A³-Coupling catalyzed by robust Au nanoparticles covalently bonded to HS-functionalized cellulose nanocrystalline films

• Jian-Lin Huang,
• Derek G. Gray and
• Chao-Jun Li

Beilstein J. Org. Chem. 2013, 9, 1388–1396, doi:10.3762/bjoc.9.155

• yields (Table 2, entries 1–8). However, long chain aldehydes had a lower activity, giving lower yields (Table 1, entries 9, 10). We also observed good to moderate yields when the cyclic dialkylamines such as pyrrolidine, morpholine and azepane were used (Table 2, entries 11–19). Catalyst recycling In

• order to determine the recycling ability of the catalysts, the following experiments were conducted. After completion of the reaction, the mixture was diluted with 0.5 mL deuterated chloroform (CDCl3) and filtered, and then the solid Au@HS-CNC(4.4 mol %) catalyst was washed 3 times with CDCl3, dried in

• -NCC and Au@HS-CNC (4.4 mol %) catalyst (scale bar: 5 nm). Thermogravimetric behavior of the Au@HS-CNC (4.4 mol %) catalyst (A) and CNC (B). FT-IR spectra of CNC, HS-CNC, and Au@HS-CNC (4.4 mol %) catalyst. Solid-state 13C NMR spectra of the CNC and Au@HS-CNC (4.4 mol %) catalyst. Recycling test of Au

Preparation of optically active bicyclodihydrosiloles by a radical cascade reaction

• Koichiro Miyazaki,
• Yu Yamane,
• Ryuichiro Yo,
• Hidemitsu Uno and
• Akio Kamimura

Beilstein J. Org. Chem. 2013, 9, 1326–1332, doi:10.3762/bjoc.9.149

• trans-2a/cis-2a ratio was determined to be 84/16. Careful separation of these two diastereomers gave pure trans-2a and minor isomers that contained cis-2a and 3 in a 74/26 ratio. The separation of 3 was achieved using a recycling GPC apparatus, giving pure 3 in 5% yield (5.1 mg, 0.011 mmol). (2S,3S

C–C Bond formation catalyzed by natural gelatin and collagen proteins

• Dennis Kühbeck,
• Basab Bijayi Dhar,
• Eva-Maria Schön,
• Carlos Cativiela,
• Vicente Gotor-Fernández and
• David Díaz Díaz

Beilstein J. Org. Chem. 2013, 9, 1111–1118, doi:10.3762/bjoc.9.123

• analysis of the reaction mixtures were in agreement with those reported in the literature (see Supporting Information File 1). Recycling experiments In general, acetone or ethanol (1 mL per 2 mg of catalyst) could be used to precipitate all of the gelatin catalyst, which could be further separated by

• no role in the product yield. Typical recycling experiments for the gelatin-catalyzed Henry reaction. Reaction conditions: 4-Nitrobenzaldehyde (1a, 15.1 mg, 0.1 mmol), nitromethane (2a, 27 μL, 0.5 mmol), solvent (0.5 mL), PSTA gelatin (2 mg), 37 °C, 6 h. Yields correspond to 1H NMR values obtained

Camera-enabled techniques for organic synthesis

• Steven V. Ley,
• Richard J. Ingham,
• Matthew O’Brien and
• Duncan L. Browne

Beilstein J. Org. Chem. 2013, 9, 1051–1072, doi:10.3762/bjoc.9.118

• sharing and recycling code and applications. Another important aspect of software libraries such as these is that whilst they use highly efficient C or C++ code to perform processor-intensive calculations, the “bindings” allow their full functionality to be harnessed by using languages such as Python

Iron-containing mesoporous aluminosilicate catalyzed direct alkenylation of phenols: Facile synthesis of 1,1-diarylalkenes

• Satyajit Haldar and
• Subratanath Koner

Beilstein J. Org. Chem. 2013, 9, 49–55, doi:10.3762/bjoc.9.6

• advantageous aspect of this type of solid-support catalyst is their scope for recycling. The reaction between phenol and phenylacetylene under optimized conditions was chosen to evaluate the recyclability of Fe-Al-MCM-41. The catalyst was separated after the completion of the reaction by simple centrifugation

• catalystsa. Reactions of arenes with phenylalkynesa. Recycling of Fe-Al-MCM-41 catalyst for the reaction of phenol with phenylacetylene. Supporting Information Supporting Information File 18: Experimental procedures with characterization data for all compounds. Acknowledgements S.H. thanks CSIR, New Delhi

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• product and recycling of the solution. A gas-liquid slug flow was also recently used for the [2 + 2] cycloaddition of a chiral cyclohexenone 89 with ethylene (Scheme 30) [83]. The reactor comprised of FEP tubing (1.0 mm i.d.) wrapped around a quartz immersion well with nine windings. The reaction was

Recyclable fluorous cinchona alkaloid ester as a chiral promoter for asymmetric fluorination of β-ketoesters

• Wen-Bin Yi,
• Xin Huang,
• Zijuan Zhang,
• Dian-Rong Zhu,
• Chun Cai and
• Wei Zhang

Beilstein J. Org. Chem. 2012, 8, 1233–1240, doi:10.3762/bjoc.8.138

• ]. Results and Discussion Cinchona alkaloids and their derivatives have been well-explored in asymmetric synthesis [28]. We envisioned that the introduction of a fluorous tag could facilitate the recycling of cinchona alkaloids. The synthesis of fluorous quinine ester C-1 was accomplished by the reaction of

• was also found that lowering of the reaction temperature from 25 to 10 or 0 °C did not necessarily improve the enantioselectivity of the fluorination (Table 1, entries 16 and 17). Recycling of promoter C-1 is an important part of this project. In our previous work we have demonstrated that fluorous

• for recycling of C-1 The reaction mixture was loaded onto a fluorous silica-gel cartridge (5 g) and eluted by 80:20 MeOH/H2O to collect nonfluorous components, including the fluorinated product. The cartridge was eluted with MeOH to collect C-1. After concentration of the MeOH fraction and drying at

Combined bead polymerization and Cinchona organocatalyst immobilization by thiol–ene addition

• Kim A. Fredriksen,
• Tor E. Kristensen and
• Tore Hansen

Beilstein J. Org. Chem. 2012, 8, 1126–1133, doi:10.3762/bjoc.8.125

• ; Introduction Polymer-supported chiral organocatalysts have emerged as a rapidly expanding field of research in recent years [1], in part due to the traditionally emphasized advantages of polymeric immobilization (facilitated separation and recovery procedures, recycling etc.), but perhaps even more due to the

• also tested in the Michael addition of methyl malonate to trans-β-nitrostyrene (Table 4) [21]. The catalyst gave quantitative yield and excellent enantioselectivity after 3–4 days reaction time. However, the catalyst exhibited poor recycling properties as yields fell sharply after the second reaction

• cycle; but selectivity remained largely untouched. At this point, we suspected that loss of the catalytic entities from the polymer resin may explain this, and indeed, CHN analysis of polymer resins after recycling verified that a loss of nitrogen content, meaning leaching of the active species, had

Discovery of practical production processes for arylsulfur pentafluorides and their higher homologues, bis- and tris(sulfur pentafluorides): Beginning of a new era of “super-trifluoromethyl” arene chemistry and its industry

• Teruo Umemoto,
• Lloyd M. Garrick and
• Norimichi Saito

Beilstein J. Org. Chem. 2012, 8, 461–471, doi:10.3762/bjoc.8.53

• industrial processes due to its ease in transfer, recovery and recycling. 2a satisfactorily reacted with HF at less than its boiling point to produce 3a along with the evolution of hydrogen chloride (Scheme 6). As seen in Table 5, this method has successfully been applied to various substituted arylsulfur

Reduction of benzylic alcohols and α-hydroxycarbonyl compounds by hydriodic acid in a biphasic reaction medium

• Michael Dobmeier,
• Josef M. Herrmann,
• Dieter Lenoir and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 330–336, doi:10.3762/bjoc.8.36

• (7) [M]+∙. Mechanism of the alcohol reduction and recycling of iodine. Reduction of benzylic alcohols to the corresponding alkanes. Alcohols showing incomplete or unselective reaction with hydriodic acid and red phosphorous (3.0 equiv HI, 0.4 equiv Pred). Alcohols yielding alkyl iodides with

Ion-exchange-resin-catalyzed adamantylation of phenol derivatives with adamantanols: Developing a clean process for synthesis of 2-(1-adamantyl)-4-bromophenol, a key intermediate of adapalene

• Nan Wang,
• Ronghua Wang,
• Xia Shi and
• Gang Zou

Beilstein J. Org. Chem. 2012, 8, 227–233, doi:10.3762/bjoc.8.23

• addition of a slight excess of acetic anhydride during the work-up procedure, making the process waste-free except for regeneration of the ion-exchange resin, and facilitating the recycling of the resin catalyst. The ion-exchange sulfonic acid resin catalyst could be readily recycled by filtration and

• directly reused at least ten times without a significant loss of activity. The key intermediate of adapalene, 2-(1-adamantyl)-4-bromophenol, could be produced by means of this waste-free process. Keywords: adamantylation; ion-exchange resin; phenol; recycling; Introduction o-Adamantylphenols and their

• recovered resin by drying the resin under vacuum (<0.5 mmHg) at 90 °C for 3 h before reuse, otherwise the reaction could not be carried to completion even after heating under reflux for 24 h (Table 1, entries 5–7). To facilitate recycling of the resin catalyst, we tested the reaction in ethanol, which was

The application of a monolithic triphenylphosphine reagent for conducting Appel reactions in flow microreactors

• Kimberley A. Roper,
• Heiko Lange,
• Anastasios Polyzos,
• Malcolm B. Berry,
• Ian R. Baxendale and
• Steven V. Ley

Beilstein J. Org. Chem. 2011, 7, 1648–1655, doi:10.3762/bjoc.7.194

• unsuccessful. Scavenging the dodecanol in the loading process by means of a column of polymer-supported tosyl chloride or by adding calcium chloride to the recycling carbon tetrabromide solution was also unsuccessful. Although the presence of dodecanol caused a partially depleted monolith during the loading

• monolith was placed in-line with the unloaded triphenylphosphine monolith in the recycling procedure with carbon tetrabromide. Bromination reactions in flow with the loaded triphenylphosphine monolith With the functionalised, active brominating monolith in hand, the transformation of an alcohol into the

• complete conversion it was found to be necessary to recycle the flow stream through the monolith. When a recycling protocol was employed, upon full consumption of the starting material by thin-layer chromatography the input was changed to a fresh solution of dichloromethane. The system was then flushed for

Continuous-flow enantioselective α-aminoxylation of aldehydes catalyzed by a polystyrene-immobilized hydroxyproline

• Xacobe C. Cambeiro,
• Rafael Martín-Rapún,
• Pedro O. Miranda,
• Sonia Sayalero,
• Esther Alza,
• Patricia Llanes and
• Miquel A. Pericàs

Beilstein J. Org. Chem. 2011, 7, 1486–1493, doi:10.3762/bjoc.7.172

• limitation is the development of reusable immobilized catalysts, thus allowing important reductions of the “effective” catalyst loading (through recycling and repeated use). Different approaches have been used for the development of immobilized analogs of proline and other organic catalysts. Among them, a

Coupled chemo(enzymatic) reactions in continuous flow

• Ruslan Yuryev,
• Simon Strompen and
• Andreas Liese

Beilstein J. Org. Chem. 2011, 7, 1449–1467, doi:10.3762/bjoc.7.169

• reactor to maintain the pH. The production facility also included an in-line product-separation unit consisting of a continuously operated counter-current extraction unit, and an online distillation unit for recycling of the organic solvent. The reaction product (2R,5R)-67 was obtained at a space time

Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

• M. Isabel Burguete,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2011, 7, 1347–1359, doi:10.3762/bjoc.7.159

• and the recycling of the IL phase containing the catalyst [44]. The IL–scCO2 system shows a specific phase behavior where CO2 can dissolve significantly into the IL phase, but no ionic liquid dissolves in the scCO2. Thus, the phase behavior of IL–scCO2 systems, including the partitioning of organic

• decrease in the viscosity of the IL solution, improving the mass transfer. Finally, the work under continuous flow conditions avoided the deactivation of this sensitive catalyst, as observed during its recycling in the batch mode. The increased long-term stability of the catalyst was associated with the

PEG-embedded KBr₃: A recyclable catalyst for multicomponent coupling reaction for the efficient synthesis of functionalized piperidines

• Sanny Verma,
• Suman L. Jain and
• Bir Sain

Beilstein J. Org. Chem. 2011, 7, 1334–1341, doi:10.3762/bjoc.7.157

• generated. The relative stereochemistry at the C2 and C6 position was found to be anti, as confirmed by X-ray crystallographic analysis of 7a (Figure 1). Regeneration and recycling of the reagent 3 was checked through the reaction of aniline, benzaldehyde and ethyl acetoacetate as a model reaction. After

• was used for the subsequent run. The regeneration and recycling of the catalyst was checked for five runs. The catalytic activity remained almost unchanged for up to four runs (>78% yield), whereas it was found to decrease in further successive runs, and a very poor yield (about 45%) was obtained in

• , safer handling and efficient recycling of the catalyst make this more suitable and preferable than the existing organic ammonium tribromides [30][31]. The mechanism of this reaction is not clear at this stage, however, the reaction probably involves the in situ generation of HBr in the presence of

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

• crystallisations. In addition, the racemisation of the undesired enantiomer via methyl ester formation and treatment with sodium hydroxide was found to be feasible allowing efficient recycling of this material [47]. Imidazoles Imidazole is an important biological building block being present in the amino acid

Air-stable, recyclable, and time-efficient diphenylphosphinite cellulose-supported palladium nanoparticles as a catalyst for Suzuki–Miyaura reactions

• Qingwei Du and
• Yiqun Li

Beilstein J. Org. Chem. 2011, 7, 378–385, doi:10.3762/bjoc.7.48

• ][41][42][43][44]. This class of supported palladium catalysts would solve the basic problems of homogeneous catalysts, i.e., the separation and recycling of the catalysts. This palladium complex catalyst also has the advantage of avoiding contamination of the products by residue ligand and metal

• recovered catalyst after being reused six times (b) at the same magnification. Recycling of Cell–OPPh2–Pd0 for the Suzuki reaction. Reaction conditions: 4-iodoanisole (1.0 mmol), phenylboronic acid (1.2 mmol), K2CO3 (2.0 mmol), Cell–OPPh2–Pd0 (0.015 g, 0.005 mmol of Pd), and 5.0 cm3 95% ethanol heating

Studies on Pd/NiFe₂O₄ catalyzed ligand-free Suzuki reaction in aqueous phase: synthesis of biaryls, terphenyls and polyaryls

• Sanjay R. Borhade and
• Suresh B. Waghmode

Beilstein J. Org. Chem. 2011, 7, 310–319, doi:10.3762/bjoc.7.41

• led to multiple coupling products in good to excellent yields (Table 5, entries 1–16). The feasibility of recycling the Pd/NiFe2O4 was examined (Supporting Information File 1). The recycling experiment was performed on the model reaction (iodobenzene with phenylboronic acid). After completion of the

• reaction of di- and trihaloaryls with arylboronic acida. Supporting Information Scanning electron microscope image, X-ray photoemission spectrum, X-ray powder diffraction pattern, catalytic activity of different loading of palladium over NiFe2O4, catalyst recycling studies and 1H and 13C NMR for the

Achiral bis-imine in combination with CoCl₂: A remarkable effect on enantioselectivity of lipase-mediated acetylation of racemic secondary alcohol

• K. Arunkumar,
• M. Appi Reddy,
• T. Sravan Kumar,
• B. Vijaya Kumar,
• K. B. Chandrasekhar,
• P. Rajender Kumar and
• Manojit Pal

Beilstein J. Org. Chem. 2010, 6, 1174–1179, doi:10.3762/bjoc.6.134

• enantioselectivity was observed in lipase-mediated preparation of alcohols and amines [7][8][9]. These biocatalysts work under mild reaction conditions, and their immobilized forms, being stable in organic solvents, have allowed an easy separation of products and the potential recycling of the enzyme, thereby

Progress in metathesis chemistry

• Karol Grela

Beilstein J. Org. Chem. 2010, 6, 1089–1090, doi:10.3762/bjoc.6.124

• of reasons, such as the still not perfect stability and sometimes low activity of existing catalysts, problems with removing/recycling of catalysts after the reaction, unfavorable patent situation and licensing strategies etc. [4]. Fortunately, the international community of chemists, fully aware of

Kinetics and mechanism of vanadium catalysed asymmetric cyanohydrin synthesis in propylene carbonate

• Michael North and
• Marta Omedes-Pujol

Beilstein J. Org. Chem. 2010, 6, 1043–1055, doi:10.3762/bjoc.6.119

• asymmetric addition of TMSCN [26][27][28] and KCN [13] to aldehydes and are more enantioselective, but less reactive than the titanium based catalyst 1. Complexes 1 and 2 have been commercialized [10][29][30], immobilized to facilitate their recycling [31][32][33][34][35][36][37][38][39][40][41][42][43] and

Suzuki–Miyaura cross-coupling reaction of 1-aryltriazenes with arylboronic acids catalyzed by a recyclable polymer-supported N-heterocyclic carbene–palladium complex catalyst

• Guangming Nan,
• Fang Ren and
• Meiming Luo

Beilstein J. Org. Chem. 2010, 6, No. 70, doi:10.3762/bjoc.6.70

• arenediazonium salt surrogates in the Suzuki–Miyaura cross-coupling reaction [29]. Pd2(dba)3 and P(tBu)3 were used as catalyst in this reaction where, as in most of homogeneous catalytic systems, the difficulties of catalyst recovery and recycling constitute major problems. One possible solution to these

• reactiona. Effect of the catalyst loading on the cross-coupling reactiona. Effect of the molar ratio of substrates on the cross-coupling reactionsa. Recycling of the polymer-supported NHC–Pd catalyst 1a. Cross-coupling of 1-aryltriazenes and arylboronic acids catalyzed by the polystyrene-supported NHC–Pd

Pd-catalyzed decarboxylative Heck vinylation of 2-nitrobenzoates in the presence of CuF₂

• Lukas J. Gooßen,
• Bettina Zimmermann and
• Thomas Knauber

Beilstein J. Org. Chem. 2010, 6, No. 43, doi:10.3762/bjoc.6.43

• also opened up opportunities to reduce the problematic salt load of these transformations. In this context, De Vries developed decarbonylative Heck reactions of benzoic homoanhydrides – a salt-free process for Heck vinylations, which however, requires recycling of the arenecarboxylate leaving group [17

Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions

• Gajanan M. Pawar,
• Jochen Weckesser,
• Siegfried Blechert and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2010, 6, No. 28, doi:10.3762/bjoc.6.28

• their MS spectra as well as by their retention times using commercially available compounds as reference material. Recyclability studies with poly(M1-b-M2)-Rh: Hydroformylations were carried out as described above. For recycling, the product was extracted with diethyl ether (4 × 10 mL). Fresh 1-octene