An efficient synthesis of 1,6-anhydro-N-acetylmuramic acid from N-acetylglucosamine

• Matthew B. Calvert,
• Christoph Mayer and
• Alexander Titz

Beilstein J. Org. Chem. 2017, 13, 2631–2636, doi:10.3762/bjoc.13.261

• in only five steps from the cheap starting material N-acetylglucosamine. This efficient synthesis should enable future studies into the importance of 1,6-anhydromuramic acid in bacterial cell wall recycling processes. Keywords: N-acetylmuramic acid; anhydrosugars; antibiotic resistance; bacterial

• cell wall recycling; carbohydrate synthesis; Introduction 1,6-Anhydro-N-acetylmuramic acid (AnhydroMurNAc, 1, Figure 1) and its derivatives (e.g., 2 and 3) are of great interest due to their integral role in bacterial cell wall recycling [1][2] and the induction of antibacterial resistance [3

Syntheses, structures, and stabilities of aliphatic and aromatic fluorous iodine(I) and iodine(III) compounds: the role of iodine Lewis basicity

• Tathagata Mukherjee,
• Soumik Biswas,
• Andreas Ehnbom,
• Subrata K. Ghosh,
• Ibrahim El-Zoghbi,
• Nattamai Bhuvanesh,
• Hassan S. Bazzi and
• John A. Gladysz

Beilstein J. Org. Chem. 2017, 13, 2486–2501, doi:10.3762/bjoc.13.246

• abstraction is effected by a species other than the chlorine radical Cl·, presumably PhICl· [26][27]. One potential attraction of fluorous iodine(III) dichlorides as chlorinating agents would be the recovery and recycling of the fluorous iodide byproduct. Towards this end, higher fluorophilicities are usually

• the free radical chlorination of methane [25]. Under certain conditions, uncommon selectivities were apparent, but the fluorophilicities of the dichlorides or precursor iodides studied were insufficient for certain target recycling strategies. As discussed above, it is not clear how to meet these

Correction: Mechanochemical enzymatic resolution of N-benzylated-β³-amino esters

• Mario Pérez-Venegas,
• Gloria Reyes-Rangel,
• Adrián Neri,
• Jaime Escalante and
• Eusebio Juaristi

Beilstein J. Org. Chem. 2017, 13, 2128–2130, doi:10.3762/bjoc.13.210

• under ball milling. Substrate scope for the enzymatic resolution of N-benzylated-β3-amino esters. Recycling capacity of immobilized CALB under HSBM conditions. Scaling-up of the enzymatic hydrolysis reaction under ball-milling using substrate rac-1a. Supporting Information Supporting Information File

New bio-nanocomposites based on iron oxides and polysaccharides applied to oxidation and alkylation reactions

• Daily Rodríguez-Padrón,
• Alina M. Balu,
• Antonio A. Romero and
• Rafael Luque

Beilstein J. Org. Chem. 2017, 13, 1982–1993, doi:10.3762/bjoc.13.194

• have the additional advantage of easy recycling and reuse, which is an essential and desired property in many applications such as catalysis, sensors and even medicine [2][6][8][9]. Our research group has recently prepared different types of metal and metal oxide nanoparticles which have several

Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C–S cross-coupling reaction

• Debasish Sengupta,
• Koushik Bhowmik,
• Goutam De and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 1796–1806, doi:10.3762/bjoc.13.174

• purified by column chromatography over a short column of silica gel and eluting with light petroleum to obtain 0.85 g (92%) of pure (4-methoxyphenyl)(phenyl)sulfane as a colourless liquid. Recycling experiments of Ni/RGO-40 catalyst in C−S cross-coupling reaction between 4-iodoanisole and benzenethiol. (a

Mechanochemical enzymatic resolution of N-benzylated-β³-amino esters

• Mario Pérez-Venegas,
• Gloria Reyes-Rangel,
• Adrián Neri,
• Jaime Escalante and
• Eusebio Juaristi

Beilstein J. Org. Chem. 2017, 13, 1728–1734, doi:10.3762/bjoc.13.167

• -benzylated-β3-amino esters. Recycling capacity of immobilized CALB under HSBM conditions. Scaling-up of the enzymatic hydrolysis reaction under ball-milling using substrate rac-1a. Supporting Information Supporting Information File 254: Experimental section, NMR spectra, chromatograms and X-ray diffraction

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• of the coupled products with unacceptable Pd species led to a hard separation and recycling of homogeneous catalyst systems. In our previous study [4] we reported a ball-milling Heck reaction catalyzed by Pd(OAc)2. Although the catalyst showed the satisfactory reactivity, it was difficult to recover

• (1.5 mmol), K2CO3 (3.6 mmol), and 5 g silica gel were placed in a 80 mL stainless-steel vessel (ΦMB = 0.25, dMB = 5 mm). HSBM conditions: 60 min at 800 rpm. Recycling studies of the Pd/MgAl-LDH catalyst for Heck reactions. Reaction conditions: 1i or 1m (1.5 mmol), 2a (2.1 mmol), Pd/MgAl-LDHs (2.5 mol

Towards the development of continuous, organocatalytic, and stereoselective reactions in deep eutectic solvents

• Davide Brenna,
• Elisabetta Massolo,
• Alessandra Puglisi,
• Sergio Rossi,
• Giuseppe Celentano,
• Maurizio Benaglia and
• Vito Capriati

Beilstein J. Org. Chem. 2016, 12, 2620–2626, doi:10.3762/bjoc.12.258

• grams of crude aldol), that could be recovered by distillation and reused in new reactions (for experimental details on the product recovery, mass balance and 1H NMR spectra of the crude mixture see Supporting Information File 1). Finally, we also performed preliminary recycling experiments using two

The weight of flash chromatography: A tool to predict its mass intensity from thin-layer chromatography

• Freddy Pessel,
• Jacques Augé,
• Isabelle Billault and
• Marie-Christine Scherrmann

Beilstein J. Org. Chem. 2016, 12, 2351–2357, doi:10.3762/bjoc.12.228

• retention volumes and easy recycling offers an interesting alternative [26] but requires a significant investment. Chromatographic peak of a compound eluted at a retention volume VR with a width ω. Variation of with x for reaction b (Scheme 1). Comparison between calculated and experimental values of MIChr

Diels–Alder reactions in confined spaces: the influence of catalyst structure and the nature of active sites for the retro-Diels–Alder reaction

• Ángel Cantín,
• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2016, 12, 2181–2188, doi:10.3762/bjoc.12.208

• cyclopentadiene and p-benzoquinone in presence of Beta zeolites, the ability of reuse of Beta Si/Al = 50 was examined. As shown in Figure 7a,b the activity of the catalyst decreases in some extension after repeated recycling. As expected for a less active catalyst, conversion falls partly while the selectivity to

• the kinetically controlled endo-endo isomer rises after recycling. Conclusion In this work the DAR between cyclopentadiene and p-benzoquinone has been proved to take place on the catalyst surface when the reaction is carried out in presence of microporous materials, obtaining better results when a

Silica-supported sulfonic acids as recyclable catalyst for esterification of levulinic acid with stoichiometric amounts of alcohols

• Raimondo Maggi,
• N. Raveendran Shiju,
• Veronica Santacroce,
• Giovanni Maestri,
• Franca Bigi and
• Gadi Rothenberg

Beilstein J. Org. Chem. 2016, 12, 2173–2180, doi:10.3762/bjoc.12.207

• particular, issues with catalyst recycling and product separation limits the environmental viability of this strategy. As a result, it remains of high interest to develop alternatives to trigger this reaction, which are more sustainable, for instance through the design of suitable and recyclable solid acid

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• to facilitate work-up, recycling, and purification of products, especially for large-scale preparations. These heterogeneous systems include supported metal oxides and binary oxide mixtures. For example, MoO3/SiO2 and sol–gel MoO3/TiO2 is used for the preparation of diphenyl oxalate monomer (DPO

• similar processes [27][28]. Notably, the screening of the reaction variables includes not only the required reaction steps, but also the associated operations including separation and purification of products, recycling of solvents and catalysts, and waste treatments as well. All these additional steps

• to prepare by any other route. This protocol avoids the use of halides, and generates water as the only byproduct [33]. Synthesis of supported ionic liquids (SILs): Ionic liquids are far more expensive than classical solvents, with costs higher by a factor of 10-to-50. The recycling of the ILs is

Methylpalladium complexes with pyrimidine-functionalized N-heterocyclic carbene ligands

• Dirk Meyer and
• Thomas Strassner

Beilstein J. Org. Chem. 2016, 12, 1557–1565, doi:10.3762/bjoc.12.150

• group uses a mixture of trifluoroacetic acid (TFA) and its anhydride (TFAA) as solvents. It has the advantage that the formed ester can be separated and hydrolyzed, followed by recycling of the free acid which potentially can be reused in the process [24][25][26][27][28][29][30]. Contrary to the

Star-shaped and linear π-conjugated oligomers consisting of a tetrathienoanthracene core and multiple diketopyrrolopyrrole arms for organic solar cells

• Hideaki Komiyama,
• Chihaya Adachi and
• Takuma Yasuda

Beilstein J. Org. Chem. 2016, 12, 1459–1466, doi:10.3762/bjoc.12.142

• provide TTA-DPP4 as a dark purple solid. This compound was further purified by recycling preparative gel permeation chromatography (GPC; eluent: chloroform) prior to use (yield = 0.36 g, 44%). MS (MALDI–TOF) m/z: [M]+ calcd for 3133.42; found 3133.51; anal. calcd (%) for C190H226N8O8S12: C, 72.80; H, 7.27

Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• enantioselective carbenoid insertion into C(sp3)–H bond/Cope rearrangement. The reactions afforded good yields and excellent enantioselectivity. The recycling of the catalyst was evaluated in a cyclopropanation reaction and no significant decrease on its performance could be observed after five runs. Conclusion

Highly stable and reusable immobilized formate dehydrogenases: Promising biocatalysts for in situ regeneration of NADH

• Barış Binay,
• Dilek Alagöz,
• Deniz Yildirim,
• Ayhan Çelik and
• S. Seyhan Tükel

Beilstein J. Org. Chem. 2016, 12, 271–277, doi:10.3762/bjoc.12.29

• [14] and lack of reusability, therefore, the immobilization of FDH has been of increasing interest in the recent years. For example, Netto et al. [15] immobilized FDH from Candida boidinii on three different magnetic supports and the results showed that conversion rates and recycling values were

Biocatalysis for the application of CO₂ as a chemical feedstock

• Apostolos Alissandratos and
• Christopher J. Easton

Beilstein J. Org. Chem. 2015, 11, 2370–2387, doi:10.3762/bjoc.11.259

• ], where an exchange between 14CO2 and formate was observed, though no net synthesis of formate. Thauer [114] was the first to observe a net CO2 reduction to formate for the acetogenic FDH by recycling of the reduced cofactor, and prove that this enzyme utilised NADPH for the reduction of CO2 as the first

• display higher reduction activities than FDHs of lower homology. The possibility of recycling the reduced electron donating cofactor, through the action of a second enzyme such as hydrogenase, or through direct or mediated electron delivery from an electrode, greatly enhance the potential of FDHs for

The Beilstein Journal of Organic Chemistry and the changing face of scientific publishing

• Martin G. Hicks and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2015, 11, 2242–2244, doi:10.3762/bjoc.11.242

• databases with inherent differences in precision and recall, as well as scientific social media [18], provide good substitutes for traditional browsing. The problems of plagiarism and self-plagiarism (also known as recycling) [19] are becoming more transparent thanks to open access and the CrossCheck system

• for plagiarism, in particular when often around 20% of submitted manuscripts are rejected based on detected content similarity. Scientific research and the reporting of the results are based on trust. Plagiarism and recycling are seriously diluting the quality of science and are a significant waste of

Molecular-oxygen-promoted Cu-catalyzed oxidative direct amidation of nonactivated carboxylic acids with azoles

• Wen Ding,
• Shaoyu Mai and
• Qiuling Song

Beilstein J. Org. Chem. 2015, 11, 2158–2165, doi:10.3762/bjoc.11.233

• into the desired 3 via intermediate D along with the recycling of the Cu catalyst. Conclusion In conclusion, Cu-catalyzed oxidative direct amidation from nonactivated carboxylic acid with benzimidazoles under dioxygen atmosphere with molecular oxygen as an activating reagent has been described. Azole

Computational study of productive and non-productive cycles in fluoroalkene metathesis

• Markéta Rybáčková,
• Jan Hošek,
• Ondřej Šimůnek,
• Viola Kolaříková and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2015, 11, 2150–2157, doi:10.3762/bjoc.11.232

• only return back to complex MC. It should be noted that the main aim of the development of the family of Hoveyda–Grubbs catalysts was the recycling of the catalyst. This implies a successful release-return mechanism, in which after a successful metathesis the active complexes AC or MC react with 2

Olefin metathesis in air

• Lorenzo Piola,
• Fady Nahra and
• Steven P. Nolan

Beilstein J. Org. Chem. 2015, 11, 2038–2056, doi:10.3762/bjoc.11.221

• the Ru moiety. Decomplexation of the latter allowed the approach of the olefinic substrate. Once the reaction reached completion and the starting materials depleted, the isopropoxy group coordinated back to the Ru center, allowing for the recycling of the catalyst. However, it should be mentioned that

• 0.01 mol % catalyst loading. Later in the same year, Olszewski, Skowerski et al. reported the synthesis and use of new Scorpio-type complexes (Figure 10) [69]. These complexes presented high affinity for silica, which allowed the easy separation and recycling of the catalysts from the reaction mixture

Engineering Pichia pastoris for improved NADH regeneration: A novel chassis strain for whole-cell catalysis

• Martina Geier,
• Christoph Brandner,
• Gernot A. Strohmeier,
• Mélanie Hall,
• Franz S. Hartner and
• Anton Glieder

Beilstein J. Org. Chem. 2015, 11, 1741–1748, doi:10.3762/bjoc.11.190

• bottleneck for an efficient cofactor recycling via the dissimilatory pathway, significantly improved the production rates of NADH-dependent whole-cell biotransformations. In contrast, the present study focuses on redirecting the flux in the MUT pathway by disrupting the assimilation pathway. Thus, the co

• transformants and the FLP recombinase system [21] to enable marker recycling. Thereby, marker-free knock-out strains were obtained which only have one 34 bp FLP recombination target sequence (FRT) left in the targeted locus. The cassettes were designed such that the complete coding sequence including the start

• cassette, reaching ~35% and ~8% substrate conversion, respectively. As for the recombinant strains, two products were detected, namely (2R,3R)-butane-2,3-diol and meso-butane-2,3-diol. Conclusion Efficient cofactor recycling is not only required for an optimal enzyme performance, but is also crucial to

Grubbs–Hoveyda type catalysts bearing a dicationic N-heterocyclic carbene for biphasic olefin metathesis reactions in ionic liquids

• Maximilian Koy,
• Hagen J. Altmann,
• Benjamin Autenrieth,
• Wolfgang Frey and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 1632–1638, doi:10.3762/bjoc.11.178

• solvent (toluene) and the ionic liquid (IL) 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [BDMIM+][BF4−]. The structure of Ru-2 was confirmed by single crystal X-ray analysis. Keywords: biphasic catalysis; ionic initiators; recycling; ROMP; ruthenium; Introduction Ionic metathesis catalysts offer

• utmost interest. Recycling experiments carried out with M1 revealed that with the aid of 2-(2-PrO)-styrene, Ru-2 could be used in three consecutive cycles (Scheme 2). Over these three cycles, the number-average molecular weight, Mn, significantly decreased while PDIs increased from 2.1 to 3.0. Again, Ru

• cooling to room temperature, ethyl vinyl ether (1 mL) was added and the reaction mixture was allowed to stir for another 30 min. Finally, the reaction mixture was poured into methanol. The polymer was obtained as a white or off-white solid. General ROMP-procedure with recycling: Ru-2 (11.1 mg, 10 µmol

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

• Yuri A. Rulev,
• Zalina Gugkaeva,
• Victor I. Maleev,
• Michael North and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2015, 11, 1614–1623, doi:10.3762/bjoc.11.176

• free conditions. Catalyst recycling experiments are also reported and show the robustness of this system. Results and Discussion The preparation of salen ligands 8a and 8b was conducted according to Scheme 2, starting from tert-butylphenol, which was formylated and then nitrated to produce 5-nitro-3

Synthesis of racemic and chiral BEDT-TTF derivatives possessing hydroxy groups and their achiral and chiral charge transfer complexes

• Sara J. Krivickas,
• Chiho Hashimoto,
• Junya Yoshida,
• Akira Ueda,
• Kazuyuki Takahashi,
• John D. Wallis and
• Hatsumi Mori

Beilstein J. Org. Chem. 2015, 11, 1561–1569, doi:10.3762/bjoc.11.172

• of enatiopure donors 1 and the preparations of their charge transfer complexes are under way. Moreover, enantiopure (S,S)-2 and (R,R)-2 were also synthesized as shown in Scheme 2. Chiral HPLC was performed using a JAIGEL-OA7500 column on a JAI LC-908 recycling preparative system using the solvent