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Search for "acetylation" in Full Text gives 222 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Synthesis of the pentasaccharide repeating unit of the O-antigen of E. coli O117:K98:H4
Beilstein J. Org. Chem. 2014, 10, 2724–2728, doi:10.3762/bjoc.10.287
- the removal of the benzyl group was accomplished by hydrogenation using Pearlman’s catalyst [36]. Finally the acetates were removed by Zemplén de-O-acetylation [37] using sodium methoxide to afford the target pentasaccharide 1 in 58% overall yield (Scheme 2). Conclusion In summary, a [3 + 2] block
Gold(I)-catalysed synthesis of a furan analogue of thiamine pyrophosphate
Beilstein J. Org. Chem. 2014, 10, 2580–2585, doi:10.3762/bjoc.10.270
- strong inhibitor of ZmPDC with picomolar affinity. Friedel–Crafts acetylation of the furan at C-2 was successful which opens the possibility of synthesising furan analogues of the enzymic reaction intermediates. Structure of thiamine diphosphate (ThDP, 1). Time course inactivation of ZmPDC by various
A simple copper-catalyzed two-step one-pot synthesis of indolo[1,2-a]quinazoline
Beilstein J. Org. Chem. 2014, 10, 2441–2447, doi:10.3762/bjoc.10.254
- ]quinazoline derivatives. (3) This protocol is performed as a two-step reaction in one pot. Results and Discussion Substituted N-(2-iodophenyl)acetamides 1 were synthesized from substituted 2-iodoaniline by acetylation [31][32]. Substituted o-iodobenzaldehydes 3 were prepared from 2-iodobenzoic acid
Synthesis of novel conjugates of a saccharide, amino acids, nucleobase and the evaluation of their cell compatibility
Beilstein J. Org. Chem. 2014, 10, 2406–2413, doi:10.3762/bjoc.10.250
- . Synthesis Schemes 1–4 show the syntheses of the SAN conjugates formed by the reaction of the amino acid segment with the nucleobase and the saccharide derivative. The key steps include N-alkylation, acetylation, solid-phase peptide synthesis (SPPS) and N-hydroxysuccinimide (NHS)/N,N-diisopropylcarbodiimide
Synthesis and immunological evaluation of protein conjugates of Neisseria meningitidis X capsular polysaccharide fragments
Beilstein J. Org. Chem. 2014, 10, 2367–2376, doi:10.3762/bjoc.10.247
- performed at an early stage of the synthetic route than on valuable advanced intermediates. Accordingly, the azide reduction with NiCl2/NaBH4 protocol [29] occurred smoothly on the previously described [25] silyl glycoside 4, and after standard N-acetylation furnished acetamide 5 in high yield (Scheme 1
Expanding the scope of cyclopropene reporters for the detection of metabolically engineered glycoproteins by Diels–Alder reactions
Beilstein J. Org. Chem. 2014, 10, 2235–2242, doi:10.3762/bjoc.10.232
- sugars 1 and 2 we neutralized the corresponding hexosamine hydrochlorides 5 and 6 with sodium methoxide and coupled them to the activated cyclopropene 7 (Scheme 2), the synthesis of which we reported previously [24]. Subsequent acetylation of the carbamates 8 and 9 gave Ac4GlcNCyoc (1) and Ac4GalNCyoc (2
- anhydride (10 mL) was added. After stirring for 24 h at room temperature additional 5 mL acetic anhydride were added to complete the acetylation. After additional 24 h the solvents were evaporated under reduced pressure. The residue was dissolved in CH2Cl2 (250 mL), washed with 10 % aq KHSO4 (200 mL), satd
Indium-mediated allylation in carbohydrate synthesis: A short and efficient approach towards higher 2-acetamido-2-deoxy sugars
Beilstein J. Org. Chem. 2014, 10, 2230–2234, doi:10.3762/bjoc.10.231
- reaction furnished olefins 2a and 2b after acetylation in quantitative yield (Scheme 1). In the gluco-case a yield of 70% for 2c was obtained owing to incomplete consumption of the starting material 1c. Ozonolysis of the olefins 2 was performed using thiourea as reducing agent. Subsequently the generated 2
- followed by N-acetylation with N-acetoxyphthalimide did not afford products 8a–c in acceptable yields and/or purity. Since compounds 8a–c could not be purified by conventional silica gel chromatography we decided to perform an additional acetylation step in order to avoid reversed-phase HPLC and to
Synthesis and optical properties of pyrrolidinyl peptide nucleic acid carrying a clicked Nile red label
Beilstein J. Org. Chem. 2014, 10, 2166–2174, doi:10.3762/bjoc.10.224
- completion of the synthesis, the N-terminal Fmoc group was removed and the free amino group was capped by acetylation. The acpcPNA on the solid support was spilt to 0.5 µmol portions for a further labeling experiment and treated with 1:1 dioxane/aqueous NH3 at 60 °C overnight to remove the nucleobase- and
Chiral phosphines in nucleophilic organocatalysis
Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218
Palladium-catalysed cyclisation of alkenols: Synthesis of oxaheterocycles as core intermediates of natural compounds
Beilstein J. Org. Chem. 2014, 10, 2077–2086, doi:10.3762/bjoc.10.216
- olefination using diethyl carbethoxyethylidenephopsphonate. Reduction of the resultant ester with DIBAL-H in dichloromethane afforded partially protected triol 36 in 39% yield over five steps. Finally, acetylation of the primary hydroxy group and subsequent removal of the acetonide provided the target
- compound 37 in good yield (77%). Synthesis of the similar substrate rac-42 having two conjugated double bonds is shown in Scheme 5. The synthesis started from the known acetate 38, which was obtained by acetylation of commercially available non-3-ene-1-ol [34]. Epoxidation of acetate 38 with MCPBA in
Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement
Beilstein J. Org. Chem. 2014, 10, 1942–1950, doi:10.3762/bjoc.10.202
- that the application of these reagents favours the addition of Grignard reagents to carbonyl compounds to afford higher yields [20][21][22]. Since all attempts to separate and purify carbinols 4–7 using column chromatography were unsuccessful even after acetylation, their physical and spectral data are
Supercritical carbon dioxide: a solvent like no other
Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196
- ) (PMA - Table 2, compound 22) has a greater degree of acetylation than poly(vinyl acetate) (PVAc - Table 2, compound 23) but has a much higher melting point and is insoluble in CO2 [84]. A significant amount of experimental and theoretical work has been carried out on the addition of CO2-philic moieties
Multicomponent reactions in nucleoside chemistry
Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179
- showed that the acetylation of the furanose hydroxy groups resulted in a dramatic decrease in anti-leishmanian activity from 10.6 ± 1.3 µM (63a) to 139 µM (64b). Compound 65 was active against the cowpox virus in human foreskin fibroblast cells (EC50 = 2.0 ± 0.3 µM) [93] and showed anti-leishmanian
Orthogonal dual thiol–chloroacetyl and thiol–ene couplings for the sequential one-pot assembly of heteroglycoclusters
Beilstein J. Org. Chem. 2014, 10, 1557–1563, doi:10.3762/bjoc.10.160
- α-D-ManSH 1 and β-D-GlcNAcSH 2 were prepared from the corresponding bromo peracetyl and chloro peracetyl sugars by treatment with potassium thioacetate followed by de-O-acetylation under standard conditions [24]. Cyclopeptide 3 displaying two orthogonal functionalities, i.e., four lysine residues
Synthesis and solvodynamic diameter measurements of closely related mannodendrimers for the study of multivalent carbohydrate–protein interactions
Beilstein J. Org. Chem. 2014, 10, 1524–1535, doi:10.3762/bjoc.10.157
- follow a conceptually identical strategy to the one described above for trimers 5 and 9. Toward this goal, propargylated 9-mer scaffold 10 [17] was treated under the same CuAAc conditions with azide 3 to provide peracetylated 11 in 83% yield which upon Zemplén de-O-acetylation gave 12 in essentially
- :0 to 90:10) afforded the desired glycocluster. Procedure B: Zemplén de-O-acetylation procedure for insoluble hydroxylated derivatives The acetylated compound was dissolved in anhydrous MeOH and a solution of sodium methoxide (1 M in MeOH, 5 µL every 20 min until precipitation) was added. An
Design, automated synthesis and immunological evaluation of NOD2-ligand–antigen conjugates
Beilstein J. Org. Chem. 2014, 10, 1445–1453, doi:10.3762/bjoc.10.148
- neopentyl glycol at 60 °C and careful monitoring of the reaction progress led to compound 17 in 88% yield. Acetylation of 17 then afforded compound 18. Stabilization of the glycosidic linkage by the installment of electron-withdrawing groups proved to be successful, and the treatment of 18 with 20% TFA in
Carbohydrate PEGylation, an approach to improve pharmacological potency
Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147
- and chitosan derivatives for pharmaceutical applications was described [22]. Chitosan is the polysaccharide obtained from the abundant chitin by alkali or enzymatic degradation. It consists of a backbone of β-(1→4)-linked D-glucosamine units with a variable degree of N-acetylation. The protonated
A complete series of 6-deoxy-monosubstituted tetraalkylammonium derivatives of α-, β-, and γ-cyclodextrin with 1, 2, and 3 permanent positive charges
Beilstein J. Org. Chem. 2014, 10, 1390–1396, doi:10.3762/bjoc.10.142
- ], acetylation [11] or hydroxypropylation [12] and perfacial substitution of all primary 6-OH hydroxy groups by iodine [13]. The products of these reactions are easily accessible in high amounts and are used in the pharmaceutical industry [14] or as precursors for further derivatizations. Monosubstituted CDs
Tandem Cu-catalyzed ketenimine formation and intramolecular nucleophile capture: Synthesis of 1,2-dihydro-2-iminoquinolines from 1-(o-acetamidophenyl)propargyl alcohols
Beilstein J. Org. Chem. 2014, 10, 1255–1260, doi:10.3762/bjoc.10.125
- another internal nucleophile in the same distance (6-membered) as a competitor. Results and Discussion Thus, we synthesized a substrate 3 (from 1 via 2a) through Grignard reaction followed by acetylation (Scheme 2). Substrate 3 contains two nucleophiles in the form of acetyl and acetamide groups at equal
Synthesis of zearalenone-16-β,D-glucoside and zearalenone-16-sulfate: A tale of protecting resorcylic acid lactones for regiocontrolled conjugation
Beilstein J. Org. Chem. 2014, 10, 1129–1134, doi:10.3762/bjoc.10.112
- phase transfer conditions led to complex product mixtures (Scheme 2C). Nevertheless, the procedure for selective acetylation of resorcylic acid esters and lactones was applied for the first synthesis of 14-O-acetylzearalenone (14) (Scheme 3). To avoid undesired cleavage of the acetyl group during
- ) and ZEN-16-sulfate (8). Sulfates shown as sodium salts. General strategy for the synthesis of RAL-2’-conjugation (Pg: protective group, pGlc: protected glucose moiety, pS: protected sulfate, Glc: β,D-glucoside). (A) Regioselective acetylation of resorcylic acid ester 9. (B) Lewis acid mediated
- glucosylation; no conversion of 10, partially rearrangement of 11 to glucosyl acetamide 12. (C) Königs–Knorr glucosylation; Ag(I): Ag2CO3 or Ag2O, CH2Cl2 or MeCN; PTG: phase transfer glucosylation, NaOH, tetrabutylammonium bromide, pH 10–11, CHCl3/H2O. Regioselective acetylation of ZEN (1) affording 14-O
cis–trans Isomerization of silybins A and B
Beilstein J. Org. Chem. 2014, 10, 1047–1063, doi:10.3762/bjoc.10.105
- decomposed, and in CHCl3 the reaction failed. In EtOAc, the reaction was accompanied by C-23 O-acetylation, which complicated the reaction mixture analysis. DMF at 50 °C was found to be the most suitable solvent for the isomerization and was used for further Lewis acid screening. Eventually, BF3·OEt2 proved
- the 10,11-cis-isomer with the 2R,3R configuration was not observed during/after the isomerization of 1a in EtOAc. All the reactions in EtOAc were accompanied by C-23 O-acetylation. Separation and purification of 2,3-cis-silybins The separation of 2,3-cis-silybin 7 from unreacted 2,3-trans-silybin 1a
- ], and at the preparatory scale by lipase-catalyzed discrimination [4][5]. However, chromatographic separation of 2,3-cis- and 2,3-trans-silybins is feasible after their C-23 O-acetylation, which can be accomplished with Novozym 435 in an acetone/vinyl acetate mixture, giving a nearly quantitative yield
Convergent synthesis of a tetrasaccharide repeating unit of the O-specific polysaccharide from the cell wall lipopolysaccharide of Azospirillum brasilense strain Sp7
Beilstein J. Org. Chem. 2014, 10, 293–299, doi:10.3762/bjoc.10.26
- reaction sequence consisting of 3,4-O-isopropylidenation with 2,2-dimethoxypropane in the presence of p-toluenesulfonic acid [37], conventional acetylation of the free hydroxy groups followed by acidic hydrolysis of the acetonide functionality. Selective acetylation of compound 7 by the formation of an
Synthesis of novel derivatives of 5-hydroxymethylcytosine and 5-formylcytosine as tools for epigenetics
Beilstein J. Org. Chem. 2014, 10, 7–11, doi:10.3762/bjoc.10.2
- -enzymes; Introduction Epigenetic modifications play a crucial role in cell differentiation and cell development [1]. They control gene expression through several mechanisms such as non-coding RNAs, histone modifications (acetylation, methylation, phosphorylation, etc.) [2], and DNA methylation [3][4][5
Synthesis and determination of the absolute configuration of (−)-(5R,6Z)-dendrolasin-5-acetate from the nudibranch Hypselodoris jacksoni
Beilstein J. Org. Chem. 2013, 9, 2925–2933, doi:10.3762/bjoc.9.329
- (+)-pallescensone. A synthetic sample ([α]D −8.7) of the new metabolite was prepared by [1,2]-Wittig rearrangement of a geranylfuryl ether followed by acetylation of purified alcohol isomers. The absolute configuration at C-5 was established as R by the analysis of MPA ester derivatives of (Z)-5-hydroxydendrolasin
- characterization of 1, in particular the configuration at C-5. The synthesis, which was completed in five steps, involved preparation of 3-furylmethanol (4) and of geranyl bromide (5), etherification, [1,2]-Wittig rearrangement of geranyl 3-furylmethyl ether (6) to produce 7a/b, and acetylation to obtain target 1
- five-step synthesis involving [1,2]-Wittig rearrangement of geranyl furyl ether (6) followed by acetylation of the purified alcohol products. The absolute configuration in 1 was established as 5R by detailed comparison with MPA ester derivatives prepared from individual enantiomers of synthetic (6Z)-5
The myxocoumarins A and B from Stigmatella aurantiaca strain MYX-030
Beilstein J. Org. Chem. 2013, 9, 2579–2585, doi:10.3762/bjoc.9.293
- intermediate, putatively phloroglucinol (12) [36]. Nitrophenol 13 likely constitutes a direct biosynthetic precursor of the myxocoumarins. Upon O-acetylation of 13 with the long-chain β-keto acid building block 14, putatively recruited from fatty-acid biosynthesis, the intermediate ester 15 could undergo C–C
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