The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• linked with a central pyrimidine core and another one is linked by a rigid thiophene cycle as a π-conjugated bridge. We have applied a usual synthetic protocol which includes eight successive steps: O-alkylation of 4-methoxyphenol (1), N-alkylation of carbazole (2), formylation or acetylation of a

• -carbazoles 3a,b were obtained via acetylation of the same carbazoles 1a,b [20]. The presence of an acetyl group in the resulted compounds 3a and 3b gives the opportunity to extend their conjugation chain via incorporation of an thiophene moiety with the help of a Vilsmeier–Haack–Arnold reaction. The reaction

Synthesis of oligonucleotides on a soluble support

• Harri Lönnberg

Beilstein J. Org. Chem. 2017, 13, 1368–1387, doi:10.3762/bjoc.13.134

• by acetylation and the support was again precipitated with Et2O. Finally, ammonolysis was carried out and the oligonucleotide was separated from the PEG support by precipitation from MeOH. The feasibility of the method was tested by the synthesis of d(5´-ACGGGCCCGT-3´) in 75% yield. Synthesis of

One-pot synthesis of block-copolyrotaxanes through controlled rotaxa-polymerization

• Jessica Hilschmann,
• Gerhard Wenz and
• Gergely Kali

Beilstein J. Org. Chem. 2017, 13, 1310–1315, doi:10.3762/bjoc.13.127

• Supporting Information File 1). The molar masses of polyrotaxanes 1 and 2 were determined after complete acetylation by GPC in THF (for results see Table 1). From the molar ratio i/st, the average molar mass per monomer repeat was derived Da for both polyrotaxanes 1 and 2, which allows to calculate the

• polyrotaxanes 3–6 were determined after complete acetylation by GPC in THF (Table 2). First, after homopolymerization, the molar masses were 9 and 4 kDa for the polyHEMA and polyTRIS-AAm stoppers blocks, respectively. After block copolymerization with isoprene complexed in RAMEB, the corresponding molar masses

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

An eco-compatible strategy for the diversity-oriented synthesis of macrocycles exploiting carbohydrate-derived building blocks

• Sushil K. Maurya and
• Rohit Rana

Beilstein J. Org. Chem. 2017, 13, 1106–1118, doi:10.3762/bjoc.13.110

• , eco-friendly without compromise in yield and selectivity. Build-couple-pair (B/C/P) strategy for macrocycles. Different building blocks used for DOS. Cycloaddition reaction of alkyne-azide building block. Acetylation of macrocycle 4m. Optimization of the reaction conditions for the cycloaddition

A concise and practical stereoselective synthesis of ipragliflozin L-proline

• Shuai Ma,
• Zhenren Liu,
• Jing Pan,
• Shunli Zhang and
• Weicheng Zhou

Beilstein J. Org. Chem. 2017, 13, 1064–1070, doi:10.3762/bjoc.13.105

• -selectivity [9][10]. This approach included six steps such as addition, methyl etherification, acetylation, reduction, deprotection and cocrystallization with L-proline to get 1 with a total yield of 32.89%. The subsequent improvement reported included the replacement of aryllithium by aryl Grignard reagents

Total synthesis of TMG-chitotriomycin based on an automated electrochemical assembly of a disaccharide building block

• Yuta Isoda,
• Norihiko Sasaki,
• Kei Kitamura,
• Shuji Takahashi,
• Sujit Manmode,
• Naoko Takeda-Okuda,
• Jun-ichi Tamura,
• Toshiki Nokami and
• Toshiyuki Itoh

Beilstein J. Org. Chem. 2017, 13, 919–924, doi:10.3762/bjoc.13.93

• were achieved by following the procedure reported by Yu and co-workers (Figure 4) [8]. Phthaloyl groups and acetyl groups of 7 are removed by the reaction with ethylenediamine followed by applying the conventional acetylation protocol with acetic anhydride (Ac2O) in the presence of N,N

Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties

• Işıl Yenice,
• Sinan Basceken and
• Metin Balci

Beilstein J. Org. Chem. 2017, 13, 825–834, doi:10.3762/bjoc.13.83

• starting compound 8 was synthesized via a slightly modified route by acetylation of pyrrole with trichloroacetyl chloride in 89% yield [19][23]. The reaction of 8 with NaOMe in methanol gave pyrrole ester 9 (Scheme 1) [19][24]. It is essential to use bromoalkynes for N-alkyne substitution of pyrrole ester

• aromatic o-carbon atoms at 128.8 ppm indicating the structure 13c. For further proof of the structure, 12c was submitted to an acetylation reaction with acetic anhydride in pyridine to give the acetylated compound 14 in 97% yield (Scheme 2). The NH- proton resonance was now shifted to lower field (9.12 ppm

• energies shown for 20, TS1, and 21). Synthesis of N-alkyne substituted methyl 1H-pyrrole-2-carboxylate derivatives 7a–d. Nucleophilic cyclization reaction of compounds 7a–d and acetylation of 12c. Synthesis of 16. Proposed reaction mechanism of nucleophilic cyclization reaction of 7. Electrophilic

Synthesis of D-manno-heptulose via a cascade aldol/hemiketalization reaction

• Yan Chen,
• Xiaoman Wang,
• Junchang Wang and
• You Yang

Beilstein J. Org. Chem. 2017, 13, 795–799, doi:10.3762/bjoc.13.79

• to synthesize the 2-OH-protected C4 aldehyde for the assembly of the seven-carbon skeleton. Thus, acetylation of the 2-OH group in 7 with acetic anhydride and DMAP in dichloromethane provided ester 8 in 86% yield. The positions of the 2-acetyl and 3-PMB groups were determined by 1H, 13C and 2D NMR

• -hydroxy group in 14 followed by treatment with DDQ could yield the desired 5-hydroxy product in high yield. Indeed, acetylation of alcohol 14 with acetic anhydride delivered ester 15 in 91% yield. Removal of the PMB group in 15 with DDQ resulted in a very clean reaction, affording alcohol 16 in an

NMR reaction monitoring in flow synthesis

• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2017, 13, 285–300, doi:10.3762/bjoc.13.31

• experimental setup of the flow system. (a) Microfluidic probe. (b) Microreactor holder. (c) Stripline NMR chip holder. (d) Arrangement of the microfluidic chip in the holder. Reproduced with permission from reference [44]. Copyright 2009 The American Chemical Society. Acetylation of benzyl alcohol. Spectra at

Total synthesis of a Streptococcus pneumoniae serotype 12F CPS repeating unit hexasaccharide

• Peter H. Seeberger,
• Claney L. Pereira and
• Subramanian Govindan

Beilstein J. Org. Chem. 2017, 13, 164–173, doi:10.3762/bjoc.13.19

• steps from known galactosylazide selenide 23 [29]. Acetylation of the C3 hydroxy group of 23 furnished fully differentially protected selenoglycoside 24 in 82% yield. Hydrolysis of the selenoglycoside using NIS in aqueous THF produced hemiacetal 25 that was silylated prior to selective saponification of

O-Alkylated heavy atom carbohydrate probes for protein X-ray crystallography: Studies towards the synthesis of methyl 2-O-methyl-L-selenofucopyranoside

• Roman Sommer,
• Dirk Hauck,
• Annabelle Varrot,
• Anne Imberty,
• Markus Künzler and
• Alexander Titz

Beilstein J. Org. Chem. 2016, 12, 2828–2833, doi:10.3762/bjoc.12.282

• sodium acetate as base. From this acetylation reaction, a chromatographically inseparable mixture of isomeric per-O-acetylated pyranosides 9α/9β and a single furanoside 10 in a ratio of 9α/9β/10 = 3:1:3 was obtained in 42% yield over the two steps (Scheme 2). The isomeric mixture of acetates was then

• benzyl ether protecting group in O-2 position [42]. By varying the reaction conditions during the acetylation step, the authors were able to reduce the formation of furanoses but complete suppression was not achieved. Therefore, our strategy was to block the hydroxy group in position 4 and, thus, to

• cleavage and in situ acetylation resulted in the pyranose mixture 9αβ with excellent yield (90%, 9α/9β = 4:1) and prevention of unwanted furanoside side products. The seleno moiety was then introduced as described before and 13αβ (13α/13β = 1:3) was obtained in 78% yield. Further Lewis acid catalyzed

Useful access to enantiomerically pure protected inositols from carbohydrates: the aldohexos-5-uloses route

• Felicia D’Andrea,
• Giorgio Catelani,
• Lorenzo Guazzelli and
• Venerando Pistarà

Beilstein J. Org. Chem. 2016, 12, 2343–2350, doi:10.3762/bjoc.12.227

• good agreement with what has been reported before on similar compounds [45]. The structure and stereochemistry of inositols 13–19 were confirmed by 1H, 13C and 2D NMR experiments directly or after per-acetylation of the reduction product and/or through comparison with previously reported compounds

Tunable microwave-assisted method for the solvent-free and catalyst-free peracetylation of natural products

• Manuela Oliverio,
• Paola Costanzo,
• Monica Nardi,
• Carla Calandruccio,
• Raffaele Salerno and
• Antonio Procopio

Beilstein J. Org. Chem. 2016, 12, 2222–2233, doi:10.3762/bjoc.12.214

• green acetylation of hydrophilic biological molecules, potentially easily scalable for industrial applications, including pharmaceutical, cosmetic and food industry. Keywords: catalyst-free; microwaves; peracetylation; polyhydroxylated compounds; solvent-free; Introduction Peracetylation of alcohols

• hydroxy groups are unstable in neutral, slight alkaline or oxidative environments [4]. Furthermore, acetylation is a chemical modification well accepted in a biological environment, being the N-acetylation, N,O-acyl transfer and the deacetylation some of the metabolic processes mediated by cytosolic and

• heterogeneous or supported catalysts [15][16][17], solid nanopowders or nanoparticles [18][19], non-metal-based heterogeneous acetylation catalysts [20][21][22], as well as natural marine clays instead of homogeneous catalysts as reaction activators [23]. Even if these methods allow a complete peracetylation of

Solvent-free synthesis of novel para-menthane-3,8-diol ester derivatives from citronellal using a polymer-supported scandium triflate catalyst

• Lubabalo Mafu,
• Ben Zeelie and
• Paul Watts

Beilstein J. Org. Chem. 2016, 12, 2046–2054, doi:10.3762/bjoc.12.193

• complex reaction mixtures. When considering the diester selectivity (Figure 2), a rapid acetylation of the secondary hydroxy group is evident at short reaction times and lower reaction temperatures between 50 and 60 °C [12]. Further increase in the reaction time leads to the acetylation of the less

• an acetylation reaction with 2:1 molar ratio, the reaction affords the same results as when excess anhydride 5 is used. Moreover, the minimum use of the acetylating reagent helps to reduce the formation of carboxylic acid as the by-product. As a consequence, a more cost-effective and environmentally

Synthesis of the C8’-epimeric thymine pyranosyl amino acid core of amipurimycin

• Pramod R. Markad,
• Navanath Kumbhar and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2016, 12, 1765–1771, doi:10.3762/bjoc.12.165

• ester 15. Acetylation of 15 with acetic anhydride in pyridine gave acetate derivative 16 in 95% yield. Having fully functionalized intermediate 16 in hand, we thought to incorporate the purine nucleobase using Vorbrüggen conditions. Thus, reaction of glycosyl donor 16 with bis(trimethylsilyl)-2-(N

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

• Franziska Hemmerling and
• Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

• agglomerin A (147) biosynthesis proceeds as a two-step process [143]. An initial acyl transferase Agg4-catalysed acetylation of the primary hydroxy group in 158 is followed by dehydratase Agg5-catalysed acetic acid elimination, leading to olefin 147 (Scheme 22). This mechanism was confirmed by gene knockout

• analogous acetylation–elimination process was experimentally confirmed for quartromicin D1 (151) biosynthesis (Scheme 22) [145]. VstJ has been identified as a probable candidate for the enzyme-catalysed [4 + 2] cycloaddition in versipelostatin A (153) biosynthesis by heterologous expression, gene knockout

Synthesis of 2-substituted tetraphenylenes via transition-metal-catalyzed derivatization of tetraphenylene

• Shulei Pan,
• Hang Jiang,
• Yanghui Zhang,
• Yu Zhang and
• Dushen Chen

Beilstein J. Org. Chem. 2016, 12, 1302–1308, doi:10.3762/bjoc.12.122

• substituted ones. Although direct bromination [22], nitration [22], and acetylation [45] of tetraphenylene via electrophilic aromatic substitution have been reported, it is still desirable to develop new methods for the derivatization of tetraphenylenes. Herein we report several synthetic protocols for the

Reactions of N,3-diarylpropiolamides with arenes under superelectrophilic activation: synthesis of 4,4-diaryl-3,4-dihydroquinolin-2(1H)-ones and their derivatives

• Larisa Yu. Gurskaya,
• Diana S. Belyanskaya,
• Dmitry S. Ryabukhin,
• Denis I. Nilov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 950–956, doi:10.3762/bjoc.12.93

• -acetylation reactions were carried out. Compounds 2a,d,e and h were N-formylated in the system POCl3–DMF–CHCl3 under the Vilsmeier–Haack reaction conditions with formation of compounds 5a–d (Scheme 2). Apart from that, dihydroquinolinones 2a,e–h were acetylated into derivatives 6a–e (Scheme 2). Then reactions

Muraymycin nucleoside-peptide antibiotics: uridine-derived natural products as lead structures for the development of novel antibacterial agents

• Daniel Wiegmann,
• Stefan Koppermann,
• Marius Wirth,
• Giuliana Niro,
• Kristin Leyerer and
• Christian Ducho

Beilstein J. Org. Chem. 2016, 12, 769–795, doi:10.3762/bjoc.12.77

• . Acetylation of the thus formed primary alcohol resulted in compound 38. This was followed by benzyl and Cbz deprotection and the subsequent urea formation with the imidazolium salt 39 to furnish tripeptide 40. After Boc deprotection, the resultant amine was guanidinylated using isothiourea 41. The thus

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

• in terms of product purity. Hydrogenolysis of 42 on palladium in ethanol/HCl followed by acetylation of the amino group furnished the target acetylated 3-fluoro-D-GlcNAc 5 as a chromatographically separable mixture of anomers (Table 1). Addition of HCl was found necessary to effect a clean

Elucidation of a masked repeating structure of the O-specific polysaccharide of the halotolerant soil bacteria Azospirillum halopraeferens Au4

• Elena N. Sigida,
• Yuliya P. Fedonenko,
• Alexander S. Shashkov,
• Nikolay P. Arbatsky,
• Evelina L. Zdorovenko,
• Svetlana A. Konnova,
• Vladimir V. Ignatov and
• Yuriy A. Knirel

Beilstein J. Org. Chem. 2016, 12, 636–642, doi:10.3762/bjoc.12.62

• -methylglucose, 2,4-di-O-methylrhamnose, 2,4-di-O-methylfucose, 2-O-methylfucose, and 3,4-di-O-methylxylose were identified by GLC–MS of partially methylated alditol acetates derived after methylation of the OPS with MeI followed by hydrolysis and acetylation [14]. Therefore, the OPS contains 3-substituted Rha

• afforded complementary oligosaccharides, which identification shed light on the nature of the OPS irregularity and, combined with chemical analysis and NMR spectroscopic analysis data, enabled the structure elucidation of the OPS. Chemical modifications of the OPS, such as O-methylation or O-acetylation

• -stoichiometric substituents in the OPS has been reported for phytopathogens Pseudomonas syringae [29] and Xanthomonas campestris [30] as well as for beneficial rhizobacteria, including free-living Azospirillum spp. [31][32][33][34][35] and root-nodulating Rhizobium spp. [24]. Moreover, the degree of acetylation

Regiodefined synthesis of brominated hydroxyanthraquinones related to proisocrinins

• Joyeeta Roy,
• Tanushree Mal,
• Supriti Jana and
• Dipakranjan Mal

Beilstein J. Org. Chem. 2016, 12, 531–536, doi:10.3762/bjoc.12.52

• lactol 34 with methylmagnesium bromide afforded diol 35 in 72% yield. Selective oxidation of the allylic alcohol group in 35 with MnO2, followed by acetylation of the secondary hydroxy group with acetyl chloride, triethylamine and DMAP furnished cyclohexenone 36 (Scheme 5). The Hauser annulation of

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

• commercial p-hydroxyphenylcarbaldehydes 4a–c which are less expensive than the corresponding p-hydroxybenzyl alcohols (Scheme 1). The conventional acetylation of 4a–c with acetic anhydride in pyridine gave p-acetoxyphenylcarbaldehydes 5a–c in more than 98% yields. Subsequently the aldehyde function was

• corresponding alcohols, tyrosol and coniferyl alcohol. Therefore p-O-acetylated tyrosol (9) and p-O-acetylated coniferyl alcohol (12) were prepared from acids 7 and 10 by a two-step sequence: acid-catalysed acetylation of the phenolic hydroxy group (isolated yields >94%) followed by the reduction of the