A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

• Pieterjan Winant and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 2315–2320, doi:10.3762/bjoc.17.149

• multistep procedures requiring large amounts of toxic metal complexes [12][33][34]. Later improvements still demand prefunctionalization of the quinone substrate [35][36][37]. While effectively eliminating this requirement, CH bis-arylation using palladium complexes still suffers from regioselectivity

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• ]. PENAO triggers cell apoptosis by targeting the ANT protein, which is located in the mitochondria. More specifically, PENAO binds to the thiols located on the ANT peptide loops Cys57 and Cys257, which results in the formation of stable cyclic dithioarsinite complexes [5]. Arsenic drugs do not only bind

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• cavities. In this context, halides offer an advantage over various other anionic species because their spherical topology reduces the number of possible isomers or complexes upon interaction with the receptor. As a consequence, predictable cavity sizes based on the employed halide allows for easier

• display the role of the halide anions and how the predictability of binding properties towards these anions led to the development of a multitude of catalytic concepts and (supramolecular) catalyst systems. Hence, the possibility of employing the catalyst-bound halide anions in the key ion pair complexes

(Phenylamino)pyrimidine-1,2,3-triazole derivatives as analogs of imatinib: searching for novel compounds against chronic myeloid leukemia

• Luiz Claudio Ferreira Pimentel,
• Lucas Villas Boas Hoelz,
• Henayle Fernandes Canzian,
• Frederico Silva Castelo Branco,
• Andressa Paula de Oliveira,
• Vinicius Rangel Campos,
• Floriano Paes Silva Júnior,
• Rafael Ferreira Dantas,
• Jackson Antônio Lamounier Camargos Resende,
• Anna Claudia Cunha,
• Nubia Boechat and
• Mônica Macedo Bastos

Beilstein J. Org. Chem. 2021, 17, 2260–2269, doi:10.3762/bjoc.17.144

• with the interactions found for IMT in the 3PYY crystal. The analysis of the inhibitor complexes 2c and 2g and BCR-Abl-1 showed interactions similar to those described for IMT (Figure 4a). Thus, compound 2c presented hydrogen-bonding interactions with Asp400 and Leu383 (hydrogen bonding energy of −1.31

• Virtual Docker v6.0 (MVD) program was used to predict the complexes and energies of interaction between the enzyme BCR-Abl 1 and inhibitors 2c, 2d, and 2g. The crystallographic structures of the enzyme BCR-Abl-1, complexed with IMT, were extracted from the Protein Data Bank (PDB code: 3PYY) [37]. The

• ; maximum iteration = 2000; scaling factor = 0.50; offspring scheme = Scheme 1; termination scheme = variance-based; crossover rate = 0.90. Due to the stochastic nature of the algorithm search, ten independent simulations per ligand were performed to predict the binding mode. Consequently, the complexes

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• opportunities for late-stage diversification of complex molecules. Despite the significant advances, the photoredox-mediated nickel-catalyzed C‒H functionalization is still in its infancy. Thus far, expensive iridium-based complexes are the most common photocatalysts and are essential to achieve satisfactory

Facile and innovative catalytic protocol for intramolecular Friedel–Crafts cyclization of Morita–Baylis–Hillman adducts: Synergistic combination of chiral (salen)chromium(III)/BF₃·OEt₂ catalysis

• Karthikeyan Soundararajan,
• Helen Ratna Monica Jeyarajan,
• Raju Subimol Kamarajapurathu and
• Karthik Krishna Kumar Ayyanoth

Beilstein J. Org. Chem. 2021, 17, 2186–2193, doi:10.3762/bjoc.17.140

• M(salen) complexes. Intramolecular Friedel–Crafts cyclizations in Morita–Baylis–Hillman adducts are known to undergo annulations generating cyclic frameworks of indene. To the best of our knowledge, five reports are cited for the intramolecular FC reaction in MBH adducts. The first report was by

• possibly be utilized for the current investigation with expectations to minimize the formation of regioisomers, dimerized side products and overcome the usage of allylic-OH protected MBH adducts. Metallosalen complexes can be easily prepared and safely handled. The stability of metallosalen complexes

• convinced us to explore them as suitable chiral Lewis acid catalysts for the Friedel–Crafts cyclization of MBH adducts. Mononuclear(salen) complexes of aluminium, chromium, manganese and cobalt were chosen and screened for the current investigation. Results and Discussion To evaluate the scope of the

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• polymerization of azulene (1) by iodine or bromine to obtain polyazulene–iodine/bromine complexes (PAz-I2/PAz-Br2) (Scheme 1). The PAZ-I2 complex was found to be insoluble whereas PAZ-Br2 was sparingly soluble in most of the organic solvents. Although no structure was proposed for these polymer complexes, based

• aqueous acid solution. Further, the coordination of polymers 37 and 39 to a multinuclear Ru cluster was investigated by the same group [32]. The organometallic complexes 40–43 were synthesized by treating polymers 37 and 39 with Ru3(CO)12 in refluxing xylene (Scheme 9). The ruthenium content in these

• complexes can be varied by changing the ratio of reactants during the reaction. The 1H NMR chemical shift values of the azulene unit were used as a tool to determine the extent of ruthenium coordination to the azulene units in the polymer backbone as the coordinated azulene displays upfield-shifted

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• develop C–H activation methods, since it can be used as the metallic center of innovative and elaborated complexes [35][36]. Scandium-based catalysts have not been directly applied to the synthesis of known biologically active compounds via C–H activation reactions. Therefore, as challenging as it seems

• usually mediated by V(V) and V(IV)-oxo-peroxo complexes, which are produced in situ from vanadium-oxo and dioxo precatalysts in the presence of oxidants, such as H2O2, O2, and tert-butyl hydroperoxide (TBHP) [76][77][78][79][80][81][82]. Inorganic acids and chelating and non-chelating carboxylic acids

• providing evidence for the involvement of radical species and a few suggesting non-radical pathways in the presence of a Lewis acid or oligovanadate complexes in solution [77][82][83][84][85][86][87][88][89][90]. Because most of the reactions are not likely to occur through either a direct metal-mediated C

Cationic oligonucleotide derivatives and conjugates: A favorable approach for enhanced DNA and RNA targeting oligonucleotides

• Mathias B. Danielsen and
• Jesper Wengel

Beilstein J. Org. Chem. 2021, 17, 1828–1848, doi:10.3762/bjoc.17.125

• -dimethylamino)ethoxy)ethyl) monomer 39 has been prepared and shown to moderately enhance RNA affinity and induce high nuclease resistance, similar to that of modification 34 [79]. Optimizing the triplex stability of complexes formed between modified TFOs and their dsDNA target is an important direction of

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• natural abundance, cost-effectiveness, and low toxicity. In addition, it presents variable oxidation states (−3 to +7), which enable diverse catalytically active manganese complexes, providing characteristic reaction profiles. Since the first pioneering manganese-mediated reaction for accessing

• multiple steps to prepare suitable high-valent Mn complexes. Furthermore, Mn(I)-catalyzed enantioselective C–H functionalization at the late stage is still underexplored. Given the sustainability and versatility of manganese-catalyzed late-stage functionalization, further advances are expected in the

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

• Girish Suresh Yedase,
• Sumit Kumar,
• Jessica Stahl,
• Burkhard König and
• Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

• acting as the terminal oxidant [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Most aerobic oxidation reactions utilize either metal complexes and nanoparticles or persistent radical reagents as catalysts [21]. In the past ten years, visible light-induced

• mixing the (n-Bu4N)2CeIVCl6 complex with BnOH under basic conditions. The UV–vis spectra of the CeIV(OBn)Cln complex displayed a band resembling the LMCT band of known cerium–alkoxide complexes, showing considerable overlap with the blue LED region, thus suggesting that the CeIV(OBn)Cln species could be

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• amide linkages, to form strong and sequence specific complexes with natural DNA and RNA [3]. As will be discussed below, despite extensive studies [4][5][6], relatively few modifications have improved this simple original design. Since its inception, PNA has become an extremely useful research tool and

• involving PNA usually follow the order PNA–PNA > PNA–RNA > PNA–DNA [20][21]. Hybridization of PNA with complementary nucleic acids is enthalpy driven, involving large favorable gains in enthalpy compensated by significant unfavorable entropy, as typically observed for nucleic acid complexes [22]. The

• binding mode was also affected by PNA’s sequence with thymine-rich PNAs generally preferring invasion complexes and cytosine-rich PNAs generally preferring triple helix formation [25]. Overall, while PNA formed stronger triple helices with dsDNA than negatively charged oligonucleotides, the stability of

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• prepared by Ru-catalyzed [3 + 2]-cycloaddition of ynoate esters 170 with azide to produce metal-bound heterocyclic complexes 171 via an intramolecular cycloaddition reaction. The ynoate esters including diethyl acetylenedicarboxylate, ethyl 4,4,4-trifluoro-2-butynoate, methyl phenylpropiolate, and ethyl 2

• -butynoate successfully generated the metal-bound heterocyclic complexes. The alkylation reaction of 171a led to the bond cleavage between ruthenium and nitrogen to produce several 1-alkylated 4,5-bis(ethoxycarbonyl)-1,2,3-triazoles 172 [66]. Herein, the sodium azide initially reacts with [Ru]–Cl 168 to

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• , numerous hydroalkylation methodologies have emerged that have explored the diverse reactivity patterns of the olefin double bond. This review presents examples of olefins acting as electrophilic partners when coordinated with electrophilic transition-metal complexes or, in more recent approaches, when used

• counterparts, and so therefore are examples of quaternary centers generated by this means. The tendency of σ-alkylpalladium complexes to undergo a β-hydride elimination process is the major obstacle associated with the development of successful methodologies to promote intermolecular hydroalkylation of

• . Cationic gold(I) complexes are also suitable catalysts for olefin functionalization, and their use has become more popular than gold(III) catalysis [39]. In 2007, Che and Zhou reported the olefin intramolecular hydroalkylation of N-alkenyl β-ketoamides 13 using the gold(I)–phosphine complex Au[P(t-Bu)2(o

Free-radical cyclization approach to polyheterocycles containing pyrrole and pyridine rings

• Ivan P. Mosiagin,
• Olesya A. Tomashenko,
• Dar’ya V. Spiridonova,
• Mikhail S. Novikov,
• Sergey P. Tunik and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2021, 17, 1490–1498, doi:10.3762/bjoc.17.105

• complexes, Au(I) [20], Ir(III) [21] and Eu(III) [22] (Scheme 1). According to the calculations, the isomeric pyrido[2,1-a]pyrrolo[3,4-c]isoquinoline system B (Scheme 1) should have no less interesting photophysical properties [17], than skeleton A but its synthesis is still a challenge. In particular

• ). It is important that the reaction of iodide 1m with 2-pyridyl substituent gave a good yield of the product 3m, which could be used for the preparation of bidentate ligand for metal complexes. Reaction of salts 1 with electron-donating para-substituents (Me, MeO, Me2N) in the pyridine ring (1n–p,s

Antiviral therapy in shrimp through plant virus VLP containing VP28 dsRNA against WSSV

• Santiago Ramos-Carreño,
• Ivone Giffard-Mena,
• Jose N. Zamudio-Ocadiz,
• Alfredo Nuñez-Rivera,
• Ricardo Valencia-Yañez,
• Jaime Ruiz-Garcia,
• Maria Teresa Viana and
• Ruben D. Cadena-Nava

Beilstein J. Org. Chem. 2021, 17, 1360–1373, doi:10.3762/bjoc.17.95

• ). The procapsids and CP-dsRNA complexes obtained after dialysis in assembly buffer (pH 7.2) can be observed in images a and b (Figure 2A). After the second dialysis in virus buffer (pH 4.5), well-defined VLPs were formed (Figure 2A, c, and d). Finally, the dialyzed sample is shown in Figure 2A, e, and f

• formation and CP-dsRNAi complexes (Figure 2A, images a and b). The Gaussian fit size distribution of the spherical procapsids gave an average diameter of 21.2 nm and corresponded to capsids with triangulation number T = 2. The sample’s dialysis at pH 7.2 favors the electrostatic interactions between CCMV CP

• -dsRNA to form procapsids and CP-RNA complexes [42]. The dsRNA negative charges can be neutralized by the positive N-terminal protein in these procapsids [42]. However, procapsids are not suitable for any treatment because they do not efficiently protect their cargo. The dsRNA in the procapsids may be

Heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile: synthesis of diverse nitrogenous heterocyclic compounds

• Guanglong Pan,
• Qian Yang,
• Wentao Wang,
• Yurong Tang and
• Yunfei Cai

Beilstein J. Org. Chem. 2021, 17, 1171–1180, doi:10.3762/bjoc.17.89

• ). Traditional g-C3N4 exhibited a low catalytic activity for this transformation (Table 1, entry 6). Switching from CN-K to a homogeneous organo photocatalyst such as eosin Y and 4CzIPN, led to lower yields of the desired product (Table 1, entries 7 and 8). The expensive Ru/Ir-based metal complexes gave similar

Structural effects of meso-halogenation on porphyrins

• Keith J. Flanagan,
• Maximilian Paradiz Dominguez,
• Zoi Melissari,
• Hans-Georg Eckhardt,
• René M. Williams,
• Dáire Gibbons,
• Caroline Prior,
• Gemma M. Locke,
• Alina Meindl,
• Aoife A. Ryan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2021, 17, 1149–1170, doi:10.3762/bjoc.17.88

• ][12][13]. Such complexes have been reported for potential application in materials sciences (e.g., molecular sieves) as they form a three-dimensional lattice where more than 50% of the crystal capacity consists of open straight channels [5][6]. Noteworthy, Titi et al. reported that a chiral

• and combined with NSD analysis to approximate the IP and OOP distortion modes. The wB97XD functional was chosen because it has been shown to produce reliable energy minimized structures for organometallic complexes and metalloporphyrins [42][43][44]. With the first series (series 1) we looked at the

• complexes rather than direct interactions and alkyl moieties form a plethora of halogen···hydrogen interactions. Additionally, the substitution pattern greatly affects the overall conformation. By comparing the DFT calculated geometries with crystal structures we have found that DFT is a good approximation

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• given combination of enone and arylboronic acid. Keywords: asymmetric reaction; boronic acid; conjugated enones; chromones; enantioselective catalysis; Michael addition; Pd complexes; Introduction The asymmetric 1,4-addition of arylboronic acids to conjugated cyclic enones and chromones is a very

• important reaction nowadays. For illustration, the addition products are very promising in medicinal chemistry research [1][2][3][4][5][6][7] and in natural products total syntheses [8][9][10][11][12][13][14][15][16]. Chiral complexes of Rh [17][18][19][20][21][22][23][24] and Pd usually catalyse the

• %; 85% ee), but the reaction times were very short (Scheme 7) [41]. In 2011, the groups of Hayashi and Chujo studied Pd complexes of diphosphacrown ethers [42]. The macrocyclic Pd complex PdL5 in combination with AgSbF6 or AgOTf was tested for the addition reaction of various arylboronic acids to 2

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• such as lead tetraacetate, potassium permanganate, or refluxing hydrogen peroxide were shown to produce urea-derived degradation products [3]. Biguanides also possess a remarkable capability to form stable metal complexes, a property that was already noticed by B. Rathke in 1879 [4]. Indeed, he relied

• on this feature to isolate biguanide as a copper complex. Interestingly, transition metal-biguanide complexes often present vivid colors because of a strong absorption in the visible range. Biguanides have been used in chemistry as versatile starting materials in organic synthesis, catalysts [5

• transesterification of several vegetable oils [5]. Since the first reported copper-biguanide complex, the synthesis of a variety of stable biguanide complexes has been reported with VIV, CrIII, MnIII, MnIV, CoII, CoIII, NiII, CuII, ZnII, PdII, ReV, OsVI [8], etc. Many of these complexes found applications as

Manganese/bipyridine-catalyzed non-directed C(sp³)–H bromination using NBS and TMSN₃

• Kumar Sneh,
• Takeru Torigoe and
• Yoichiro Kuninobu

Beilstein J. Org. Chem. 2021, 17, 885–890, doi:10.3762/bjoc.17.74

• -position of an oxazoline or amide is selectively activated using a copper or palladium catalyst. Manganese is one of the most abundant and nontoxic transition metals found in the earth’s crust and its corresponding complexes and salts are useful in synthetic organic reactions [29][30][31][32][33][34][35

Highly regio- and stereoselective phosphinylphosphination of terminal alkynes with tetraphenyldiphosphine monoxide under radical conditions

• Dat Phuc Tran,
• Yuki Sato,
• Yuki Yamamoto,
• Shin-ichi Kawaguchi,
• Shintaro Kodama,
• Akihiro Nomoto and
• Akiya Ogawa

Beilstein J. Org. Chem. 2021, 17, 866–872, doi:10.3762/bjoc.17.72

• bidentate diphosphine ligands having a rigid structure and has increased attention as a useful and effective ligand in coordinating with various metals [19][20]. (Z)-Ph2PCH=CHPPh2 is very important as a bidentate ligand for many mononuclear complexes [21][22][23]. On the other hand, (E)-Ph2PCH=CHPPh2 acts

• as a monodentate ligand for mononuclear complexes, but it is highly attractive because a hierarchical structure can be constructed by cross-linking between two metals [24][25][26]. Considering the characteristics of the coordination form between the (E)- and (Z)-isomers, the development of a

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

A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson’s reagent

• Ke Wu,
• Yichen Ling,
• An Ding,
• Liqun Jin,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2021, 17, 805–812, doi:10.3762/bjoc.17.69

• incomparable chelating ability towards selected transition metals, and the corresponding complexes were applied in various areas such as chemical-sensor materials, tunable redox-potential complexes, polymer hybrid luminescence materials, building blocks for multinuclear complexes, and as catalysts for cross