Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

• Tülay Yıldız,
• İrem Baştaş and
• Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

• ]. Therefore, there has been an increase in arylation methods using Friedel–Crafts alkylation (FCA) protocols without transition metals [35][36]. Environmentally friendly methods, in which metal-free catalysts are used, have come to the fore and are gaining importance because there are many disadvantages of

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

• equally effective catalysts. First-row transition (3d) metals have shown to be important catalysts in this matter. This review summarizes the use of 3d metal catalysts in C–H activation processes to obtain potentially (or proved) biologically active compounds. Keywords: bioactive compounds; C–H

• activation; 3d metals; drugs; medicinal chemistry; Introduction The discovery of new biologically active substances represents not only an advance in the chemistry field but also offers innovative chances for pharmacological and biomedical sciences. Every year, several molecules are discovered and studied

• synthetic methodologies is the C–H bond activation process that enables a straightforward access to several important and innovative compounds [14][15][16][17][18]. In the last few years, metals such as ruthenium [19][20][21], rhodium [22][23][24], palladium [25][26][27], and iridium [28][29][30] have been

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

• powerful synthetic strategy for accessing advanced agrochemicals, bioimaging materials, and drug candidates, among other complex molecules. While traditional late-stage diversification relies on the use of precious transition metals, the utilization of 3d transition metals is an emerging approach in

• organic synthesis. Among the 3d metals, manganese catalysts have gained increasing attention for late-stage diversification due to the sustainability, cost-effectiveness, ease of operation, and reduced toxicity. Herein, we summarize recent manganese-catalyzed late-stage C–H functionalization reactions of

• biologically active small molecules and complex peptides. Keywords: bioactive molecules; 3d transition metals; late-stage functionalization; manganese catalyst; sustainable catalysis; Introduction Manganese, a 3d transition metal, allows for a potentially ideal sustainable catalytic system because of the

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

• nucleophiles, along with transition-metal catalysis, in olefin alkylation reactions [18][19][20][21]. Apart from the early examples of olefin functionalization with transition metals, such as the well-known ethylene oxidation catalyzed by Pd(II) (the Wacker reaction) [23][24], the use of carbon nucleophiles in

• further demonstrated by the hydroalkylation of the anti-inflammatory drug phenylbutazone (7j). Gold(I)/gold(III) and silver(I) catalysis in olefin hydroalkylation The early limitations associated with Pd catalysis in olefin hydroalkylation reactions prompted the search for alternative metals for olefin

One-step synthesis of imidazoles from Asmic (anisylsulfanylmethyl isocyanide)

• Louis G. Mueller,
• Allen Chao,
• Embarek AlWedi and
• Fraser F. Fleming

Beilstein J. Org. Chem. 2021, 17, 1499–1502, doi:10.3762/bjoc.17.106

• etomidate [4] and the antileukemia agent nilotinib [5]. The outstanding and diverse bioactivity of imidazole-containing pharmaceuticals [6], as well as their role as ligands for transition metals [7], and organocatalysis [8], has stimulated an array of creative syntheses [9][10]. Among the numerous routes

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

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

• cyanomethylarylation of alkenes, most of them rely on the use of transition metals (such as catalytic amounts of Pd, Cu, Fe catalyst or stoichiometric amounts of Ag, Mn salts) and strong oxidants (including PhI(OPiv)2, DTBP, and t-BuONO) in the presence of various base additives under high reaction temperatures or

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

• allylic bromides in the presence of zinc or indium metals is a well-known reaction [66][67]. It is possible to control and predict the stereochemistry of the addition to get the corresponding homoallylamine derivative with a high level of stereocontrol. The reaction of chiral imine 14 with an excess of

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

• satisfying 57% yield (Scheme 31A) [68]. Furthermore, the formation of this byproduct was particularly promoted in the case of hindered amines such as diisopropylamine and dicyclohexylamine. Recently, to study the complexation properties of N-amidino-amidinopyrazole with transition metals, its synthesis was

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

• , often heavy metals; (2) multiple additives (co-promoter, molecular sieves, acid scavenger) to facilitate the reaction and/or suppress formation of side-products; (3) low temperatures; (4) complex experimental procedures. Additionally, the majority of the methods reported to date have been applied only

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

• 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

• 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

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• . Catalysis is the next area that is gaining an ever-increasing practical focus in the studies on the use of C60 and fullerene-containing materials [51]. A comparative analysis of the activity of fullerene-containing compounds and noble metals as dehydrogenation catalysts allows to consider the former as

• alternatives that favorably differ in cost. However, the efficiency is similar to the functional analogs of catalytic additives based on noble metals [52]. The presence of metal–fullerene chemical bonding results in catalysts that reliably provide high process selectivity due to the simultaneous adsorption of

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• standard EN 13432 “Packaging–Requirements for packaging recoverable through composting and biodegradation” include disintegration (i.e., breakdown of material to particles of a defined size), biodegradability, absence of negative effects on the composting process and amount of heavy metals below given

• , wherein acetates, phosphates and chlorides of heavy metals (Ti, Zn, Mg, Co, Fe) or lead oxide are commonly used in the alcoholysis and glycolysis of polyesters [127][128]. Despite that these systems ensure high conversions and selectivity, shortcomings relate to the harsh reaction conditions, slow

• kinetics, cost of metals, toxicity, difficulty in catalyst reusing and need of downstream processing. Significant efforts have thus been made to develop greener and sustainable catalytic systems featuring high efficiency under mild conditions. The use of sodium carbonate or bicarbonate as ecofriendly

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

• Lucía Rossi-Fernández,
• Viviana Dorn and
• Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

• have been developed, most of them using expensive or scarce metals (Au or Pd [18][19][20][21], groups IV and V metal oxides [22][23]) and mainly through homogeneous catalytic processes [24][25][26]. From a practical, economic and environmental point of view, reusable heterogeneous catalysts based on

• earth-abundant transition metals are much more attractive, especially for industrial applications [27][28]. In recent years, many efforts have been made in finding new catalytic systems based on the use of low cost and abundant non-noble metals, and much attention have been paid to the development of Fe

• , Mn and mainly Co-based catalysts for olefin epoxidation. Besides their low cost and low toxicity, the choice of these metals is related to their known ability to activate dioxygen in natural processes catalyzed by metal-containing enzymes [29][30]. Despite that various homogeneous [31][32] and

Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands

• Sergey V. Norkov,
• Anton V. Cherkasov,
• Andrey S. Shavyrin,
• Maxim V. Arsenyev,
• Viacheslav A. Kuropatov and
• Vladimir K. Cherkasov

Beilstein J. Org. Chem. 2021, 17, 273–282, doi:10.3762/bjoc.17.26

• coordination ability. The redox state of o-quinone (semiquinone or catechol) could be changed both as free species or when it is coordinated to a metal ion as a ligand. Thus, the redox isomerism phenomenon was reported for o-quinone complexes with both transition and non-transition metals [1][2][3]. The

• ). The values of coupling constants with these protons vary in the range of 0.18–0.30 G, they are highly sensitive to the nature of the metallofragment at the chelating dioxolene site. With metals tending to high ionicity in the bonding with the ligand we observed smaller values of coupling constants. o

• and CF3 groups are omitted for clarity. Synthetic pathways for the preparation of o-quinone derivatives with annulated 1,3-dithiole ring. The tentative pathway for the formation of o-quinone 7 with annulated thiete ring. Reactions of o-quinone 6a. Stepwise reduction of o-quinones with metals to

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• -valent transition metals such as Pd(0) also have a valuable catalytic role, particularly because of their ability to participate in oxidative addition reactions and to form π-allyl complexes. In the absence of nucleophiles, homolysis of the distal C–C bond takes place under the effect of high temperature

Selective synthesis of α-organylthio esters and α-organylthio ketones from β-keto esters and sodium S-organyl sulfurothioates under basic conditions

• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Thiago Barcellos,
• Claudio C. Silveira and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2021, 17, 234–244, doi:10.3762/bjoc.17.24

• , and related compounds. Some of them are catalyzed by expensive transition metals, such as gold, iridium, palladium, and titanium. More recently, the selective formation of C–S bonds using 1,3-dicarbonyl compounds, followed by a C–C bond cleavage has emerged as a versatile and less expensive protocol

Au(III) complexes with tetradentate-cyclam-based ligands

• Ann Christin Reiersølmoen,
• Thomas N. Solvi and
• Anne Fiksdahl

Beilstein J. Org. Chem. 2021, 17, 186–192, doi:10.3762/bjoc.17.18

• range of other transition metals. The utilization of gold in synthetic organic chemistry has become a topic of interest during the last decades, as evidenced by the increasing number of review articles published in this period [1][2][3][4][5][6][7][8]. Whereas both gold(I) and gold(III) are proven to be

• binding properties [25] and reactions with bovine serum albumin [27]. Cyclam is known as a tetraamino-macrocyclic ligand, which binds strongly to give complexes with many transition metal cations. While catalytic applications of square planar cyclam complexes are reported for metals, such as Ni [30][31

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• a stabilizer to control the size and distribution of the NPs and are able to intensely regulate the photocatalytic performance. 5) To improve the sustainability, noble metals need to be replaced by earth-abundant metals. However, in most cases, earth-abundant metals have a lower photocatalytic

• activity compared to noble metals in supramolecular materials. Therefore, there is an urgent demand to search for earth-abundant metals with a high activity. In conclusion, investigations on macrocycle-based catalysis are still needed to effectively extend their potential applications to solve chemical

An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp³)–H bond functionalization under solvent- and catalyst-free conditions

• Divya Rohini Yennamaneni,
• Vasu Amrutham,
• Krishna Sai Gajula,
• Rammurthy Banothu,
• Murali Boosa and
• Narender Nama

Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259

• years, C−H bond functionalization catalyzed by transition metals received a strong emphasis, and other different catalytic systems have also been encouraged [16][17][18][19][20]. Huang and co-workers first realized the addition of alkylazaarenes directly to unsaturated bonds via C(sp3)–H

• , Yaragorla et al. published a review on C(sp3)–H bond functionalization of 2-methylazaarenes [39]. These strategies are proficient, but due to the involvement of drastic reaction conditions, the use of expensive reagents, toxic metals, harmful solvents, and tedious workup procedures, they need to be

Controlled decomposition of SF₆ by electrochemical reduction

• Sébastien Bouvet,
• Bruce Pégot,
• Stéphane Sengmany,
• Erwan Le Gall,
• Eric Léonel,
• Anne-Marie Goncalves and
• Emmanuel Magnier

Beilstein J. Org. Chem. 2020, 16, 2948–2953, doi:10.3762/bjoc.16.244

• reactive, corrosive and toxic [12]. Recent and really impressive works were devoted to the decomposition of sulfur hexafluoride using stoichiometric or catalytic amounts of metals (Rh, Ni, Pt) [13][14][15][16]. Organic derivatives (phosphines or bipyridine) proved efficient tools for the selective