Nitroalkene reduction in deep eutectic solvents promoted by BH₃NH₃

• Chiara Faverio,
• Monica Fiorenza Boselli,
• Patricia Camarero Gonzalez,
• Alessandra Puglisi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2021, 17, 1041–1047, doi:10.3762/bjoc.17.83

• reproducible protocol to isolate the product without the use of any organic solvent was established, and the recyclability of the DES mixture was successfully investigated. Keywords: alternative solvents; atom economy; DES; nitro derivatives; reduction; Introduction The search for alternative solvents, not

• report the results of our explorative studies, aimed to develop a chemoselective nitroalkene reduction in DESs, with the goals to establish a reliable and reproducible protocol to isolate the product without the use of any organic solvent and to assess the recovery and the recyclability of the DES

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding

• Subrata Nath,
• Alexander Kappelt,
• Matthias Spengler,
• Bibhisan Roy,
• Jens Voskuhl and
• Michael Giese

Beilstein J. Org. Chem. 2021, 17, 124–131, doi:10.3762/bjoc.17.13

• interactions, which allow for dynamic responses to external stimuli [1]. In addition, the self-assembly of the complementary molecular entities provides an easy access to functional systems and enables recyclability and self-healing properties of the materials [2]. With respect to the formation of

A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles

• Bingbing Lai,
• Meng Ye,
• Ping Liu,
• Minghao Li,
• Rongxian Bai and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238

• to the fast deactivation of catalysts, which consequently impair the recyclability of the catalysts [8][9][10][11]. Therefore, special efforts should be paid to enhancing the robustness of heterogeneous metal catalysts. Sodium lignosulphonate (LS) is a waste from the paper-making industry, containing

• recyclability. However, the stability and durability of LS was very limited especially in polar solvents such as H2O, EtOH and at harsh conditions. In a further study of our previous work [15], a LS/dicationic ionic liquid composite was prepared via an ion exchange process, and then used as catalyst support for

• , which may be ascribed to the low loading capacity of Cu species (Table 6, entry 1 vs entries 2 and 3). In addition, by increasing the amount of catalyst, the yields could reach the ideal level (Table 6, entries 4 and 5). The recyclability of LS-FAS-Cu was investigated based on the three-component

One-pot multicomponent green Hantzsch synthesis of 1,2-dihydropyridine derivatives with antiproliferative activity

• Giovanna Bosica,
• Kaylie Demanuele,
• José M. Padrón and
• Adrián Puerta

Beilstein J. Org. Chem. 2020, 16, 2862–2869, doi:10.3762/bjoc.16.235

• reported by Cao and collaborators [19]. Catalyst characterization and recyclability The catalyst was analyzed by X-ray fluorescence (XRF) spectroscopy in order to ascertain the PW/Al2O3-support ratio. The mass percentage ratio of tungsten, which is the main component of the catalyst, and aluminium, the

Synergy between supported ionic liquid-like phases and immobilized palladium N-heterocyclic carbene–phosphine complexes for the Negishi reaction under flow conditions

• Edgar Peris,
• Raúl Porcar,
• María Macia,
• Jesús Alcázar,
• Eduardo García-Verdugo and
• Santiago V. Luis

Beilstein J. Org. Chem. 2020, 16, 1924–1935, doi:10.3762/bjoc.16.159

• -like phases (SILLPs) [33][34][35][36][37][38]. In these systems, the microenvironment provided by the ionic liquid-like units can have a remarkable influence on the overall process, particularly on the catalytic activity and recyclability of the supported species. Indeed, the appropriate design of the

• (Figure 6b). Under these conditions, the catalytic system was less active, but the leaching was reduced even further reaching a value of 0.04 ppm. The recyclability of the systems was also tested. In general, the catalysts assayed maintained the catalytic activity as far as an additional amount of RuPhos

• used for their preparation and this significantly affects its activity but also their recyclability [35][39]. The capacity to generate active catalytic species from the MNPs is essential in the first run, but the capacity of the system, including imidazolium fragments and remaining MNPs, to efficiently

One-pot synthesis of isosorbide from cellulose or lignocellulosic biomass: a challenge?

• Isaline Bonnin,
• Raphaël Mereau,
• Thierry Tassaing and
• Karine De Oliveira Vigier

Beilstein J. Org. Chem. 2020, 16, 1713–1721, doi:10.3762/bjoc.16.143

•  3). Optimal reaction conditions for the first step are middle temperatures to enhance the recyclability of Ru/C catalyst. 59% of sorbitol was obtained at 170 °C with 0.5 M of H2SO4, 20 bar of H2 for 2 h and in the presence of 0.02 mmol of Ru. The second step was performed starting from the first

• activity and recyclability of the catalyst was improved. A modification of the Ru/C hydrogenation catalyst’s surface by sulfonation and oxidative treatment was performed and had a significant effect on the catalyst properties in the isosorbide synthesis. Hence, strong acid sites are generated on the

• strong and medium acid site of NbOPO4-pH2 after its impregnation. The recyclability of NbOPO4-pH2 was performed for the two-step conversion of cellulose to isosorbide as the Ru/NbOPO4-pH2 recyclability was proved in a previous study in the conversion of cellulose to isosorbide [29]. A decrease of

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• chemistry as previously discussed. This combines the ease of separation and recyclability of a heterogeneous catalyst, with the detailed characterisation, accessibility and synthetic versatility of a homogeneous photocatalyst. Some desirable properties of a solid support are hence; (i) a strong

Reaction of indoles with aromatic fluoromethyl ketones: an efficient synthesis of trifluoromethyl(indolyl)phenylmethanols using K₂CO₃/n-Bu₄PBr in water

• Thanigaimalai Pillaiyar,
• Masoud Sedaghati and
• Gregor Schnakenburg

Beilstein J. Org. Chem. 2020, 16, 778–790, doi:10.3762/bjoc.16.71

• advantages of this protocol. Keywords: C–C-bond formation; C3-funtionalization of indole; diindolylmethane; Friedel–Crafts reaction; indole; indole-3-carbinol; large-scale synthesis; recyclability; Introduction (1H-Indol-3-yl)methanols have emerged as versatile pre-electrophiles for C–C functionalization

• this reaction. The base-catalyzed reaction has a benefit because it may avoid the formation of diindolylmethane and biindoles as byproducts [28]. Although these methods were useful, they have limitations and drawbacks, which are the use of organic solvents [24], difficulties in recyclability of the

• indole (1b, 8.5 mmol) with 2a (9.4 mmol, Scheme 1). In both reactions, the desired products are achieved in excellent yields (3a: 2.14 g, 98%; 3b: 2.39 g, 96%). The recyclability of the catalytic system n-Bu4PBr/K2CO3 of this protocol was investigated in the preparation of 3a using 1a (3.40 mmol), 2a

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• , the desired triazole products were generated through the [3 + 2] cycloaddition of the azide and alkyne. The recyclability analysis of these IPSi-supported Cu(I) and Cu(II) catalysts indicated seven consecutive runs with almost equivalent performances. In 2018, silica modified with a benzimidazole

• proceeded well using a catalytic amount of the synthesized catalyst 58 in water at 70 °C to create 1,4-disubstituted 1,2,3-triazole products in good to high yields (Scheme 9). In terms of recyclability, there was a continuous decrease in the catalytic activity of 58 from the first to the second to the third

• 24 h to produce a precipitate that was gathered and washed with water and ethanol (Scheme 18). It should be noted that 5.0 mol % of the 3D graphene/Cu nanocomposite 87 were sufficient to generate a high yield of the desired products in EtOH/H2O (1:1) at 70 °C. To screen the recyclability of 87, the

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• about the future availability of these metals at a reasonable cost. With regards to organic dyes, impressive developments have been achieved, but these catalysts might suffer from a low photochemical stability, and thus hampering their use and recyclability [7]. Therefore, alternative solutions have to

Oligomeric ricinoleic acid preparation promoted by an efficient and recoverable Brønsted acidic ionic liquid

• Fei You,
• Xing He,
• Song Gao,
• Hong-Ru Li and
• Liang-Nian He

Beilstein J. Org. Chem. 2020, 16, 351–361, doi:10.3762/bjoc.16.34

• recyclability and product separation. After decanting the upper product and washing the remaining IL with a small amount of dichloromethane, the weight of [HSO3-BDBU]H2PO4 was examined and then the fresh ricinoleic acid was added for the next cycle synthesis of oligomeric ricinoleic acid. The IL catalyst was

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• different functional groups (Table 2). It was found that the reactions tolerated carboxylic acid, ketone, halogen (Cl, Br, I, and F), aldehyde, amide, primary amine, secondary amine, and phenolic functional groups to a reasonably acceptable extent. Recovery and recyclability of the Ru nanocatalyst The

• reusability and recyclability of the solid RuNC was then tested in the reaction of 1a with 2a. The catalyst was recovered from the C–H alkenylation reaction and reused in subsequent reactions, with up to eight cycles (Figure S11, Supporting Information File 1). To recover the catalyst, the reaction mixture

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• this composite as a coin and applied directly as cathode for enantioselective hydrogenation of aromatic ketones. In this case they observed the remarkable stability as well as recyclability of the alkaloid@Cu composite making them reliable for further practical applications [40]. Further, alkaloid

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• heterogeneously catalyzed synthesis of imidazo[1,2-a]pyridines from 3 and ketones 20 has been reported (Scheme 7) [101]. Titania-supported CuCl2 (CuCl2/nano TiO2) played the role of catalyst in this transformation under aerobic conditions. Titania support helped in recyclability of the copper salt to four

• and lesser reaction time. Leaching of the metal ion was absent as tested by AAS, which ensured the recyclability of the catalyst to 5 synthetic cycles. Mechanistically the reaction proceeded by a nucleophilic attack of the alkyne on imine 133, resulting in the formation of propargylamine 134. The

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• . Recyclability of the BATA-MC catalyst The BATA-MC catalyst was recovered by column chromatography and its recyclability was investigated in the synthesis of 4a to demonstrate the eco-friendly nature of the catalyst. The catalytic activity remained nearly unchanged up to five cycles as shown in Figure 7

Ugi reaction-derived prolyl peptide catalysts grafted on the renewable polymer polyfurfuryl alcohol for applications in heterogeneous enamine catalysis

• Alexander F. de la Torre,
• Gabriel S. Scatena,
• Oscar Valdés,
• Daniel G. Rivera and
• Márcio W. Paixão

Beilstein J. Org. Chem. 2019, 15, 1210–1216, doi:10.3762/bjoc.15.118

• -supported chiral organocatalysts usually provides a much greener prospect for the synthesis of enantiomerically enriched building blocks [4][5][6]. Importantly, immobilized catalysts allow for both recyclability of the catalyst and the implementation of continuous-flow procedures, which usually encompass

Asymmetric synthesis of a high added value chiral amine using immobilized ω-transaminases

• Antonella Petri,
• Valeria Colonna and
• Oreste Piccolo

Beilstein J. Org. Chem. 2019, 15, 60–66, doi:10.3762/bjoc.15.6

• , enzyme recyclability, easy work-up and purification of the product [2][3][4][7][8][9][10][11][12][13]. Recently, we have reported a successful use of several immobilized TAs with IPA as amine donor [14]. Optically active 3-aminopiperidines and their N and/or N'-protected analogues, are important

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• handling, and even reusability [34]. Ionic liquids (ILs) have been extensively reported as green solvents in organic transformations, owing to their considerable properties such as the ability to dissolve a wide range of substances, very low vapor pressure, high thermal stability, recyclability, non

• products 8 with only 5 mol % loading. However, 10 mol % of the less acidic [Msim][ZnCl3] (4) and [Msim][CuCl2] (5) catalysts were applied to obtain the desired products 8 with excellent yields (Scheme 1). A recyclability study indicated three consecutive runs with a similar efficiency [38]. Other

• ) ILs in absence of any solvent. The [Dsim][CCl3COO] (18) and [Dsim][CF3COO] (19) ILs showed good recyclability and the catalysts were reused for three consecutive runs. In this case, the desired products were extracted by dry dichloromethane from the ionic liquid medium 18 or 19 and then the ionic

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• . The reaction works quite well with both electron-donating and electron-withdrawing substituents on the Baylis–Hillman alcohols. The protocol is also compatible with both diaryl and dialkyl sufides. What is even more interesting about this methodology is the recyclability and reusability of the ionic

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• more achievable. Nanocompartments such as polymersomes [40], micelles [41], dendrimers [42], and nanogels [43][44] represent smart and compact devices to carry out reactions in aqueous media. Besides, their facile recyclability make them very suitable as nanoreactors for a multitude of applications in

• process, as 200 ppm of Pd(OAc)2 worked like a co-catalyst being beneficial either for the reaction rate and the yields, and no product was observed without the Pd source. Furthermore, the recyclability of the catalyst was improved and the experiments could be repeated up to 5 runs with yields >90

• industry. A number of reasons can account for this. First of all, the construction of the nanoreactors is not always a cost-efficient process. Scalability and reproducibility in nanoreactor production also are key factors that have to be addressed. The recyclability and cost price should be improved to

Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry

• Katharina Hiebler,
• Georg J. Lichtenegger,
• Manuel C. Maier,
• Eun Sung Park,
• Renie Gonzales-Groom,
• Bernard P. Binks and
• Heidrun Gruber-Woelfler

Beilstein J. Org. Chem. 2018, 14, 648–658, doi:10.3762/bjoc.14.52

• obtained results are very promising although the relevant transformation needed higher catalyst amounts. Recyclability and metal leaching In the context of heterogeneous catalysis it is essential to investigate the actual nature of the catalysts during the reaction as well as the reusability and stability

• separated from the solution via filtration, washed, dried and reused for a new reaction with new substrates. Although during the filtration and drying steps catalyst loss could not be prevented, a high degree of recyclability was established and only a minor decrease of mass specific catalyst activity was

• trace amounts of catalytically active Pd into solution. Considering the application of the palladium catalysts in a continuous flow setup, recyclability as well as stability of the catalysts was substantiated and levels of leached Pd in the reaction mixture were determined to be below the critical limit

An efficient Pd–NHC catalyst system in situ generated from Na₂PdCl₄ and PEG-functionalized imidazolium salts for Mizoroki–Heck reactions in water

• Nan Sun,
• Meng Chen,
• Liqun Jin,
• Wei Zhao,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2017, 13, 1735–1744, doi:10.3762/bjoc.13.168

• extraction with a water immiscible solvent, while retaining the catalyst in the aqueous phase for recovery and potential reuse. Therefore, the recyclability of the Na2PdCl4/L1 catalytic system for Mizoroki–Heck reactions in water was examined by using the coupling of 4-bromoacetophenone (1a) and styrene (2a

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

• centrifugation of the reaction crude followed by drying under vacuum (90% of recovered enzyme; we will call it rCALB). This recovered material was reused to evaluate the enzyme recyclability after the mechanochemical protocol. When the reaction was carried out using the recovered enzyme the yield was not as good

Sustainable synthesis of 3-substituted phthalides via a catalytic one-pot cascade strategy from 2-formylbenzoic acid with β-keto acids in glycerol

• Lina Jia and
• Fuzhong Han

Beilstein J. Org. Chem. 2017, 13, 1425–1429, doi:10.3762/bjoc.13.139

• 3l was obtained with 67% yield. After investigating the scope of the synthesis of 3-substituted phthalides, the recyclability of glycerol was investigated for the reaction shown in Table 2. After completion of the condensation, the mixture was extracted with ethyl acetate. The glycerol phase was