Synthesis and in vitro cytotoxicity of acetylated 3-fluoro, 4-fluoro and 3,4-difluoro analogs of D-glucosamine and D-galactosamine

• Štěpán Horník,
• Lucie Červenková Šťastná,
• Petra Cuřínová,
• Jan Sýkora,
• Kateřina Káňová,
• Roman Hrstka,
• Ivana Císařová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2016, 12, 750–759, doi:10.3762/bjoc.12.75

• configuration of 8 was confirmed by an increase in the value of 3JH2,H3 (1.6 → 11.1 Hz), a decrease in the value of 2JC5,F4 (27.2 → 18.3 Hz), and an increase of 3JH3,F4 coupling (4.3 → 26.0 Hz) between 22 and 8. To study the influence of 1-O-deacetylation on the cytotoxicity, the monofluorinated analogs 1, and

• 4–6 were subjected to anomeric deacetylation (Scheme 6). Compound 5 provided 1-O-deacetylated product 49 by treatment with BnNH2 in THF. Since acetylated 4-fluoro-D-GlcNAc 1 under these conditions did not react cleanly, we used piperidine-promoted [60] deacetylation to prepare 2 in 74% yield

• . Similarly, acetylated 4-fluoro-D-GalNAc 4 gave 50 in 60% yield. The attempted anomeric deacetylation of 3-fluoro-D-GalNAc 6 by treatment with piperidine followed by chromatography gave a fraction containing an inseparable side-product in addition to the expected deacetylated product 51. The side-product

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

• to the stereoselective glycoside synthesis. The final products were obtained by conventional Zemplén deacetylation. Keywords: diastereoselectivity; p-hydroxyphenylalkyl glycosides; mild promoters; natural products; 1,2-trans-glycosylation; Introduction Arylalkyl (substituted benzyl, phenethyl and

Total synthesis of panicein A₂

• Lili Yeung,
• Lisa I. Pilkington,
• Melissa M. Cadelis,
• Brent R. Copp and
• David Barker

Beilstein J. Org. Chem. 2015, 11, 1991–1996, doi:10.3762/bjoc.11.215

• its deacetylation product 20. The direct conversion of deacetylated product 20 to panicein A2 (5) through a modified Claisen rearrangement [19][20] was then attempted. Unfortunately, after heating 20 in toluene for 48 hours, no desired product 5 was obtained, with a complex mixture of compounds

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

• as a proof of structure. Substitution of the DMM group with an acetyl group was performed under standard conditions, i.e., treatment with NaOH for ring opening [39], HCl at pH 5 for amide cleavage, peracetylation and then O-deacetylation. Under these conditions, compound 17 was prepared in 37% yield

• successful cycloaddition step. Deacetylation of 19 afforded target spacer linked conjugate 20 in 75% yield. Unlike compound 16, the two C=O 13C NMR signals of conjugate 20 were clearly observed at δ = 174.28 ppm. Then, attention was given to prepare conjugate 24 (Scheme 5). This is to investigate the

Cross-metathesis reaction of α- and β-vinyl C-glycosides with alkenes

• Ivan Šnajdr,
• Kamil Parkan,
• Filip Hessler and
• Martin Kotora

Beilstein J. Org. Chem. 2015, 11, 1392–1397, doi:10.3762/bjoc.11.150

• prepared according to the previously reported procedure. A solution of penta-O-acetyl-D-galactose, allyltrimethylsilane and BF3·Et2O was refluxed in acetonitrile giving a 6:1 mixture of α- and β-epimers of 1-(tetra-O-acetyl-D-galactopyranosyl)prop-2-ene in 98% yield. Zemplén deacetylation afforded

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• subjected to the RCM with G-I (12) as a catalyst in CH2Cl2. Later, catalytic hydrogenation followed by deacetylation gave compound 141 (48%). Similarly, alkyne metathesis of compound 142 was carried out in the presence of Mo(CO)6 and 2-fluorophenol in chlorobenzene and heated under reflux to yield the

Synthesis of icariin from kaempferol through regioselective methylation and para-Claisen–Cope rearrangement

• Qinggang Mei,
• Chun Wang,
• Zhigang Zhao,
• Weicheng Yuan and
• Guolin Zhang

Beilstein J. Org. Chem. 2015, 11, 1220–1225, doi:10.3762/bjoc.11.135

• 3. The final procedure in completing the synthesis of icariin (1) is the removal of all acetyl groups in 14 (Scheme 4). In contrast to the traditional method for deacetylation under basic conditions such as with CH3ONa [15] or K2CO3 [33] in CH3OH, employing methanolic ammonia (7.0 M) for 3 h at room

N-Alkyl derivatives of diosgenyl 2-amino-2-deoxy-β-D-glucopyranoside; synthesis and antimicrobial activity

• Agata Walczewska,
• Daria Grzywacz,
• Dorota Bednarczyk,
• Małgorzata Dawgul,
• Andrzej Nowacki,
• Wojciech Kamysz,
• Beata Liberek and
• Henryk Myszka

Beilstein J. Org. Chem. 2015, 11, 869–874, doi:10.3762/bjoc.11.97

• THF, a procedure adopted from Zhang and Kováč [48]. This selective 1-O-deacetylation turned out to be very effective for 1a, 1b, and 1c (97%, 84%, and 90%, respectively). However, this was quite ineffective for 1d (36%). Therefore, 1-O-deacetylation of the latter was carried out via hydrolysis (Ag2CO3

Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

• Mathieu L. Lepage,
• Antoine Mirloup,
• Manon Ripoll,
• Fabien Stauffert,
• Anne Bodlenner,
• Raymond Ziessel and
• Philippe Compain

Beilstein J. Org. Chem. 2015, 11, 659–667, doi:10.3762/bjoc.11.74

• our group [11][12], the last stages of the multivalent probe synthesis involved the attachment of peracetylated azido iminosugars 4 on the scaffolds via CuAAC reaction and afterwards O-deacetylation using an anion exchange resin. First attempts to perform CuAAC reactions with triyne substrate 6b

• resulting from the cleavage of the carbon–boron bond in 6b. The same experimental protocol was applied to functionalized BODIPY 6a, leading to the desired trivalent cluster 12a in 83% yield. O-Deacetylation of compounds 12 using anion exchange Amberlite IRA-400 (OH−) resin provided the desired water-soluble

Synthesis of 1,2-cis-2-C-branched aryl-C-glucosides via desulfurization of carbohydrate based hemithioacetals

• Henok H. Kinfe,
• Fanuel M. Mebrahtu,
• Mandlenkosi M. Manana,
• Kagiso Madumo and
• Mokela S. Sokamisa

Beilstein J. Org. Chem. 2015, 11, 583–588, doi:10.3762/bjoc.11.64

• hemithioketals are well documented, the desulfurization of the related hemithioacetals (RCH(OH)SR) are less explored [20][21]. In achieving our goals, sulfoxide 2a synthesized from a controlled oxidation of thiochroman 1a was subjected to Pummerer rearrangement followed by Zemplén deacetylation to provide

• hemithioacetal 3a (Scheme 1). During the deacetylation reaction the hemithioacetal 3a precipitated out of the methanol solution. Although most hemithioacetals (RCH(OH)SR’) are usually unstable and difficult to isolate as they dissociate to their corresponding aldehydes and thiols [22], hemithioacetal 3a was

Selective methylation of kaempferol via benzylation and deacetylation of kaempferol acetates

• Qinggang Mei,
• Chun Wang,
• Weicheng Yuan and
• Guolin Zhang

Beilstein J. Org. Chem. 2015, 11, 288–293, doi:10.3762/bjoc.11.33

• /bjoc.11.33 Abstract A strategy for selective mono-, di- and tri-O-methylation of kaempferol, predominantly on the basis of selective benzylation and controllable deacetylation of kaempferol acetates, was developed. From the selective deacetylation and benzylation of kaempferol tetraacetate (1), 3,4′,5

• ,-tri-O-acetylkaempferol (2) and 7-O-benzyl-3,4′5,-tri-O-acetylkaempferol (8) were obtained, respectively. By controllable deacetylation and followed selective or direct methylation of these two intermediates, eight O-methylated kaempferols were prepared with 51–77% total yields from kaempferol

• . Keywords: benzylation; deacetylation; kaempferol; methylation; regioselectivity; Introduction Kaempferol [2-(4-hydroxyphenyl)-3,5,7-trihydroxychromen-4-one] (Figure 1) and its derivatives are widely distributed in plants such as beans, broccoli, strawberries, teas, and propolis [1][2]. They are well known

Synthesis and biological evaluation of a novel MUC1 glycopeptide conjugate vaccine candidate comprising a 4’-deoxy-4’-fluoro-Thomsen–Friedenreich epitope

• Manuel Johannes,
• Maximilian Reindl,
• Bastian Gerlitzki,
• Edgar Schmitt and
• Anja Hoffmann-Röder

Beilstein J. Org. Chem. 2015, 11, 155–161, doi:10.3762/bjoc.11.15

• ’-fluoro-TF SPPS building block 11 started by conversion of peracetylated D-glucose 1 into β-thio-glycoside 2 [45][46] under Lewis acid catalysis in 81% yield (Scheme 1). Subsequent Zemplén deacetylation [47], followed by 4,6-benzylidene acetal formation and acetylation provided fully protected precursor 3

Efficient deprotection of F-BODIPY derivatives: removal of BF₂ using Brønsted acids

• Mingfeng Yu,
• Joseph K.-H. Wong,
• Cyril Tang,
• Peter Turner,
• Matthew H. Todd and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2015, 11, 37–41, doi:10.3762/bjoc.11.6

• corresponding 3-amino- and 3-acetamido-F-BODIPY precursors, using ‘HCl-catalyzed deacetylation conditions’ (HCl in ethanol) to effect both deacetylation and deboration [34]. Conclusion In conclusion, we have serendipitously achieved efficient removal of the BF2 moiety from F-BODIPY derivatives using either the

Synthesis of divalent ligands of β-thio- and β-N-galactopyranosides and related lactosides and their evaluation as substrates and inhibitors of Trypanosoma cruzi trans-sialidase

• María Emilia Cano,
• Rosalía Agusti,
• Alejandro J. Cagnoni,
• María Florencia Tesoriero,
• José Kovensky,
• María Laura Uhrig and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 3073–3086, doi:10.3762/bjoc.10.324

• -6T), 35.2 (CH2NH), 31.4, 30.8 (CH2-CH2), 21.0 (2×), 20.8 (6×), 20.7 (2×) (CH3CO-); anal. calcd for C90H120N10O53·2H2O: C, 48.56; H, 5.61; N, 6.29; found: C, 48.20; H, 5.59; N, 6.01. HRMS–ESI (m/z): [M + H]+ calcd for C90H121N10O53, 2189.7075; found, 2189.7081. General procedure for O-deacetylation

Synthesis of modified cyclic and acyclic dextrins and comparison of their complexation ability

• Kata Tuza,
• László Jicsinszky,
• Tamás Sohajda,
• István Puskás and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2014, 10, 2836–2843, doi:10.3762/bjoc.10.301

• synthetic route was worked out via bromination, benzylation, deacetylation and debenzylation to obtain the 2-hydroxypropyl maltooligomer counterparts. The complexation properties of non-modified and modified cyclic and acyclic dextrins were studied and compared by photon correlation spectroscopy (PCS) and

Indium-mediated allylation in carbohydrate synthesis: A short and efficient approach towards higher 2-acetamido-2-deoxy sugars

• Christopher Albler,
• Ralph Hollaus,
• Hanspeter Kählig and
• Walther Schmid

Beilstein J. Org. Chem. 2014, 10, 2230–2234, doi:10.3762/bjoc.10.231

• azide reduction followed by final deacetylation using methanolic sodium methoxide furnishes the title compounds. Keywords: allylation; carbohydrates; epoxidation; indium; multivalent glycosystems; organocatalysis; Introduction The indium-mediated allylation of carbonyl compounds has proven to be a

• . Deacetylation in a methanolic HCl solution proved to be most efficient and the subsequent ozonolysis generated sugar azides 6a–c (Scheme 2). It turned out to be essential to perform the acidic acetate cleavage of compounds 5a–c under strictly dry conditions, since even small amounts of water promoted an

Expeditive synthesis of trithiotriazine-cored glycoclusters and inhibition of Pseudomonas aeruginosa biofilm formation

• Meriem Smadhi,
• Sophie de Bentzmann,
• Anne Imberty,
• Marc Gingras,
• Raoudha Abderrahim and
• Peter G. Goekjian

Beilstein J. Org. Chem. 2014, 10, 1981–1990, doi:10.3762/bjoc.10.206

• (propargylthio)triazine 2, using CuI and diisopropylethylamine (DIPEA) in DMF under microwave irradiation at 110 °C for 15 min. It provided the peracetylated D-galactopyanosyl cluster 9 in 73% yield. The peracetyl D-glucopyranosyl cluster 10 was similarly obtained in 92% yield. The deacetylation of the

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

• 4 and conversion to the desired glycosylation product 5. The presence of unreacted hydroxy ester 3 made purification of glycosylation product 5 difficult. Therefore, the crude reaction mixture was subjected to Zemplén deacetylation [24] to give intermediate 6, and the unreacted hydroxy ester 3 was

Clicked and long spaced galactosyl- and lactosylcalix[4]arenes: new multivalent galectin-3 ligands

• Silvia Bernardi,
• Paola Fezzardi,
• Gabriele Rispoli,
• Stefania E. Sestito,
• Francesco Peri,
• Francesco Sansone and
• Alessandro Casnati

Beilstein J. Org. Chem. 2014, 10, 1672–1680, doi:10.3762/bjoc.10.175

• dipolarophile-on-the-sugar approach [44]. The deprotection of compounds 9 and 13 from the acetyl groups was carried out by a transesterification reaction in the presence of CH3ONa in CH3OH at room temperature according to the standard Zemplén procedure. Complete deacetylation was achieved in 1 hour, as

• (150 W, 80 °C) facilitated the complete tetra-functionalization in only 40 minutes. Subsequent deacetylation with the Zemplén method led to target compounds 3 and 4, both of which were characterized by 1D and 2D NMR techniques and ESIMS analyses. Gal-3/glycocalixarenes interaction studies by SPR His6

Multivalent scaffolds induce galectin-3 aggregation into nanoparticles

• Candace K. Goodman,
• Mark L. Wolfenden,
• Pratima Nangia-Makker,
• Anna K. Michel,
• Avraham Raz and
• Mary J. Cloninger

Beilstein J. Org. Chem. 2014, 10, 1570–1577, doi:10.3762/bjoc.10.162

• and the changes in Mw upon deacetylation, enabling characterization of the average number of sugars per dendrimer [30]. Additional characterization details (including 1H NMR spectra) are provided in Supporting Information File 1. Characterization of dendrimer/galectin-3 aggregates Dynamic light

• mg, 2.20 μmol) solution. The mixture was stirred for 8 h at which point a 75 μL aliquot was collected and lyophilized for MALDI–TOF and NMR analysis. The remainder of the reaction mixture was lyophilized and subjected to the deacetylation procedure. This procedure for carbohydrate functionalization

• procedure for deacetylation to afford lactose-functionalized dendrimers To the lyophilized solid per-O-acetylated dendrimers, 1 mL of 1:1 water/methanol was added, at which point the dendrimer became a white precipitate. To this mixture was added 0.2 equiv of NaOMe (0.8 M in MeOH) for each peripheral

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

• attached to the anomeric center of the glucosamine moiety using oxazoline 6 [37][38][39]. Deacetylation and subsequent installation of the benzylidene protective group then gave alcohol 9. Coupling of 9 with (S)-2-chloropropanoic acid in the presence of sodium hydride resulted in the formation of protected

Synthesis of the first examples of iminosugar clusters based on cyclopeptoid cores

• Mathieu L. Lepage,
• Alessandra Meli,
• Anne Bodlenner,
• Céline Tarnus,
• Francesco De Riccardis,
• Irene Izzo and
• Philippe Compain

Beilstein J. Org. Chem. 2014, 10, 1406–1412, doi:10.3762/bjoc.10.144

• picrate to 9a indeed dramatically simplified the 1H NMR spectrum by inducing the formation of a sodium complex with a 6-fold symmetry (Figure 2ii). Subsequent O-deacetylation of compounds 9 using anion exchange Amberlite IRA-400 (OH−) resin provided the final deprotected iminosugar clusters 10 in high

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

• formanilide (R = H) or chloroacetanilide (R = CH2Cl) as a substrate (Scheme 10) produced the expected phosphoramidate by a mechanism which simultaneously involved deacetylation. The higher reactivity of formanilide and chloroacetanilide, when compared to aniline, was explained by the higher acidity of the

cis–trans Isomerization of silybins A and B

• Michaela Novotná,
• Radek Gažák,
• David Biedermann,
• Florent Di Meo,
• Petr Marhol,
• Marek Kuzma,
• Lucie Bednárová,
• Kateřina Fuksová,
• Patrick Trouillas and
• Vladimír Křen

Beilstein J. Org. Chem. 2014, 10, 1047–1063, doi:10.3762/bjoc.10.105

• /trans-isomer in the mixture from 1:4 to 1:2. Deacetylation of cis-23-O-acetylsilybins All pure cis-silybins were obtained as their C-23 acetates. The deacetylation proved to be rather difficult, as both acidic and basic hydrolysis as well as mild transesterification (NaOMe, MeOH) failed and/or resulted

Efficient carbon-Ferrier rearrangement on glycals mediated by ceric ammonium nitrate: Application to the synthesis of 2-deoxy-2-amino-C-glycoside

• Alafia A. Ansari,
• Y. Suman Reddy and
• Yashwant D. Vankar

Beilstein J. Org. Chem. 2014, 10, 300–306, doi:10.3762/bjoc.10.27

• subjected to deacetylation by using K2CO3/MeOH (Scheme 2) followed by the selective protection of the primary hydroxy group as a benzyl ether by using Bu2SnO and benzyl bromide in the presence of triethylamine and tetrabutylammonium iodide to afford alcohol 8 in 69% yield over 2 steps. The terminal olefin