; 446: 1023

Recent reviews:
• 2a Boons G.-J, Demchenko AV. Chem. Rev. 2000; 100: 4539
• 2b Ress DK, Linhardt RJ. Curr. Org. Synth. 2004; 1: 31
• 2c Ando H, Imamura A. Trends Glycosci. Glycotechnol. 2004; 16: 293
• 2d De Meo C In Frontiers In Modern Carbohydrate Chemistry, ACS Symposium Series 960. Demchenko AV. American Chemical Society; Washington DC: 2007: Chap. 8, 118-131
• 2e De Meo C, Priyadarshani U. Carbohydr. Res. 2008; 343: 1540
• 2f Ando H. Trends Glycosci. Glycotechnol. 2008; 20: 141
• 2g Hanashima S. Trends Glycosci. Glycotechnol. 2011; 23: 111
• 2h Crich D. J. Org. Chem. 2011; 76: 9193
• 3a Uchinashi Y, Nagasaki M, Zhou J, Tanaka K, Fukase K. Org. Biomol. Chem. 2011; 9: 7243 ; and references cited therein
• 3b Chu K.-C, Ren C.-T, Lu C.-P, Hsu C.-H, Sun T.-H, Han J.-L, Pal B, Chao T.-A, Lin Y.-F, Wu S.-H, Wong C.-H, Wu C.-Y. Angew. Chem. Int. Ed. 2011; 50: 9391 ; and references cited therein
• 3c Harris BN, Patel PP, Gobble CP, Stark MJ, De Meo C. Eur. J. Org. Chem. 2011; 4023 ; and references cited therein
• 3d Premathilake HD, Gobble CP, Pornsuriyasak P, Hardimon T, Demchenko AV, De Meo C. Org. Lett. 2012; 14: 1126 ; and references cited therein
• 3e Wang Y, Xu F.-F, Ye X.-S. Tetrahedron Lett. 2012; 53: 3658 ; and references cited therein
• 4a Kononov LO, Malysheva NN, Kononova EG, Garkusha OG. Russ. Chem. Bull. 2006; 55: 1311
• 4b Kononov LO, Malysheva NN, Kononova EG, Orlova AV. Eur. J. Org. Chem. 2008; 3251
• 4c Kononov LO, Malysheva NN, Orlova AV. Eur. J. Org. Chem. 2009; 611
• 4d Kononov LO, Malysheva NN, Orlova AV, Zinin AI, Laptinskaya TV, Kononova EG, Kolotyrkina NG. Eur. J. Org. Chem. 2012; 1926 ; and references cited therein
• 5 Hanashima S, Sato K, Ito Y, Yamaguchi Y. Eur. J. Org. Chem. 2009; 4215
• 6 Crich D, Li W. Org. Lett. 2006; 8: 959
• 7a Sherman AA, Yudina ON, Komarova BS, Tsvetkov YE, Iacobelli S, Nifantiev NE. Synthesis 2005; 1783
• 7b Hanashima S, Castagner B, Esposito D, Nokami T, Seeberger PH. Org. Lett. 2007; 9: 1777 ; and references cited therein
• 7c Hanashima S, Seeberger PH. Chem. Asian J. 2007; 2: 1447
• 8a Pazynina GV, Sablina MA, Tuzikov AB, Chinarev AA, Bovin NV. Mendeleev Commun. 2003; 13: 245 ; and references cited therein
• 8b Esposito D, Hurevich M, Castagner B, Wang CC, Seeberger PH. Beilstein J. Org. Chem. 2012; 8: 1601 ; and references cited therein

Examples of syntheses of N-glycolyl-sialo-oligosaccharides:
• 9a Simeoni LA, Byramova NE, Bovin NV. Russ. J. Bioorg. Chem. 2000; 26: 183
• 9b Sherman AA, Yudina ON, Shashkov AS, Menshov VM, Nifantiev NE. Carbohydr. Res. 2002; 337: 451 ; and references cited therein
• 9c Crich D, Wu B. Org. Lett. 2008; 10: 403 ; and references cited therein
• 10 Huflejt ME, Vuskovic M, Vasiliu D, Xu H, Obukhova P, Shilova N, Tuzikov A, Galanina O, Arun B, Lu K, Bovin N. Mol. Immunol. 2009; 46: 3037
• 11 Although the α- and β-anomers of 3 can easily be separated by column chromatorgaphy on silica gel (10 → 60% EtOAc in benzene) and crystallization (Me₂CO–hexanes), their mixture can be used in the preparation of glycosyl bromide 4.
• 12 Paulsen H, Bünsch A. Carbohydr. Res. 1982; 100: 143
• 13 In all further calculations quantitative transformation of 3 to 4 was assumed.
• 14 Pazynina GV, Severov VV, Bovin NV. Russ. J. Bioorg. Chem. 2008; 34: 625
• 15 The glycosylation yields achieved with N-trifluoroacetyl glycosyl bromide 4 were comparable or slightly higher (5–11%) than those achieved earlier (ref. 8a) with the corresponding N-acetyl glycosyl bromide [Neu5Ac-(α2-3)-Gal building block], which was prepared from the parent glycosyl acetate by treatment with HBr in AcOH.
• 16 Typical Glycosylation Procedure A mixture of glycosyl acceptor (0.3 mmol), AgOTf (0.39 mmol), N,N,N′,N′-tetramethylurea (0.39 mmol), and freshly activated MS 4 Å (300 mg) in anhyd CH₂Cl₂ (7 mL) was stirred for 30 min at r.t. in the dark. Additional portion of MS 4 Å (100 mg) was added, and a solution of glycosyl bromide 4 (0.39 mmol) in anhyd CH₂Cl₂ (3 mL) was added. The mixture was stirred for 15–20 h and filtered, the filtrate was concentrated in vacuo, and the product was isolated by silica gel column chromatography.
• 17 In this particular case different amounts of glycosyl donor 4 (0.3 mmol) and glycosyl acceptor 5 (1.2 mmol) were used, all other conditions were the same as described in the typical procedure (ref. 16).
• 18 Deprotection of compounds 14, 18, 19, 26, and 29 under basic conditions involved treatment with MeONa in MeOH, followed by aq NaOH, neutralization with AcOH, and finally desalting by gel chromatography on Sephadex LH-20 (MeCN–H₂O, 1:1) gave compounds 15, 20, 21, 30, and 31 with the NH₂ group at C5 of the sialic acid residue and the latent amino group in the spacer aglycon (N₃ or NHBoc) in virtually quantitative yields.
• 19 In order to remove O-acyl substituent in glycolyl fragment, the initially formed product was treated with aq NaOH, neutralized with AcOH, and only then was the product isolated by gel chromatography on Sephadex LH-20 (MeCN–H₂O, 1:1).
• 20 Compounds 16, 24, 25, 32, and 33 (internal salts) were isolated from the reaction mixtures by ion-exchange chromatography on Dowex 50W × 4 resin (H⁺ form; elution with 1 M aq pyridine).
• 21 Oligosaccharides 16, 24, and 25 were additionally purified by reversed-phase HPLC (Phenomenex Luna C18, 5 μm particle size, 100 Å pore size) by elution with H₂O.
• 22 Choudhury Mukherjee I, Minoura N, Uzawa H. Carbohydr. Res. 2003; 338: 1265
• 23 Treatment of 6 with AcCl generated the corresponding acetylated glycosyl chloride 7, which was further reacted with alcohol 5 to give the mixture of anomeric 3-chloropropyl glycosides 8. The β-glycoside was separated by crystallization (EtOAc–Et₂O–hexanes) and chromatography of the mother liquor (silica gel, 5 → 30% Me₂CO in benzene), then chlorine in the aglycon was substituted with azide (→ 9), and after de-O-acetylation (→ 10) 4,6-O-benzylidene acetal was installed selectively to give the target 3-OH alcohol 11 in 28% overall yield. Acetylation of the single hydroxyl group in 11 followed by regioselective reductive ring opening of the benzylidene acetal in 12 with NaBH₃CN–MsOH in THF²⁴ gave the target 4-OH alcohol 13 in 58% overall yield.
• 24 Zinin AI, Malysheva NN, Shpirt AM, Torgov VI, Kononov LO. Carbohydr. Res. 2007; 342: 627
• 25 Glycosylation of secondary hydroxy groups at C3 and especially at C4 of N-acetylglucosamine residue is considered difficult (see ref. 26).
• 26a Paulsen H. Angew. Chem., Int. Ed. Engl. 1982; 21: 155
• 26b Debenham J, Rodebaugh R, Fraser-Reid B. Liebigs Ann./Recl. 1997; 791
• 26c Crich D, Dudkin V. J. Am. Chem. Soc. 2001; 123: 6819
• 27a Pazynina GV, Severov VV, Maisel ML, Belyanchikov IM, Bovin NV. Mendeleev Commun. 2008; 18: 238
• 27b Pazynina G, Sablina M, Mayzel M, Nasonov V, Tuzikov A, Bovin N. Glycobiology 2009; 19: 1078
• 28 Sulfated derivatives 22, 23, 34, and 35 were isolated by ion-exchange chromatography on DEAE Sephadex A-25 (OAc^– form; elution with 1 M aq pyridine–AcOH, pH 6.5). After freeze-drying and ion-exchange on Dowex 50W × 4 resin (Na⁺ form, elution with H₂O) the corresponding Na⁺ salts were obtained.
• 29 Treatment of the N-Boc derivatives of trisaccharides with TFA was accompanied by concomitant formation of the corresponding lactones, which were hydrolyzed with aq NaOH (excess NaOH was neutralized with AcOH) prior to isolation of the target spacered trisaccharides 34 and 35.
• 30 Analytical Data of Sulfated Oligosaccharides Compound 22: [α]_D ²⁵ –0.2 (c 0.42, MeCN–H₂O = 1:1). ¹H NMR (700 MHz, D₂O): δ = 1.82 (dd ≈ t, J = 12.1 Hz, 1 H, H-3_ax′′), 1.99 (m, 2 H, CH₂ sp), 2.07 (s, 3 H, NCOMe), 2.81 (dd, J _3eq,3ax = 12.5 Hz, J _3eq,4 = 4.6 Hz, 1 H, H-3_eq′′), 3.142 (m ≈ t, J = 6.9 Hz, 2 H, NCH₂ sp), 3.57 (dd, J _1,2 = 7.9 Hz, J _2,3 = 9.8 Hz, 1 H, H-2′), 3.63 (m, 2 H, H-7′′, H-4), 3.67 (dd, J _9a,9b = 11.9 Hz, J _8,9b = 6.1 Hz, 1 H, H-9b′′), 3.70 (ddd ≈ dd, J _5,6a = 3.9 Hz, J _5,6b = 8.2 Hz, 1 H, H-5′), 3.73–3.93 (m, 10 H), 3.96 (dd ≈ t, J = 10.2 Hz, 1 H, H-5′′), 3.97 (dd ≈ d, J = 3.1 Hz, 1 H, H-4′), 4.03 (m, 1 H, OCH sp), 4.12 (dd, J _2,3 = 9.8 Hz, J _3,4 = 3.1 Hz, 1 H, H-3′), 4.15 (s, 2 H, CH₂ Gc), 4.25 (dd, J _5,6b = 5.9 Hz, J _6a,6b = 11.3 Hz, 1 H, H-6b), 4.41 (dd, J _5,6a = 1.9 Hz, J _6a,6b = 11.3 Hz, 1 H, H-6a), 4.54 (d, J _1,2 = 7.9 Hz, 1 H, H-1′), 4.60 (d, J _1,2 = 8.5 Hz, 1 H, H-1). ¹³C NMR (176 MHz, D₂O): δ = 22.4, 26.7, 37.8, 39.9, 51.4, 54.4, 61.1 (2 C), 62.5, 67.3, 67.3, 68.1, 68.2, 68.3, 68.6, 69.2, 71.9, 72.6, 73.3, 75.2, 75.7, 82.2, 99.7, 101.1, 103.5, 173.9, 174.8, 175.8. ESI-HRMS: m/z calcd for C₂₈H₄₈N₃O₂₃S [M⁻]: 826.2405; found: 826.2402. Compound 34: [α]_D ²⁵ –7 (c 0.46, MeCN–H₂O = 1:1). ¹H NMR (700 MHz, D₂O): δ = 1.80 (dd ≈ t, J = 12.1 Hz, 1 H, H-3_ax′′), 1.94 (m, 2 H, CH₂ sp), 2.02 (s, 3 H, NCOMe), 2.75 (dd, J _3eq,3ax = 12.4 Hz, J _3eq,4 = 4.6 Hz, 1 H, H-3_eq′′), 3.10 (m ≈ t, J = 6.8 Hz, 2 H, NCH₂ sp), 3.54 (dd, J _1,2 = 7.9 Hz, J _2,3 = 9.8 Hz, 1 H, H-2′), 3.58 (dd, J _6,7 = 1.4 Hz, J _7,8 = 9.2 Hz, 1 H, H-7′′), 3.63 (dd, J _8,9b = 5.9 Hz, J _9a,9b = 12.0 Hz, 1 H, H-9b′′), 3.69–3.81 (m, 10 H), 3.87 (dd, J _9a,9b = 12.1 Hz, J _8,9a = 2.2 Hz, 1 H, H-9a′′), 3.89–3.93 (m, 2 H, H-5′′, H-8′′), 3.95 (dd ≈ d, J = 2.9 Hz, 1 H, H-4′), 3.97 (m, 1 H, OCH sp), 4.10 (s, 3 H, CH₂ Gc), 4.11 (dd, J _2,3 = 9.9 Hz, J _3,4 = 3.0 Hz, 1 H, H-3′), 4.31 (dd, J _5,6a = 4.4 Hz, J _6a.6b = 11.2 Hz, 1 H, H-6a), 4.42 (dd ≈ d, J = 11.2 Hz, 1 H, H-6b), 4.53 (d, J _1,2 = 8.4 Hz, 1 H, H-1), 4.58 (d, J _1,2 = 7.8 Hz, 1 H, H-1′). ¹³C NMR (176 MHz, D₂O): δ = 22.2, 26.7, 37.9, 39.7, 51.5, 55.1, 61.1, 61.1, 62.6, 66.4, 67.5, 68.1, 68.2, 68.3, 69.5, 71.6, 72.2, 72.6, 72.7, 75.2, 75.4, 77.5, 99.8, 101.4, 102.3, 174.0, 174.8, 175.8. ESI-HRMS: m/z calcd for C₂₈H₄₈N₃O₂₃S [M^–]: 826.2405; found: 826.2402.
• 31 For analytical data of other target oligosaccharides and key intermediates, see Supporting Information.