Catalytic Wittig and aza-Wittig reactions

• Zhiqi Lao and
• Patrick H. Toy

Beilstein J. Org. Chem. 2016, 12, 2577–2587, doi:10.3762/bjoc.12.253

• no life cycle assessments have been performed, they do seem to be rather “green” since no redox cycling is necessary, and there appear to be few constraints to their potential application. Recyclable polymer-supported arsine for catalytic Wittig-type reactions. Various phosphine oxides used as pre

Selective and eco-friendly procedures for the synthesis of benzimidazole derivatives. The role of the Er(OTf)₃ catalyst in the reaction selectivity

• Natividad Herrera Cano,
• Jorge G. Uranga,
• Mónica Nardi,
• Antonio Procopio,
• Daniel A. Wunderlin and
• Ana N. Santiago

Beilstein J. Org. Chem. 2016, 12, 2410–2419, doi:10.3762/bjoc.12.235

• the use of Er(OTf)3 as catalyst provides many advantages over previous ones such as it makes use of an economical, eco-friendly and recyclable catalyst, excellent yields in short reaction times, a simple procedure, short reaction times, and an easy work-up. In addition to the above mentioned

• environmentally friendly one-pot method for the simple and selective synthesis of 1,2-disubstituted or 2-substituted benzimidazoles, starting from o-phenylenediamine in the presence of aromatic or aliphatic aldehydes. The use of Er(OTf)3 as commercially available and easily recyclable catalyst promoted the

β-Amino functionalization of cinnamic Weinreb amides in ionic liquid

• Yi-Ning Wang,
• Guo-Xiang Sun and
• Gang Qi

Beilstein J. Org. Chem. 2016, 12, 2372–2377, doi:10.3762/bjoc.12.231

• distinct advantages of the use of 2-NsNCl2 as an inexpensive and stable nitrogen/halogen source and the ionic liquid as a recyclable reaction media. Nine examples were examined, and modest to good isolated chemical yields (40–83%) were obtained. Keywords: aminochlorination; β-amino functionalization

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

• are improved and selectivity is enhanced or modified [13]. In this regard, heterogeneous catalysis in general and zeolites in particular are remarkably efficient since they permit the replacement of toxic mineral acids and oxidants by easily recyclable catalysts [14]. One approach to improve yields

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

• in which a heterogeneous catalyst triggers the selective esterification of levulinic acid with a stoichiometric amount of alcohol. In the last years, many methods have been developed for the transformation of homogeneous catalysts into recyclable heterogeneous ones. To prevent leaching, a common

• be easily prepared from commercial reagents and proved very robust. It is very active and selective, water-tolerant and recyclable. It represents therefore an interesting and complementary alternative to existing esterification catalysts. Together with the absence of solvents and of any molar excess

One-pot synthesis of 4′-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling

• Roman Yu. Peshkov,
• Elena V. Panteleeva,
• Wang Chunyan,
• Evgeny V. Tretyakov and
• Vitalij D. Shteingarts

Beilstein J. Org. Chem. 2016, 12, 1577–1584, doi:10.3762/bjoc.12.153

• alkyl moiety. The main advantages of this method are experimental simplicity, utilization of commercially accessible reagents (terephthalonitrile, metallic sodium, substituted aromatic monocarbonitriles, alkyl bromides), together with a recyclable solvent – liquid ammonia – which is now considered as a

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• substituted isatins 30 with aniline (32) and dimethyl- or diethyl phosphite under solvent-free conditions in the presence of magnetic Fe3O4 nanoparticle-supported phosphotungstic acid as a recyclable catalyst at 80 °C furnished α-aminophosphonates 33 in yields from 80% to 98% depending on the reaction time

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• excess when the cis-aminoindanol-based prolinamide 56, acting as bifunctional recyclable catalyst, was used (Scheme 18). Later, based on this previous work, the same research group extended the methodology to different ketones 55, rendering the syn-products 57 with excellent yield and high selectivity

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• on this area from Truong et al. [75] showed that the heterogeneous and recyclable Cu2(BDC)2(BPY) catalyst (BDC = benzene- 1,4-dicarboxylate; BPY = 4,4′-bipyridine) could catalyze this kind of amidation reaction with excellent selectivity to provide ynamides. Another point was that the C–H bond could

Chiroptical properties of 1,3-diphenylallene-anchored tetrathiafulvalene and its polymer synthesis

• Masashi Hasegawa,
• Junta Endo,
• Seiya Iwata,
• Toshiaki Shimasaki and
• Yasuhiro Mazaki

Beilstein J. Org. Chem. 2015, 11, 972–979, doi:10.3762/bjoc.11.109

• 1,3-bis(4-iodophenyl)-1,3-diisopropylallene (9) and organozinc species derived from 4,5-bis(methylthio)TTF. Optical resolution of the enantiomer 3 and its precursor 9 was achieved by a recyclable HPLC on a chiral stationary phase. The ECD spectra were measured, and the obtained spectra allowed for the

• recorded on JASCO FT/IR-610 spectrometer. Melting points were determined with Yanaco melting point apparatus. Elemental analyses were performed on Perkin Elmer PE 2400-II CHNA/O analyzer. Optical resolution was carried out with recyclable preparative HPLC (JAI Model LC-9204) equipped with Daicel CHIRALPAK

• of 3. Synthesis of chiral (R)-PTDPA and (S)-PTDPA. Redox potentials of 3 and PTDPA.a Absorption maxima of 3, 10 and PTDPA.a Supporting Information Supporting Information File 216: Experimental procedures, characterization data, copies of 1H and 13C NMR charts, recyclable chiral HPLC chart and DFT

Organophosphorus chemistry

• Paul R. Hanson

Beilstein J. Org. Chem. 2014, 10, 2087–2088, doi:10.3762/bjoc.10.217

• their use as recyclable heterogeneous reagents, the Atherton–Todd reaction, cyclic phosphonium ionic liquids with distinct properties, photo-removable phosphate protecting groups, new methods of C–H functionalization using phosphoryl-related directing groups, the exciting chemistry of substituted

Supercritical carbon dioxide: a solvent like no other

• Jocelyn Peach and
• Julian Eastoe

Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196

• being readily available, cheap, non-flammable, recyclable and unrestricted by the US Environmental Protection Agency (EPA) [3][5][6][7][8][9][10][11][12][13][14][15], supercritical CO2 (scCO2) is non-toxic so could potentially be used for the production of consumable products, such as pharmaceutical and

Rasta resin–triphenylphosphine oxides and their use as recyclable heterogeneous reagent precursors in halogenation reactions

• Xuanshu Xia and
• Patrick H. Toy

Beilstein J. Org. Chem. 2014, 10, 1397–1405, doi:10.3762/bjoc.10.143

• to be an efficient and highly recyclable catalyst for aldehyde and ketone cyanosilylation reactions from which the products could also be obtained pure after only filtration and solvent removal [30]. It should be noted that the grafts of the rasta resins reported are random co-polymers, and the

• repeatedly recovered and reused without an observable decrease in its reactivity. However, whereas 16 could be reused directly after recover, reusing 18 required washing it with an aqueous solution of Na2CO3 after each reaction. Conclusion In summary, we have designed and synthesized recyclable heterogeneous

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• years the development of new and effective nanostructured catalytic systems dominated the gold-catalyzed approach to A3-coupling. For example, ultrasmall gold(0) nanoparticles embedded in a mesoporous carbon nitride stabilizer [27] proved to be a highly active, selective and recyclable heterogeneous

• for Au NP, and these heterogeneous systems were tested as recyclable catalysts in an A3-coupling. The former was effective in three simple model reactions as a bifunctional catalyst (Au/acid) in aqueous medium at 70 °C. The latter works well in chloroform at 60 °C and tolerates a number of substituted

• them on a mesoporous support, i.e., MCM-41. The authors tested them in A3-couplings and found that, although under homogeneous conditions the conversion to the respective propargylamine was higher than under heterogeneous ones, the heterogenized complexes were stable, recyclable for at least six cycles

One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger–aza-Wittig reaction

• Diego Carnaroglio,
• Katia Martina,
• Giovanni Palmisano,
• Andrea Penoni,
• Claudia Domini and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2013, 9, 2378–2386, doi:10.3762/bjoc.9.274

• preparation of triphenylphosphine-loaded cross-liked cyclodextrin complexes as recyclable green catalyst [39]. The reactivity of polystyrene-supported reagents strongly depends on the choice of solvent that can influence polymer swelling [40]. Solvent choice is therefore an important issue as it must allow

Silica sulfuric acid: a reusable solid catalyst for one pot synthesis of densely substituted pyrrole-fused isocoumarins under solvent-free conditions

• Sudipta Pathak,
• Kamalesh Debnath and
• Animesh Pramanik

Beilstein J. Org. Chem. 2013, 9, 2344–2353, doi:10.3762/bjoc.9.269

• isocoumarins were formed in good yields. This synthetic method has several advantages such as the employment of solvent-free reaction conditions without the use of any toxic reagents and metal catalysts, the ease of product isolation, the use of a recyclable catalyst, the low cost, the easy availability of the

Practical synthesis of indoles and benzofurans in water using a heterogeneous bimetallic catalyst

• Cybille Rossy,
• Eric Fouquet and
• François-Xavier Felpin

Beilstein J. Org. Chem. 2013, 9, 1426–1431, doi:10.3762/bjoc.9.160

• base. Current studies focusing on the preparation of more robust and recyclable heterogeneous bimetallic catalysts for batch and flow processes are underway in our laboratory. Experimental Catalyst preparation: The Pd–Cu/C was prepared by the following procedure. Pd(OAc)2 (119 mg, 0.5 mmol), Cu(OAc)2

Reactions of salicylaldehyde and enolates or their equivalents: versatile synthetic routes to chromane derivatives

• Ishmael B. Masesane and
• Zelalem Yibralign Desta

Beilstein J. Org. Chem. 2012, 8, 2166–2175, doi:10.3762/bjoc.8.244

• sieves have the advantage that they are recyclable. Chromane derivatives from the reaction of salicylaldehyde and enolates derived from α,β-unsaturated compounds The tandem reaction of salicylaldehyde and α,β-unsaturated compounds has proved to be a reliable route to chromane derivatives. In general

Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach

• Pankaj Chauhan and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240

• energy [1][2][3][4]. These requirements are fulfilled by preventing or minimizing the use of volatile and toxic solvents and reagents, minimizing chemical wastage, development of atom-economical processes and recyclable supported catalyst that are less toxic, biodegradable and can be used at low loading

Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

• Chittaranjan Bhanja,
• Satyaban Jena,
• Sabita Nayak and
• Seetaram Mohapatra

Beilstein J. Org. Chem. 2012, 8, 1668–1694, doi:10.3762/bjoc.8.191

• tertiary amine-modified diarylpyrrolinol-TMS ether III as a water-soluble and recyclable organocatalyst with 4-chlorobenzoic acid as cocatalyst (Scheme 5) for the synthesis of 2H-chromene derivatives 3. The electronic effect of the tertiary amine group in the modified catalyst was believed to enhance the

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

• the reaction mixture by simple fluorous solid-phase extraction (F-SPE) and used for the next round of reaction without further purification. Keywords: asymmetric fluorination; β-ketoester; fluorous cinchona ester; organocatalysis; recyclable chiral promoter; Introduction Fluorinated organic

• supported cinchona alkaloids have been developed as recyclable chiral promoters or organocatalysts. Among them, the Cahard group developed soluble polymer- and ionic-liquid-supported cinchona alkaloids for electrophilic fluorination [21][22]. The Fache and Soόs groups developed fluorous tag-attached

• cinchona alkaloids for catalytic Diels–Alder reactions [23][24]. Introduced in this paper is a new fluorous cinchona alkaloid ester for flourination of β-ketoesters. It is part of our recent effort on the development of recyclable fluorous reagents and organocatalysts for asymmetric synthesis [25][26][27

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

• -adamantylphenol derivatives through adamantylation of substituted phenols with adamantanols catalyzed by commercially available and recyclable ion-exchange sulfonic acid resin in acetic acid. The sole byproduct of the adamantylation reaction, namely water, could be converted into the solvent acetic acid by

• acid [19], could circumvent the drawbacks associated with using concentrated H2SO4. However, these strong organic protic acids are expensive and volatile, and thus their recovery poses many difficulties. Strongly acidic ion-exchange sulfonic acid resins have been extensively exploited as recyclable

• acid catalysts for organic syntheses in both laboratory and industry since they became commercially available [23][24][25][26]. The success of recyclable ion-exchange resins as substitutes for mineral acids in organic syntheses prompted us to study the possibility of using acidic sulfonic acid resin as

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

• Sanny Verma Suman L. Jain Bir Sain Chemical Sciences Division, Indian Institute of Petroleum (Council of Scientific and Industrial Research), Dehradun-248005, India 10.3762/bjoc.7.157 Abstract PEG-embedded potassium tribromide ([K+PEG]Br3−) was found to be an efficient and recyclable catalyst for

• . Keywords: heterocycles; metal free synthesis; multicomponent coupling; piperidine; recyclable catalyst; Introduction Multicomponent reactions [1][2][3][4][5], involving the one-pot reaction of three or more components to produce valuable compounds, have been recognized as one of the important tools to

• catalyst make these methods of limited utility. Thus, the development of a simple, cost-effective and recyclable catalyst for the efficient preparation of functionalized piperidines is particularly desired. Results and Discussion In the present paper, we report a simple, highly efficient and easily

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• solvents, an attractive alternative is the use of ionic liquids as the reaction solvent, which often affords inexpensive, recyclable (and therefore environmentally benign), and sustainable catalyst systems. For example, Aksin et al. demonstrated that ionic liquids were highly suitable reaction media for

Nano copper oxide catalyzed synthesis of symmetrical diaryl sulfides under ligand free conditions

• K. Harsha Vardhan Reddy,
• V. Prakash Reddy,
• A. Ashwan Kumar,
• G. Kranthi and
• Y.V.D. Nageswar

Beilstein J. Org. Chem. 2011, 7, 886–891, doi:10.3762/bjoc.7.101

• reactions mediated by recyclable copper oxide nanoparticles under ligand free conditions. This protocol avoids foul smelling thiols, for the synthesis of a variety of symmetrical diaryl sulfides, via the cross-coupling of different aryl halides with potassium thiocyanate, affording corresponding products in

• moderate to excellent yields. Keywords: aryl halides; aryl sulfides; copper oxide; cross-coupling; ligand free; potassium thiocyanate; recyclable; Introduction After the discovery of copper-promoted Ullmann reaction [1][2][3] for the construction of carbon-hetero atom bonds, several protocols have been

• and ligands [43], long reaction times [43][44], metal contamination of the final product, and non recyclability of the catalyst. This leads to increased costs as well as limiting the scope of the reaction. From the synthetic point of view, it is desirable to find novel recyclable catalytic systems