A selective and mild glycosylation method of natural phenolic alcohols

• Mária Mastihubová and
• Monika Poláková

Beilstein J. Org. Chem. 2016, 12, 524–530, doi:10.3762/bjoc.12.51

• by the electron-withdrawing acetoxy group. On the contrary, the TMSOTf-promoted glycosylation [39] (method E) of coniferyl alcohol 12 with trichloroacetimidate 14 at low temperature was found to be more efficient and glycoside 23 was obtained in high yield with full β-selectivity as proved by NMR

Synthesis of D-fructose-derived spirocyclic 2-substituted-2-oxazoline ribosides

• Madhuri Vangala and
• Ganesh P. Shinde

Beilstein J. Org. Chem. 2015, 11, 2289–2296, doi:10.3762/bjoc.11.249

• Madhuri Vangala Ganesh P. Shinde Department of Chemistry, Indian Institute of Science Education and Research, Pune 411 008, India 10.3762/bjoc.11.249 Abstract The TMSOTf-mediated synthesis of β-configured spirocyclic 2-substituted-2-oxazoline ribosides was achieved using a “Ritter-like” reaction

• acetonitrile was shown, illustrating the instability of spirooxazolines in comparison with fused oxazolines [37]. In our work, the activation of the β-D-psicofuranose derivative 5a with TMSOTf in acetonitrile exclusively resulted in the formation of spirooxazoline 6a. The stability of this compound inspired us

• compounds 3a and 5a were utilized to check the substrate feasibility in the formation of spirooxazolines. In our first experiment, compound 5a was reacted with acetonitrile as a nucleophilic participating solvent using TMSOTf at 0 °C, then the reaction was left at room temperature for 1 h. To our delight

Synthesis, antimicrobial and cytotoxicity evaluation of new cholesterol congeners

• Mohamed Ramadan El Sayed Aly,
• Hosam Ali Saad and
• Shams Hashim Abdel-Hafez

Beilstein J. Org. Chem. 2015, 11, 1922–1932, doi:10.3762/bjoc.11.208

• ] was coupled with cholest-5-en-3β-ol (1) as glycosyl acceptor in the presence of catalytic TMSOTf as promoter to afford 15 in 74% yield. The large anomeric coupling constant (J1,2 = 8.4 Hz) of the pyranoside moiety at δ = 5.30 ppm ensured the β-configuration of this glycoside. Deacetylation of

• , 100 °C (9b, 47%); (b) CuSO4·5H2O, L-AsAc, THF/H2O [11a, n = 4 (90%); 11b, n = 9 (67%)]; (c) CBr4, PPh3, DCM (59%). Reagents and conditions: CuSO4·5H2O, L-AsAc, THF/H2O (96%). Reagents and conditions: (a) 1, TMSOTF, CH3CN, rt (74%); (b) NaOMe, MeOH (84%); (c) NaOH; HCl (pH 5); Ac2O/Pyr; NaOMe/MeOH (37

• %); (d) 9a, TMSOTf, DCM (71%); (e) 10, CuSO4·5H2O, L-AsAc, THF/H2O (67%); (f) NaOMe, MeOH (75%). Reagents and conditions: (a) 9a, TMSOTF, DCM, rt (19%); (b) 10, CuSO4·5H2O, L-AsAc, THF/H2O (62%); (c) NaOMe/MeOH (78%). A: Ring A of the maltose moiety, B: Ring B of the maltose moiety. Reagents & conditions

Towards inhibitors of glycosyltransferases: A novel approach to the synthesis of 3-acetamido-3-deoxy-D-psicofuranose derivatives

• Maroš Bella,
• Miroslav Koóš and
• Chun-Hung Lin

Beilstein J. Org. Chem. 2015, 11, 1547–1552, doi:10.3762/bjoc.11.170

• in traces as a mixture with the corresponding α-anomer 16 (Scheme 3). Further attempts to achieve the thioglycosylation of D-psicofuranose derivative 11 under various conditions, including EtSH/TMSOTf/CH2Cl2, EtSH/TMSOTf and EtSH/CSA/CH2Cl2 did not improve the yield of the required 2-thio-β-D

Automated solid-phase synthesis of oligosaccharides containing sialic acids

• Chian-Hui Lai,
• Heung Sik Hahm,
• Chien-Fu Liang and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2015, 11, 617–621, doi:10.3762/bjoc.11.69

• cycles were initiated following programmed maneuvers. Each cycle starts with a TMSOTf acidic wash at −20 °C to ensure that no base from previous deprotection reactions remains and quenches the subsequent coupling. This problem had been observed earlier (data not shown) and can be overcome by this extra

• washing step. In addition, TMSOTf eliminates any moisture that may have resided on the resin or in the reaction vessel. Glycosylations were carried out using the optimized temperatures for each building block using twice five equivalents of building block and activator. Removal of the Fmoc protecting

• linkages. Glycosylations: a) 2 × 5 equiv TMSOTf, ACN/DCM (1:1), −50 °C (5 min), −30 °C (10 min), −20 °C (80 min), −10 °C (10 min), 0 °C (10 min) for 4 and 5. b) 2 × 5 equiv TfOH, NIS, DCM, −40 °C (5 min), −20 °C (30 min) for 6 and 7. c) 2 × 5 equiv TMSOTf, DCM/dioxane (3:2), 20 °C (90 min), for 8. d) 2 × 5

Synthesis of a hexasaccharide partial sequence of hyaluronan for click chemistry and more

• Marina Bantzi,
• Stephan Rigol and
• Athanassios Giannis

Beilstein J. Org. Chem. 2015, 11, 604–607, doi:10.3762/bjoc.11.67

• ][23] was linked with glycosyl acceptor 2 [24][25] using TMSOTf as promoter to obtain disaccharide 4 in 90% yield. Likewise, reaction of glycosyl donor 1 with monosaccharide 3 [26] and subsequent O-TBS group cleavage with Olah's reagent [27], afforded disaccharide 5 in 86% yield. Thence, both

Articulated rods – a novel class of molecular rods based on oligospiroketals (OSK)

• Pablo Wessig,
• Roswitha Merkel and
• Peter Müller

Beilstein J. Org. Chem. 2015, 11, 74–84, doi:10.3762/bjoc.11.11

• –Martin-periodinane. iii: pentaerythritol, pTsOH (cat.). iv: 2-(4-methoxybenzyloxy)acetic acid, DCC, HOBt. v: (COCl)2/DMSO. vi: NaH, TMSCl, TMSOTf, vii DDQ, DCM, buffer pH 7). Synthesis of articulated rod 11 (i: CBr4, PPh3, NaN3. ii: K2CO3/MeOH. iii: Cu/C DCM/MeOH 1:1, cat. Et3N). Sequential deprotection

• of 11 and synthesis of triple articulated rod 14 (i: K2CO3/MeOH. ii: CBr4/PPh3/NaN3.iii: Cu/C, Et3N. iv: CBr4/PPh3/NaN3.). Synthesis of articulated rods 23–25 with increased solubility (i: 4-hydroxypiperidine, DCC, HOBt. ii: (COCl)2/DMSO. iii: 6, NaH, TMSCl, TMSOTf. iv: DDQ. v: K2CO3/MeOH. vi: CBr4

• /MeOH). Synthesis of articulated rods 32a–c (i: NaH, TMSCl, TMSOTf. ii: Cu/C, Et3N). Synthesis of articulated rods 33, 34 and 36. Synthesis of articulated rod 39 (i: cinnamoyl chloride, DMAP, pyridine. ii: DMF 120 °C). Synthesis of functionalized articulated rod 43 (i: PYBOP, Et3N. ii: KOH, H2O. iii

Synthesis of the pentasaccharide repeating unit of the O-antigen of E. coli O117:K98:H4

• Pintu Kumar Mandal

Beilstein J. Org. Chem. 2014, 10, 2724–2728, doi:10.3762/bjoc.10.287

• following the reaction pathway depicted in Scheme 2. Glycosylation of 3-azidopropyl 2,3,6-tri-O-benzyl-β-D-galactopyranoside (2) with the thioglycoside donor 3 in the presence of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethanesulfonate (TMSOTf) [26][27] gave disaccharide derivative 8 in 72

• . Reagents: (a) N-iodosuccinimide (NIS), TMSOTf, CH2Cl2, MS 4 Å, −30 °C, 1 h, 72%; (b) HClO4/SiO2, CH3CN, rt, 20 min, 85%; (c) benzoyl cyanide, DCM/pyridine, rt, 2 h, 80%; (d) N-iodosuccinimide (NIS), TfOH, CH2Cl2, MS 4 Å, −30 °C, 1 h, then 0 °C, 1 h, 77%; (e) NOBF4, Et2O/CH2Cl2 (3:1), −15 °C, 1 h, 75%; (f

A general metal-free approach for the stereoselective synthesis of C-glycals from unactivated alkynes

• Shekaraiah Devari,
• Manjeet Kumar,
• Ramesh Deshidi,
• Masood Rizvi and
• Bhahwal Ali Shah

Beilstein J. Org. Chem. 2014, 10, 2649–2653, doi:10.3762/bjoc.10.277

• , India 10.3762/bjoc.10.277 Abstract A novel metal-free strategy for a rapid and α-selctive C-alkynylation of glycals was developed. The reaction utilizes TMSOTf as a promoter to generate in situ trimethylsilylacetylene for C-alkynylation. Thanks to this methodology, we can access C-glycosides in a

• single step from a variety of acetylenes , i.e., arylacetylenes and most importantly aliphatic alkynes. Keywords: α-selective; C-alkynylation; glycal; metal free; TMSOTf; Introduction C-Glycosides represent an important class of carbohydrate mimics, owing to their presence in a large number of

• challenge. We reasoned that the development of a strategy which in situ activates the terminal alkyne and further catalyzes the reaction without the aid of other Lewis acids might be a solution to this problem. Thus, in continuation of our efforts [36][37][38], we describe a highly stereoselective TMSOTf

Structure/affinity studies in the bicyclo-DNA series: Synthesis and properties of oligonucleotides containing bc^en-T and iso-tricyclo-T nucleosides

• Branislav Dugovic,
• Michael Wagner and
• Christian J. Leumann

Beilstein J. Org. Chem. 2014, 10, 1840–1847, doi:10.3762/bjoc.10.194

• , quant.; (e) TBAF, THF, rt, 19 h, 95%; (f) thymine, BSA, SnCl4, CH3CN, 0 °C → rt, 17 h, 56% 7β + 22% (7α/β 2.5:1); (g) Bu4NOH, H2O/dioxane, rt, 16 h, 94%; (h) DMTrCl, pyridine, CH2Cl2, rt, 24 h, 98%; (i) CEP-Cl, DIPEA, THF, rt, 4 h, 89%. Conditions: (a) thymine, BSA, TMSOTf, TMSCl, CH3CN, rt, 2.5 h; (b

Convergent synthetic methodology for the construction of self-adjuvanting lipopeptide vaccines using a novel carbohydrate scaffold

• Vincent Fagan,
• Istvan Toth and
• Pavla Simerska

Beilstein J. Org. Chem. 2014, 10, 1741–1748, doi:10.3762/bjoc.10.181

• ) oxide to a solution of glycosyl bromide 2 and hydroxy ester 3, which yielded a mixture of orthoester byproduct 4 and desired glycosylation product 5 (Scheme 2). A catalytic amount of trimethylsilyl trifluoromethanesulfonate (TMSOTf) was added to the mixture, which resulted in ring-opening of orthoester

Concise total synthesis of two marine natural nucleosides: trachycladines A and B

• Haixin Ding,
• Wei Li,
• Zhizhong Ruan,
• Ruchun Yang,
• Zhijie Mao,
• Qiang Xiao and
• Jun Wu

Beilstein J. Org. Chem. 2014, 10, 1681–1685, doi:10.3762/bjoc.10.176

• was synthesized from commercial available 5-deoxy-1,2,3-tri-O-acetyl-β-D-ribofuranose (6) in 8 steps in 43.2% overall yield. Unfortunately, the Vorbrüggen glycosylation of carbohydrate 4 with bis(trimethylsilyl)hypoxanthine with TMSOTf as a catalyst afforded a mixture of inseparable N9 and N7 isomers

• -dichloropurine (18) afforded nucleoside 16 in 86% yield with DBU as a base and TMSOTf as a Lewis acid (Scheme 3). After heated in a pressure tube with ammonia saturated methanol, the benzoyl protecting groups were removed and the chlorine atom at position C6 was substituted at the same time to afford

• , 20% Pd(OH)2/C, Et3N, THF/EtOAc 1:1, rt, 91%; (g) Benzoyl chloride, DMAP (2 equiv), DCM, rt, 92%; (h) Ac2O/AcOH 1:1, H2SO4, rt, 84%. Synthesis of trachycladine B (2). Reagents and conditions: (a) i. N,O-Bis(trimethylsilyl)acetamide (BSA), MeCN; ii. TMSOTf, MeCN, 87%; (b) NH3 sat. methanol, 96%; (c

Bis(β-lactosyl)-[60]fullerene as novel class of glycolipids useful for the detection and the decontamination of biological toxins of the Ricinus communis family

• Hirofumi Dohi,
• Takeru Kanazawa,
• Akihiro Saito,
• Keita Sato,
• Hirotaka Uzawa,
• Yasuo Seto and
• Yoshihiro Nishida

Beilstein J. Org. Chem. 2014, 10, 1504–1512, doi:10.3762/bjoc.10.155

• )-fullerene has been prepared from lactosyl trichloroacetimidate 1 [26] following a pathway as shown in Scheme 1 [25]. The coupling reaction between 1 and 6-chloro-1-hexanol was conducted in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) to yield β-lactoside 2. The nucleophilic substitution

• dichloromethane (30 mL) was stirred for 1 h. After cooling to −40 °C, TMSOTf (53.8 μL, 0.298 mmol) was added to the suspension and the mixture was stirred for another 1 h. After quenching with triethylamine, the reaction mixture was diluted with chloroform and filtered through a Celite pad. The filtrate was

• . Reagents and conditions: (a) 6-chloro-1-hexanol, TMSOTf, CH2Cl2, −40 °C, 1 h, 48%; (b) NaN3, DMF, 60 °C, 16 h, 93%; (c) C60, chlorobenzene, reflux, 7 h, 14%; (d) NaOMe, CH2Cl2, MeOH, 5 h. Distribution (%) of ricin protein (0.1 mg mL−1) after sedimentation in the colloidal suspension of bis-Lac-C60 at

Efficient routes toward the synthesis of the D-rhamno-trisaccharide related to the A-band polysaccharide of Pseudomonas aeruginosa

• Aritra Chaudhury,
• Sajal K. Maity and
• Rina Ghosh

Beilstein J. Org. Chem. 2014, 10, 1488–1494, doi:10.3762/bjoc.10.153

• subsequently serve as the glycosyl donor in the next step. Accordingly, 5 and 6 were coupled almost quantitatively to give 8. The disaccharide so obtained was then coupled with 7 to give the protected trisaccharide 9 in 90% yield using a N-iodosuccinimide-trimethylsilyl trifluoromethanesulfonate (NIS-TMSOTf

• introduced into the reaction mixture at −50 °C after which NIS and TMSOTf were added successively at the same temperature. The temperature was then raised upto −10 °C, and the reaction mixture was stirred for another 1 h at that temperature to give the target trisaccharide as summarized in Scheme 3. At this

• would have similar reactivity towards glycosylative activation. Hence, a preactivation-based glycosylation protocol was devised for the first step leading to the disaccharide 11 using 1-benzenesulfinyl piperidine–triflic anhydride (BSP–Tf2O) [46]. The subsequent step was carried out using NIS–TMSOTf to

Design, automated synthesis and immunological evaluation of NOD2-ligand–antigen conjugates

• Marian M. J. H. P. Willems,
• Gijs G. Zom,
• Nico Meeuwenoord,
• Ferry A. Ossendorp,
• Herman S. Overkleeft,
• Gijsbert A. van der Marel,
• Jeroen D. C. Codée and
• Dmitri V. Filippov

Beilstein J. Org. Chem. 2014, 10, 1445–1453, doi:10.3762/bjoc.10.148

• . DEVA5K = DEVSGLEQLESIINFEKLAAAAAK. Potency of the NOD2-L antigen conjugates 2–5 in NOD2 transfected HEK cells. DC activation of the conjugates 2–5 and reference compounds 29 and 30. Antigen presentation of the conjugates 2–5 and reference compounds 29 and 30. a) TMSOTf, DCM, 83%; b) cat. NaOMe, MeOH

The Flögel-three-component reaction with dicarboxylic acids – an approach to bis(β-alkoxy-β-ketoenamides) for the synthesis of complex pyridine and pyrimidine derivatives

• Mrinal K. Bera,
• Moisés Domínguez,
• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 394–404, doi:10.3762/bjoc.10.37

• trimethylsilyl trifluoromethanesulfonate (TMSOTf) and triethylamine to provide the bis(4-hydoxypyridines) 16 in 50% yield and 18a in 60% yield, respectively (Scheme 3). A mechanistic proposal for this aldol type condensation has been presented in a previous report [53]. For precursor 14 partial monocyclization

• derivatives like 23b and 24b provided new synthetic options to construct unsymmetrically substituted mixed heteroaromatic systems. As an example we used mono-pyrimidine derivative 24b and cyclized its β-ketoenamide moiety by treatment with TMSOTf and triethylamine. Pyrimidine/pyridinol derivative 26 was

• -ketoenamides to 4-hydroxypyridines (typical procedure 2) Bis(β-ketoenamide) 14 (0.310 g, 0.57 mmol) was placed in an ACE-sealed tube and dissolved in DCE (10 mL). NEt3 (0.40 mL, 2.89 mmol) and TMSOTf (0.50 mL, 2.76 mmol) were added and the resulting mixture was stirred at 90 °C for 3 d. After cooling to rt the

Synthesis of new enantiopure poly(hydroxy)aminooxepanes as building blocks for multivalent carbohydrate mimetics

• Léa Bouché,
• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 213–223, doi:10.3762/bjoc.10.17

• coordination of the lithium cation to the nitrone oxygen is possible. The Lewis acid-induced rearrangements of 1,2-oxazines syn-7, syn-9 and syn-10 were achieved in moderate to good yields using TMSOTf as promoter (Scheme 4). A higher yield of 73% was achieved for the p-bromophenyl derivative 13 (isolated as a

• cooled to −5 °C and TMSOTf (1.35 mL, 7.46 mmol) was slowly added. After 5.5 h stirring at 0 °C, the dark red mixture was quenched with a solution of aq ammonia (5%) turning yellow. Work-up was performed with CH2Cl2 (3 × 30 mL). The combined organic layers were washed with brine, dried with Na2SO4

• skeleton by Lewis acid-induced rearrangement. Conditions: a) 1. TMSOTf, CH2Cl2, −5 °C, 5 to 6 h; 2. aq NH3, rt, 10 min. [TMSOTf = trimethylsilyl trifluoromethanesulfonate] Proposed extended chair-like conformation with Zimmerman–Traxler-type transition state. Synthesis of triols 14, 15 and 16 by reduction

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

• result was obtained upon treatment of the hydroxydioxepane, 3-methoxy-3-methyloctahydro-3H-benzo[c][1,2]dioxepin-9a-ol (179) with TMSOTf/Et3SiH. Thus, the peroxide moiety was not reduced with Et3SiH, and the reaction produced the bicyclic peroxide, 1-methyl-10,11,12-trioxatricyclo[7.2.1.04,9]dodecane

Synthesis of mucin-type O-glycan probes as aminopropyl glycosides

• David Benito-Alifonso,
• Rachel A. Jones,
• Anh-Tuan Tran,
• Hannah Woodward,
• Nichola Smith and
• M. Carmen Galan

Beilstein J. Org. Chem. 2013, 9, 1867–1872, doi:10.3762/bjoc.9.218

• and core 3 disaccharide precursors 14 and 15 were then prepared in the presence of catalytic TMSOTf in respective yields of 90% and 76%. Global deprotection of the assembled oligomers was achieved by a tandem process that required no purifications between steps, as the reactions proceeded cleanly as

• access disaccharide 20b, trichloroacetimidate glycoside donor 12 was reacted with 19 in the presence of catalytic TMSOTf to yield an inseparable mixture of disaccharide product 20a and unreacted starting material. Acetal cleavage with p-TsOH in MeOH under sonication followed by acetylation of the free OH

• and higher α-selectivities than other sialosyl donors [23]. Under our reaction conditions, sialylated disaccharide 22a was prepared as a 3/1 (α/β) mixture using 1-thioadamantyl sialoside 21 as the glycoside donor upon reaction with 19, using NIS in combination with catalytic TMSOTf to activate the

Bioinspired total synthesis of katsumadain A by organocatalytic enantioselective 1,4-conjugate addition

• Yongguang Wang,
• Ruiyang Bao,
• Shengdian Huang and
• Yefeng Tang

Beilstein J. Org. Chem. 2013, 9, 1601–1606, doi:10.3762/bjoc.9.182

• according to the literature methods. First of all, the 1,6-conjugate addition of 3 towards 4 was attempted by employing various conditions, including different basic conditions (NaH, DBU, KHMDS) by activation of the nucleophile 3 or acidic conditions (AcOH, TMSOTf, Sc(OTf)3 and In(OTf)3) by activation of

Synthesis of the tetracyclic core of Illicium sesquiterpenes using an organocatalyzed asymmetric Robinson annulation

• Lynnie Trzoss,
• Jing Xu,
• Michelle H. Lacoske and
• Emmanuel A. Theodorakis

Beilstein J. Org. Chem. 2013, 9, 1135–1140, doi:10.3762/bjoc.9.126

• under Meerwein’s conditions to afford β-ketoester 17. Treatment of 17 with TMSOTf/Et3N followed by enolate alkylation [82] under TBAF/MeI conditions afforded the desired C-5 quaternary center of 18 as a single isomer (35% over four steps). Global reduction of 18 with lithium aluminium hydride produced

Asymmetric synthesis of a highly functionalized bicyclo[3.2.2]nonene derivative

• Toshiki Tabuchi,
• Daisuke Urabe and
• Masayuki Inoue

Beilstein J. Org. Chem. 2013, 9, 655–663, doi:10.3762/bjoc.9.74

• triflate would cause highly unfavorable steric interactions. Indeed, the cycloaddition between 7 and acrolein proceeded even at −78 °C by the action of TMSOTf (50 mol %) in toluene to afford the bicyclo[3.2.2]nonene 8 and 20 along with a small amount of two other isomers 21ab (Table 1, entry 1). Among the

• various silyl triflates used (Table 1, entries 1–3), TBSOTf was found to be superior to TMSOTf or TIPSOTf in terms of the combined yield. Alteration of the amount of TBSOTf from 50 mol % (Table 1, entry 2) to 200 mol % (Table 1, entry 4) and change of the solvent from toluene (Table 1, entry 4) to CH2Cl2

• ), 9.37 (1H, d, J = 5.0 Hz, CHO); 13C NMR (125 MHz, CDCl3) δ −4.8, −4.2, 18.1, 24.1, 25.9, 29.7, 33.8, 34.1, 34.6, 38.0, 41.8, 50.6, 73.5, 134.1, 142.4, 204.3; HRMS–ESI (m/z): [M + Na]+ calcd for C18H32O2SiNa, 331.2064; found, 331.2057. Oxime 24: TMSOTf (220 μL, 1.2 mmol) was added to a solution of 8 (122

Synthesis and stability study of a new major metabolite of γ-hydroxybutyric acid

• Ida Nymann Petersen,
• Jesper Langgaard Kristensen,
• Christian Tortzen,
• Torben Breindahl and
• Daniel Sejer Pedersen

Beilstein J. Org. Chem. 2013, 9, 641–646, doi:10.3762/bjoc.9.72

• Information File 1). After heating at 90 °C for 72 h GBL starts to form at low concentration (indicated with arrows). Schmidt glucuronidation [11] with trichloroacetimidate 3. Synthesis of 4 and 5 using acceptors 7 and 8 was attempted several times by using BF3·OEt2, 3 Å MS, CH2Cl2, −20 °C to rt, and TMSOTf

Glycosylation efficiencies on different solid supports using a hydrogenolysis-labile linker

• Mayeul Collot,
• Steffen Eller,
• Markus Weishaupt and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 97–105, doi:10.3762/bjoc.9.13

• using five equivalents of the building block each time or were carried out three times by using three equivalents of the building block each time. Glycosyl trichloroacetimidate 34 was activated by catalytic amounts of trimethylsilyl trifluoromethanesulfonate (TMSOTf) at −15 °C in dichloromethane or

• ; 5. p-TsOH·H2O, MeOH, DCM, rt. Model glycosylation by using an automated oligosaccharide synthesizer. Reactions and conditions: (a) 34, TMSOTf, DCM, −15 °C (30 min); (b) 35, NIS, TfOH, DCM, dioxane, different temperatures and reaction times; (c) Pd(OAc)2, HCOONH4, H2O; (d) NaOMe, MeOH, DCM, rt

• . Glycosylation of 34 to linker 23 and subsequent Staudinger reduction of the azide. Reactions and conditions: (a) TMSOTf, DCM, −15 °C, 30 min; (b) PMe3, NEt3, H2O, THF, 25 °C, 30 min; (c) NaOMe, MeOH, DCM, rt. Functionalization of different resins with linker 1 and loading determination. Supporting Information

Synthesis of a derivative of α-D-Glcp(1->2)-D-Galf suitable for further glycosylation and of α-D-Glcp(1->2)-D-Gal, a disaccharide fragment obtained from varianose

• Carla Marino,
• Carlos Lima,
• Karina Mariño and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2012, 8, 2142–2148, doi:10.3762/bjoc.8.241

• in Et2O, employing TMSOTf as catalyst, proceeded with complete regio- and stereoselectivity, affording the α-glycosylaldonolactone 5 in 79% yield (Scheme 1). The α-anomeric configuration and the regioselectivity of the glycosylation were confirmed on the basis of the NMR spectra. In the 1H NMR

• (1.28 g, 1.88 mmol), 5,6-O-isoprolyliden-D-galactono-1,4-lactone (4, 0.48 g, 2.24 mmol) [16] and 4 Å powdered molecular sieves (0.5 g) in anhydrous Et2O (12 mL) was cooled to −78 °C, and TMSOTf (0.11 mL, 0.62 mmol) was slowly added. After 48 h of stirring at 5 °C, the mixture was quenched by addition of