DABCO-promoted photocatalytic C–H functionalization of aldehydes

• Bruno Maia da Silva Santos,
• Mariana dos Santos Dupim,
• Cauê Paula de Souza,
• Thiago Messias Cardozo and
• Fernanda Gadini Finelli

Beilstein J. Org. Chem. 2021, 17, 2959–2967, doi:10.3762/bjoc.17.205

• is reduced by the photocatalyst (PC−) after coordination to aryl bromide, promoting the turnover of organometallic and photoredox cycles. DABCO is regenerated via deprotonation by an inorganic base. We also investigated the mechanism operating when the reaction is performed in the absence of bicyclic

Study on the interactions between melamine-cored Schiff bases with cucurbit[n]urils of different sizes and its application in detecting silver ions

• Jun-Xian Gou,
• Yang Luo,
• Xi-Nan Yang,
• Wei Zhang,
• Ji-Hong Lu,
• Zhu Tao and
• Xin Xiao

Beilstein J. Org. Chem. 2021, 17, 2950–2958, doi:10.3762/bjoc.17.204

• , are formed by polymerization of glycoluril, which contains rigid cavities for the study of host–guest chemistry and carbonyl groups for the study of coordination chemistry [16][17][18][19][20]. For the special methyl cucurbit[n]urils with abundant methyl groups, its high density of the

• Schiff base reaction and the nucleophilic reaction of haloalkane (Scheme 1 and Supporting Information File 1, Scheme S1) [25]. In addition to retaining the abundant coordination sites of Schiff bases, TBT is also modified with carbon chains of appropriate length for inducing host–guest interactions and

• coordination ability to metals. In this study, Q[7]-TBT was selected as a UV detector to detect common metals. As shown in Figure 5, the additional Ag+ increases the absorbance of the Q[7]-TBT complex from 0.441 to 0.555 at λmax = 258 nm, while other metal ions do not increase or decrease the absorbance

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• borylmetallation across the alkene in a syn-fashion 58. Side-on coordination of the haloalkene’s π-bond can trigger a syn-carbometallation 59. A base-mediated 1,2- elimination will deliver the alkenylboration product as well as regenerate 56. The methodology was applied towards the synthesis of (±)-imperanene

Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions

• Qingkai Zeng,
• Qiumeng Long,
• Jihong Lu,
• Li Wang,
• Yuting You,
• Xiaoting Yuan,
• Qianjun Zhang,
• Qingmei Ge,
• Hang Cong and
• Mao Liu

Beilstein J. Org. Chem. 2021, 17, 2840–2847, doi:10.3762/bjoc.17.195

• . Hemicucurbit[n]urils (HQ[n]) and relevant derivatives [24] represent as a sub-group of the cucurbituril family [25], possessing much more flexible structures than Q[n]s, and are generally characterized by an electroneutral cavity and a negative electro-potential portal. Comparing the coordination properties of

• as reactive sites for derivatization, at the same time allowing for formation of coordination or hydrogen bonds with guests, and the aminobenzene unit as a chromophore could improve the optical properties. With this novel macrocycle in hand, the interactions with some metal cations have been

• −, and ClO4− (tetrabutylammonium salts were used as anion source) were also tested tentatively by fluorescence titration (Figure 5). The overwhelming majority of aromatic molecules follow the heavy-atom effect rule [48]. However, it was surprisingly found that the coordination of selected anions, such as

Biological properties and conformational studies of amphiphilic Pd(II) and Ni(II) complexes bearing functionalized aroylaminocarbo-N-thioylpyrrolinate units

• Samet Poyraz,
• Samet Belveren,
• Sabriye Aydınoğlu,
• Mahmut Ulger,
• Abel de Cózar,
• Maria de Gracia Retamosa,
• Jose M. Sansano and
• H. Ali Döndaş

Beilstein J. Org. Chem. 2021, 17, 2812–2821, doi:10.3762/bjoc.17.192

• rotation of the thioketone carbon–N-pyrrolidine bond, are energetically accessible, in agreement with the two set of signals observed by 1H NMR spectroscopy (energy differences between conformers lower than 1 kcal·mol–1 in both cases). However, this equilibrium is strongly affected by the coordination to

• nickel or palladium atoms. As far as the L1-Ni complex was concerned, this fluxional equilibrium disappeared due to metal coordination. In this case, complexes involving conformer B were highly energetic due to steric repulsion between the CO2Me substituents of the pyrrolidine ring. Thus, only one set of

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• . Funding We would like to thank the following entities: The Coordination for Improvement of Higher Education Personnel (CAPES/PROEX – Finance Code 001) for the fellowships, and the National Council for Scientific and Technological Development (CNPq) (grants process Grants no. 305.379/2020-8) and the

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• 16 via β-H elimination using (S)-CPA 4 as a ligand (Scheme 7) [51]. The directing group (NH2) facilitated the C–H activation on the other aromatic ring and ensured its coordination with Pd to form palladacycle I-2 to restrict bond rotations and promote exclusive allylic selectivity via β-H1

AlBr₃-Promoted stereoselective anti-hydroarylation of the acetylene bond in 3-arylpropynenitriles by electron-rich arenes: synthesis of 3,3-diarylpropenenitriles

• Yelizaveta Gorbunova,
• Dmitry S. Ryabukhin and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2663–2667, doi:10.3762/bjoc.17.180

• oligomeric material was obtained and the yield of the target reaction product 2a was lower (20%) than in the same reaction with AlBr3. This result revealed the less effectiveness of AlCl3 for the hydroarylation of nitriles 1. One may propose the following reaction mechanism (Scheme 2). The coordination of

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• )- and (S,S)-C2 (Figure 2a) have anti-syn arrangement of the urea unit. Figure 2b shows the enamine intermediate likely formed between aldehyde 6c and catalyst (S,R)-C2. The urea unit adopts an anti-anti arrangement upon coordination of a nitroalkene via hydrogen bonds (Figure 2c). The reaction likely

• proceeds via initial enamine formation from the aldehyde and catalyst. The coordination of the nitroalkene via hydrogen bonding with the (thio)urea moiety will bring it in the vicinity of the enamine from the re-face. The major enantiomer of the Michael adduct (S,S)-10 is formed via re-attack on the

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• ), which was due to the ability of copper to stabilize and interact with radical intermediates in its coordination sphere. Mechanistic studies revealed that the iodoperfluoroalkylation of alkenes and alkynes involved a rebound or ligand transfer cycle (section 3.1). In 2017, Wang and co-workers [54

• (sp2)–H bonds of azoles was developed by Zhang [89]. A 2,2’-bipyridine copper coordination compound served as the photoredox catalyst and accomplished the azole C–H arylations. Under irradiation with blue LED, the photoexcited state [LnCuI-benzoxazole]* (C) engages in a double electron-transfer process

• -CuII superoxo complexes A. Under light irradiation, complex A produces the excited-state ligand-CuII superoxo complex A*, which undergoes coordination with the aliphatic alcohol to form complex B. The latter initiates the oxidation reaction and transfers a hydrogen atom from α-C(sp3)–H of the alcohol

Copper-catalyzed monoselective C–H amination of ferrocenes with alkylamines

• Zhen-Sheng Jia,
• Qiang Yue,
• Ya Li,
• Xue-Tao Xu,
• Kun Zhang and
• Bing-Feng Shi

Beilstein J. Org. Chem. 2021, 17, 2488–2495, doi:10.3762/bjoc.17.165

• excellent mono-selectivity and no diaminated ferrocenylamide was detected. The exclusive monoselectivity is most likely originated from the strong coordination of the amino group, which could form a tridentate copper complex and prevent the second C–H amination [34][50]. Having obtained the optimized

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• propargyl acrylate (Alk-4), the rate of clicking slightly decreased in the case of propargylamine (Alk-2), but still gave high yields. Therefore, it can be concluded that Alk-2 and Alk-1 exhibit relatively lower efficiency probably due to the additional coordination of the CuI catalyst. Notably, the

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

• anion coordination and supramolecular chemistry [7][8][9][10][11], this field of research has attracted more attention within the past two decades. Immense efforts were made to identify small molecules that are able to productively bind anions via noncovalent hydrogen bonding, from which cationic

• compounds are coordinated to the H-bond catalyst, whereas anion-binding catalysis relies on the formation of an ion pair by binding to the counter-anion of an ionic substrate. The ionization of the corresponding substrate can either occur before the coordination to the anion or the catalyst itself directly

• design of more efficient H-donor catalyst structures, offering additional noncovalent interactions in order to provide extra coordination points with the anion, substrate and/or reagent. The most important approaches in this direction used to date are presented in the following. (Thio)urea and squaramide

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

• 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

• twentieth most abundant element and the sixth most abundant transition metal in Earth’s crust. Rarely encountered in its metallic form, vanadium exists in oxidation states ranging from +5 to −3, including the four adjacent states +2 to +5 in aqueous solutions, and usually presents 4, 5 or 6 coordination

• manganese is 3d54s2 with a high redox potential due to the high number of available oxidation states (−3 to +7), allowing the formation of compounds with a coordination number of up to 7 [127]. These properties associated with a low toxicity and low cost make manganese a metal with great potential in

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

• -carboxamides. The reaction includes oxidative addition of 5-iodo-1,2,3-triazole 117 to a Pd center to achieve the intermediate 120. The intermediate 121 is formed via coordination and insertion of CO to intermediate 120. Then, the intermediate 122 is obtained via a nucleophilic attack of amine 118. Finally, a

Copper-mediated oxidative C−H/N−H activations with alkynes by removable hydrazides

• Feng Xiong,
• Bo Li,
• Chenrui Yang,
• Liang Zou,
• Wenbo Ma,
• Linghui Gu,
• Ruhuai Mei and
• Lutz Ackermann

Beilstein J. Org. Chem. 2021, 17, 1591–1599, doi:10.3762/bjoc.17.113

• observed by parallel experiments, again suggesting that the C‒H activation is kinetically relevant (Scheme 4d). Based on our mechanistic findings and previous studies, we propose a tentative plausible reaction pathway in Scheme 5. The transformation commences with substrate coordination and subsequent

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

• expense of the olefin double bond. Review Olefin activation by transition metals Transition metals can act as π-acid catalysts in olefin double bond activation, as they weaken the alkene double bond through coordination to allow a nucleophilic attack on the sp2 carbon to form an alkylmetal intermediate

• , suggesting that the coordination and proton-shuttle ability of the anionic counterion were the main factors responsible for the observed effects. The proposed mechanism (Scheme 10) begins with the activation of the gold(I) pre-catalyst by the exchange of a chloride anion with a non-coordinated one (Y−) to

• suggested that iridium serves as a π-Lewis acid (although one could propose a C–H activation pathway) that activates the olefin by coordination due to the correlation observed between the nature of the Ir counterion and the reaction yields. Radical-based approaches Olefin hydroalkylation via metal hydride

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

• ‘guests’ within the crystal lattice, through hydrogen-bonding and van der Waals forces. Thereafter, research over the crystal engineering of porphyrins has focused on the noncovalent interactions, such as hydrogen bonds and halogen bonds, or metal coordination interactions [2][3][4][5][6][7][8][9][10][11

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• crystallographic analysis, and it was found that the configuration of the newly generated stereocenter was R. Huang and co-workers proposed a cyclic transition state determined by the coordination of the nitrogen of the imine, and the oxygen atoms of the sulfoxonium and sulfinyl units to the sodium cation, which

Synthesis of multiply fluorinated N-acetyl-D-glucosamine and D-galactosamine analogs via the corresponding deoxyfluorinated glucosazide and galactosazide phenyl thioglycosides

• Vojtěch Hamala,
• Lucie Červenková Šťastná,
• Martin Kurfiřt,
• Petra Cuřínová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2021, 17, 1086–1095, doi:10.3762/bjoc.17.85

• coordination of ZnI2. When the α-anomer of thioglycoside 17 was separately subjected to the reaction conditions, the byproduct 20 started to form in trace amounts in accordance with the suggested mechanism. The ring contraction may involve formation of a transient oxiranium cation as suggested in Scheme 2 [42

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

• oxidative Heck-type product. The authors stated that as a result of the coordination with PPh3, there is a steric hindrance disfavouring the β-hydride elimination [43]. Catalytic systems based on NHC ligands Historically, the second type of ligands used were N-heterocyclic carbenes (NHC). The first use was

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

• -driven research led to a large production of standard every-day drugs with antidiabetic, antiseptic, and even anticancer properties. Recently, biguanides have gained particularly increasing attention in several areas, such as drug design, coordination chemistry, and materials science [1]. In this context

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• performed on the model reaction α-11 + MeOH → α-13c to elucidate the influence of SO2 on the dissociation of the glycosidic C–F bond [78] (Figure 2). Indeed, it was found that the coordination of the Lewis acidic SO2 to the fluoride (transition state TS-A≠ versus TS-A(SO2)≠) decreases the C–F bond

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

• compounds in catalytic technologies, biochemistry, and materials [1][2][3][4][5][6]. In particular, in coordination chemistry and catalyst chemistry, organophosphorus compounds such as triorganylphosphines are widely used as typical monodentate ligands for many metals [7][8]. In addition, diphosphines such

• 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