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

• synthesizing isoquinoline derivatives using LSA-FAS-Cu as catalyst was investigated. As shown in Table 6, LS-FAS-Cu could promote 2-(phenylethynyl)benzaldehyde (11a) and urea (12a) to generate 3-phenylisoquinoline (13a) in excellent yield, while the referential catalysts showed inferior catalytic activity

• acetophenones and 1,3-diaminopropane to synthesis 2‑arylpyridine derivatives.a Acid density of catalyst. Substrate scope of the ketones catalyzed by LSA-FAS-Cu. LS-FAS-Cu catalyzed synthesis of aminonaphthalene derivatives.a Synthesis of the 3-phenylisoquinoline from 11a and urea (12a).a Supporting Information

Incorporation of a metal-mediated base pair into an ATP aptamer – using silver(I) ions to modulate aptamer function

• Marius H. Heddinga and
• Jens Müller

Beilstein J. Org. Chem. 2020, 16, 2870–2879, doi:10.3762/bjoc.16.236

• ) at 65 °C for 15 min. They were purified using denaturing polyacrylamide gel electrophoresis (gel solution: 7 M urea, 1 TBE buffer, 14 or 18% (depending on the length of the oligonucleotide) polyacrylamide/bisacrylamide (29:1); loading buffer: 11.8 M urea, 42 mM Tris·HCl (pH 7.5), 0.83 mM EDTA (pH 8.0

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

• source of nitrogen has also been varied from the classical use of ammonia. The most common nitrogen source reported in literature is ammonium acetate (3). Others include the use of oxahydrazines, primary amines, and urea. The oxidation of dihydropyridines to pyridines has been achieved using mild

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• bis(carbazolyl)urea-derived receptor allowed the sensitive detection of diphosphate in water by surface plasmon resonance (SPR) [29]. Silica nanoparticles containing a dye coordinated to a bis(zinc(II)–DPA) receptor released the dye upon diphosphate binding [30], and thus producing an optical signal

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• enantioselectivities (20 examples, up to >99:1 er), with a quantum yield of 0.013. While there has been significant progress using bifunctional catalysts, dual catalytic systems can offer other modes of reactivity. For instance, Jiang et al. developed a urea-catalysed formal arylation of benzofuranones 215, using

• "Brønsted acid catalysis", yet interestingly their conjugate bases can also be used as efficient hydrogen bonding catalysts. Knowles et al. showed that a tricatalytic system using chiral phosphate 235 can mediate the deracemisation of cyclic urea rac-236 (Scheme 36) [97]. The proposed mechanism involves a

Regiodivergent synthesis of functionalized pyrimidines and imidazoles through phenacyl azides in deep eutectic solvents

• Paola Vitale,
• Luciana Cicco,
• Ilaria Cellamare,
• Filippo M. Perna,
• Antonio Salomone and
• Vito Capriati

Beilstein J. Org. Chem. 2020, 16, 1915–1923, doi:10.3762/bjoc.16.158

• imidazole (32–98% yield) and pyrimidine derivatives (45–88% yield), with a broad substrate scope, when using deep eutectic solvents [choline chloride (ChCl)/glycerol (1:2 mol/mol) and ChCl/urea (1:2 mol/mol)] as environmentally benign and non-innocent reaction media, by modulating the temperature (25 or 80

• material only (conversion: 81%, Table 2, entry 1). The employment of ChCl/urea (1:2 mol/mol) as the eutectic mixture provided 7a in 57% yield and 3a/3a' in 43% yield, but with full conversion (Table 2, entry 2). By lowering the equivalents of Et3N up to 1, or alternatively using K2CO3 (3 equiv) as a base

• , in ChCl/urea, the yield of 7a dropped down up to 33% and that of 3a/3a' up to 25% (Table 2, entries 3–5). By changing the solvent to pure Gly, 7a and 3a/3a' now formed in 52 and 37% yield, respectively (Table 2, entry 6). When Et3N (3 equiv) was alternatively used as the sole solvent, the formation

Design, synthesis and application of carbazole macrocycles in anion sensors

• Alo Rüütel,
• Ville Yrjänä,
• Sandip A. Kadam,
• Indrek Saar,
• Mihkel Ilisson,
• Astrid Darnell,
• Kristjan Haav,
• Tõiv Haljasorg,
• Lauri Toom,
• Johan Bobacka and
• Ivo Leito

Beilstein J. Org. Chem. 2020, 16, 1901–1914, doi:10.3762/bjoc.16.157

• example, a carbazole-urea macrocycle was reported previously [10], however, the binding of anions occurred outside the receptor due to modest dimensions of the macrocyclic cavity. Using click-chemistry, a carbazole-triazole macrocycle, “tricarb”, was prepared that showed the ability to form non-covalent

• carboxylates were modelled computationally using COSMO-RS. Several observations were made from the computational structures. Intramolecular hydrogen bonds between the urea carbonyl and the carbazole NH protons were present in macrocycles MC001 and MC003, as indicated in Figure 4. The rings of these macrocycles

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• performed by using the model substrates benzaldehyde (2a, 1.0 mmol), ethyl acetoacetate (4, 1.0 mmol), and urea (5, 1.0 mmol) in H2O (3.0 mL) in the absence of a catalyst under ultrasound irradiation at 45–50 °C for 60 min. It was observed that the reaction proceeded with a very low yield (20%) of product

• . The obtained results are summarized in Table 6. Benzaldehyde (2a) underwent the reaction with ethyl acetoacetate (4) and urea (5) to obtain the corresponding dihydropyrimidinone 7a in 97% yield (Table 6, entry 1). Benzaldehyde derivatives bearing electron-donating groups, such as 4-Me (2b), 4-OMe (2e

• ), 3,4-dimethoxy (2f), 3-OH (2r), and 2-OH (2h), respectively, at different positions on the ring reacted well with ethyl acetoacetate (4) and urea (5) to produce the products, 7b–f in good isolated yields that ranged from 92–96% (Table 6, entries 2–6). A benzaldehyde derivative with an electron

Stereoselective Biginelli-like reaction catalyzed by a chiral phosphoric acid bearing two hydroxy groups

• Xiaoyun Hu,
• Jianxin Guo,
• Cui Wang,
• Rui Zhang and
• Victor Borovkov

Beilstein J. Org. Chem. 2020, 16, 1875–1880, doi:10.3762/bjoc.16.155

• DHPMs becomes an urgent and paramount task. In connection with this, multicomponent Biginelli and Biginelli-like reactions of aldehydes, urea/thiourea, and enolizable carbonyls revealed as very efficient tools to prepare DHPMs [3]. Although the Biginelli reaction was firstly discovered over a century

• ago [10], little attention was given to asymmetric pathways. Only in 2003, Juaristi and Muñoz-Muñiz have reported the reaction of benzaldehyde, urea, and methyl acetoacetate using a chiral amide with CeCl3 for the first time. However, only 40% enantiomeric excess (ee) was obtained [11]. Then, Zhu

One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

• Gui-Feng Kang and
• Gang Zhang

Beilstein J. Org. Chem. 2020, 16, 1447–1455, doi:10.3762/bjoc.16.120

• chemistry demands. Several methods were reported for the synthesis of triazinethione analogs. One of the most popular methods involved the reaction of a carboximidamide [16], or urea [17] with isothiocyanates. The C=S bond in the latter is highly polar, with the carbon atom always positive and therefore

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• of activated carbons is possible at the precursor stage or as a modification step after the production of activated carbons and results mostly in a basic character of the prepared materials. Typical nitrogen agents are ammonia, urea or amines. Different types of nitrogen-containing functional groups

• found by ammoxidation of demineralized coal in the last preparation step after carbonization and activation [10]. Hu and coworkers synthesized nitrogen-doped carbon materials from coconut shell by urea modification and K2CO3 activation. The carbonized precursor is mixed with urea (1:1 weight ratio

• ), heated and the unreacted urea is removed by a washing step with hot water. Subsequently, the urea-treated samples were activated. The treatment with urea enhanced significantly the nitrogen content in the samples, while the final amount of nitrogen was reduced by the activation step [63][113]. Activated

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• thermal decomposition of urea at 550 °C for 2 h afforded the CN polymer, which possesses abundant –NH2 functional groups. The heterogeneous photocatalyst carbon nitride-hemin (CNH) was prepared after an amidation reaction between a carboxyl group of Fe(III) protoporphyrin IX and an amino group of the CN

Copper catalysis with redox-active ligands

• Agnideep Das,
• Yufeng Ren,
• Cheriehan Hessin and
• Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

• iminosemiquinone redox-active ligand which was oxidized to iminobenzoquinone. The Canary group [30] reported a redox-reconfigurable copper catalyst that exhibits reversal of its helical chirality through redox stimuli (Scheme 8). Combining ʟ-methionine and catalytic urea groups with two different copper salts as

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

• ]. Generally, urea (72) was calcined and then, CuCl2 was immobilized using sonication (Scheme 13). The nanopolymeric catalyst was applied as a reusable nanocatalyst for promoting the 1,3-dipolar cycloaddition of nitroolefins/phenylacetylenes and sodium azide in water at ambient temperature. High yields of the

Small anion-assisted electrochemical potential splitting in a new series of bistriarylamine derivatives: organic mixed valency across a urea bridge and zwitterionization

• Keishiro Tahara,
• Tetsufumi Nakakita,
• Alyona A. Starikova,
• Takashi Ikeda,
• Masaaki Abe and
• Jun-ichi Kikuchi

Beilstein J. Org. Chem. 2019, 15, 2277–2286, doi:10.3762/bjoc.15.220

• Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, Japan Institute of Physical and Organic Chemistry, Southern Federal University, pr. Stachki 194/2, Rostov on Don, 344090, Russian Federation 10.3762/bjoc.15.220 Abstract We report the synthesis of a new bistriarylamine series having a urea

• substantially than did a bulky one. The effects contrary to those reported in conventional MV systems were explained by zwitterionization through hydrogen bonding between the urea bridge and the counteranions, increasing the electronic interactions between two triarylamino units. Furthermore, we clarified the

• intervalence charge transfer characteristics of the zwitterionic MV state. Keywords: anion binding; electrochemistry; hydrogen bonding; triarylamine; urea; zwitterionic mixed valency; Introduction Mixed-valence (MV) compounds have received increasing attention from the viewpoint of fundamental research on

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• selectivity of this receptor for chloride anion is due to the cavity size (see Figure 3) [37]. 2.2. Optical anion sensing by 1,2,3-triazolium macrocycles within porphyrin cages Various porphyrin-based host supramolecules containing hydrogen-bond donor groups such as integrated amide, urea, pyrrole, ammonium

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• 54% and 35% yields, respectively. Corona[3]arene[3]tetrazine bearing even a urea group (3f) was synthesized analogously from the reaction of 1f with 2 when DABCO was employed as a base instead of DIPEA (Scheme 1). It was worth addressing that a chemical yield of 52% implied roughly a 90% yield for

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

A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

• András György Németh,
• György Miklós Keserű and
• Péter Ábrányi-Balogh

Beilstein J. Org. Chem. 2019, 15, 1523–1533, doi:10.3762/bjoc.15.155

• afford isothiocyanate and harmless urea [63][64][65], but one should note that the instability of the nitrile oxides leads to many byproducts, turning this approach less attractive. The synthesis of isothiocyanates starting from isonitriles involves sulfur-containing reagents such as thallium

Bambusuril analogs based on alternating glycoluril and xylylene units

• Tomáš Lízal and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2019, 15, 1268–1274, doi:10.3762/bjoc.15.124

• ; supramolecular chemistry; Introduction Macrocycles consisting of urea building blocks play an important role in supramolecular chemistry [1]. Urea N–H motifs provide macrocycles with the ability to act as anion receptors due to the stabilizing effect of N–H···anion hydrogen bonding [2][3][4]. Furthermore, the

• urea groups can participate in intermolecular hydrogen bonding resulting in the formation of tubular [5][6][7] or gel-like [8] structures. Ureas lacking of N–H hydrogen atoms such as ethyleneureas, glycolurils, and biotin are also important building blocks of macrocyclic receptors such as cucurbiturils

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• reaction reported in 1893 comprises the acid–catalyzed condensation of ethyl acetoacetate, benzaldehyde and urea to generate 3,4-dihydropyrimidin-2(1H)-one [41]. From that time, the reaction was extended to Lewis-acid catalysis and the use of other solvents such as methanol or aprotic solvents such as THF

• , etc. The urea component has the main structural restrictions, since monosubstituted alkyl ureas work well but thioureas have provided much lower yields. Wang et al. produced a library of steroidal [17,16-d]pyrimidine derivatives such as 40 employing a particular extension of the Biginelli reaction

• based on the use of 17-ketosteroids and chlorotrimethylsilane (TMSCl) as catalyst, which enables the formation of the nucleophilic enolate that attacks either benzaldehyde or its urea imine derivative [39]. Varied ketosteroids were employed, including methylestrone 39, dehydroepiandrosterone acetate and

A three-component, Zn(OTf)₂-mediated entry into trisubstituted 2-aminoimidazoles

• Alexei Lukin,
• Anna Bakholdina,
• Anna Kryukova,
• Alexander Sapegin and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2019, 15, 1061–1064, doi:10.3762/bjoc.15.103

• . Herein, we present the preliminary results of these studies. Results and Discussion Urea 4a (prepared by reacting propargylamine with 4-(trifluoromethoxy)benzyl isocyanate) was reacted with an equivalent amount of benzylamine in refluxing toluene in the presence of various Lewis acids. To our delight

• preparation of ureas 4 could, in principle, enable a three-component entry to imidazoles 5 (an attractive option from the standpoint of library array synthesis), we compared the isolated yield of the above reaction (with the ready-made urea 4a) with the yield obtained in the three-component format. To our

Towards the preparation of synthetic outer membrane vesicle models with micromolar affinity to wheat germ agglutinin using a dialkyl thioglycoside

• Dimitri Fayolle,
• Nathalie Berthet,
• Bastien Doumeche,
• Olivier Renaudet,
• Peter Strazewski and
• Michele Fiore

Beilstein J. Org. Chem. 2019, 15, 937–946, doi:10.3762/bjoc.15.90

• color was developed using OPD (100 μL per well, 0.4 mg mL−1 in 0.05 M phosphate-citrate buffer) and urea hydrogen peroxide (0.4 mg mL−1). The reaction was stopped after 10 min by adding H2SO4 (30% v/v, 50 μL per well) and the absorbance was measured at 490 nm. The percentage of inhibition was determined

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

• Iveta Chena Tichá,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

• aldol reaction catalyzed by β-CD with L-proline attached through a urea moiety. Therefore, mainly proline-derived CDs have been previously tested as organocatalysts and mainly in aldol-type reactions. The limited number of functional groups attached to CD comprising mainly L-proline restricts the

Cyclopropene derivatives of aminosugars for metabolic glycoengineering

• Jessica Hassenrück and
• Valentin Wittmann

Beilstein J. Org. Chem. 2019, 15, 584–601, doi:10.3762/bjoc.15.54

• amide [18], carbamate [19], or most recently a urea linkage [20] have been reported. Terminal alkenes are small which is beneficial for being accepted by the enzymes involved in glycan biosynthesis. However, they react only slowly in the DAinv reaction [20]. In contrast, ring-strained alkenes, such as