Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• oxidative conditions, catalyzed by CuTC to give the desired product 101 (Scheme 15a). On the other hand, Yang synthesized bis(indol-3-yl)sulfides 105 through the reaction of indole with elemental sulfur, catalyzed by iron(II) sulfate in the presence of stoichiometric amounts of KI in air [83]. The I− from

• KI formed ferrous iodide, which reacts with indole to form the iron bis-indolide 107, followed by reaction with N,N-dimethylmethanethioamide to get the S atom inserted (108). A reductive elimination then generated the bis(indol-3-yl)sulfides 105 along with Fe0, which was re-oxidized by aerial oxygen

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

• could help expanding the currently available methods in organic synthesis. Manganese-catalyzed C–H activation Manganese is the twelfth most abundant element in the Earth’s crust and the third most abundant transition metal after iron and titanium [126]. The valence electron configuration of elemental

• increase the chance of finding plausible new drugs, with potent activities. Iron-catalyzed C–H activation By mass, iron is the most abundant metal on Earth. Therefore, it has been and still is widely used in many fields, from ancient but still applicable appliance as feedstock to construct basic steel

• tools [148], to the most recent nanotechnology field [149]. Iron presents powerful catalyst properties [150][151][152], including applications in C–H activation reactions [153][154][155]. In 2007, White and Chen reported a seminal work regarding predictably selective aliphatic C–H oxidations by using an

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

• [49]. To date, there are several examples of late-stage C–H amination methods that utilize iron and manganese as 3d transition metal catalysts [50][51][52]. However, intermolecular benzylic C–H amination has rarely been explored due to the challenges associated with selectivity and reactivity. In 2018

• protein–ligand binding properties as well as biological activities of small molecules, potentially leading to dramatic increases in potency, and thus has been widely explored in drug discovery [54][55][56]. Late-stage C–H methylation has recently been investigated using iron and cobalt catalysts as

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

• -coordinating anion OCl− and as an activator of the gold(I) complex in these reactions. Other metals Although gold catalysis predominates in these types of reactions, inexpensive iron salts have also been employed successfully in hydroalkylation reactions. In 2007, Beller and co-workers reported the

• hydroalkylation of styrenes 9 using FeCl3·H2O as a source of iron(III) (Scheme 13) [46]. This reaction required higher temperatures than those used in the gold(III) methodology reported previously by Li [38] and a considerable excess (10 equiv) of alkenes (Scheme 6) to achieve the products in practice yields

Recent advances in the application of isoindigo derivatives in materials chemistry

• Andrei V. Bogdanov and
• Vladimir F. Mironov

Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111

• also found that a device based on compound 45 (R = 2-decyltetradecyl) with the addition of iron phthalocyanine showed slightly better mobility. Liu et al. explain this effect by an improvement in the hole-type conductivity and a tight and even packing of the composite in a thin film [80]. At the same

Substituted nitrogen-bridged diazocines

• Pascal Lentes,
• Jeremy Rudtke,
• Thomas Griebenow and
• Rainer Herges

Beilstein J. Org. Chem. 2021, 17, 1503–1508, doi:10.3762/bjoc.17.107

• compounds with iron(III) to perform an intramolecular Baeyer–Mills reaction [15][21]. We found that a complete reduction of the nitro group to aniline 7 and oxidation with mCPBA is increasing the yield of the intramolecular cyclization from 39% to 62% (over two steps) for the unsubstituted diazocine 8c as

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

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

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• trans-THP. Feng and co-workers’ FeCl3-catalyzed Prins cyclization strategy to 4-hydroxy-substituted THP. Selectivity profile of the Prins cyclization under participation of an iron ligand. Sequential reactions involving Prins cyclization. Banerjee and co-workers’ strategy of Prins cyclization from

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

• , glycolysis of PET was performed under microwave heating in the presence of Zn(OAc)2, yielding BHET with an 80% selectivity at 97% conversion due to formation of dimers (Table 2, entry 7) [203][204]. Soluble metal chlorides (zinc, magnesium, iron, zirconium, cobalt, nickel) were also explored as catalysts in

Synthesis and physicochemical evaluation of fluorinated lipopeptide precursors of ligands for microbubble targeting

• Masayori Hagimori,
• Estefanía E. Mendoza-Ortega and
• Marie Pierre Krafft

Beilstein J. Org. Chem. 2021, 17, 511–518, doi:10.3762/bjoc.17.45

• , including dendronized iron oxide nanoparticles [38] and nanodiamonds [39]) efficiently reinforce the interfacial film cohesion, thus enhancing the stability of the MBs. Various types of perfluoroalkylated amphiphiles have been reported that were designed for biomedical applications and display highly

A heterobimetallic tetrahedron from a linear platinum(II)-bis(acetylide) metalloligand

• Matthias Hardy,
• Marianne Engeser and
• Arne Lützen

Beilstein J. Org. Chem. 2020, 16, 2701–2708, doi:10.3762/bjoc.16.220

• (acetylide)platinum(II) complex [Pt(L1)2(PBu3)2] as a linear metalloligand. The reaction of this metalloligand with iron(II) cations and pyridine-2-carbaldehyde according to the subcomponent self-assembly approach yielded decanuclear heterobimetallic tetrahedron [Fe4Pt6(L2)12](OTf)8. Thus, combination of

• trans-[Pt(PBu3)2Cl2] (2). The aniline moieties in 3 were further transformed into chelating pyridylimine binding sites in the following subcomponent self-assembly process when six equivalents of metalloligand 3 were reacted with twelve equivalents of pyridine-2-carbaldehyde and four equivalents of iron

• , showing a series of signals with different charge states that could be assigned to 4. The mass spectrum also shows that the cage easily fragments upon ESI, as additional signals a–d were detected. The successful formation of iron(II)-containing metallosupramolecular tetrahedron 4 could also be proven by

Synthesis of 4-substituted azopyridine-functionalized Ni(II)-porphyrins as molecular spin switches

• Jannis Ludwig,
• Tobias Moje,
• Fynn Röhricht and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2589–2597, doi:10.3762/bjoc.16.210

• ][23][24][25][26]. Hence, 3-iodonitrobenzene (4) was reduced to obtain hydroxylamine 5, which was oxidized by iron(III) chloride to yield a mixture of 6 and starting material 4 (Scheme 1), which was directly used as a crude product in the subsequent alkaline Baeyer–Mills reaction. It is known that the

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

• increased the apparent reaction rate by a 4-fold compared to an iron packing material [68]. Therefore, a translucent material should be preferred in photoreactors. The photon flux received by the absorbing species needs to be determined accurately in order to characterize photochemical reactors. The

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• reaction as the critical step [54]. Towards this goal, they started with the hexabromination of sumanene using bromine and iron powder in nitrobenzene to provide the desired compound 94 in 61% yield. Having the bromosumanene 94 in hand, it was then subjected to the Suzuki coupling with several arylboronic

• [CpRu(η6-sumanene)]PF6 126 along with its bowl-to-bowl inversion and anticipated it to be more flexible in comparison to the iron analogue 123a, may be due to the longer C–Ru bond (Scheme 32) [64]. The complex 126 was prepared in a similar manner as its iron analogue was prepared. Quite recently

• the hexabromination using Br2 and iron powder in PhNO2. The brominated derivative 157 was then converted to the hexathiolated trithiasumanenes 158a–c by substitution reaction (Scheme 41). The structures of these functionalized heterosumanenes were confirmed by spectroscopy as well as crystallography

Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate

• Mysore Bhyrappa Harisha,
• Pandi Dhanalakshmi,
• Rajendran Suresh,
• Raju Ranjith Kumar and
• Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2020, 16, 2108–2118, doi:10.3762/bjoc.16.178

• of iron salts and solventsa. Supporting Information Supporting Information File 518: Full experimental details, compound characterisation, and copies of NMR spectra. Funding M. B. H. is grateful to Eurofins-Advinus Limited, Bangalore for support. P. D. thanks the Science and Engineering Research

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

• (kaolinite) and iron oxides were also confirmed by the XRD pattern. The less intense diffraction peaks at 2θ = 12.3, 24.8, and 37.4 were assigned to the 001, 002, and 003 plane, respectively, of kaolinite (JCPDS card file 14-0164) [78]. The low-intense peaks at 2θ = 18.6, 26.1, 44.7, 54.6, 58.4, and 63.0

• were ascribed to the 111, 211, 400, 422, 511, and 440 plane, respectively, of iron oxides (JCPDS card file 39-1346 and JCPDS card file 19-629) [79][80]. The above results were supported by FTIR and Raman characterization studies of the catalyst (vide infra). The FTIR spectrum of the catalyst is shown

• bending vibrations of water [82]. The impurities aluminium silicate and iron oxides in the NDL were confirmed by IR spectroscopy. The peaks located at 446, 551, 817, 952, 1247, and 1383 cm−1 were attributed to the Si–O bending, Fe–O stretching, Al–O–Si stretching, Si–OH bending, Si–O stretching, and Al–O

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

4-Hydroxy-3-methyl-2(1H)-quinolone, originally discovered from a Brassicaceae plant, produced by a soil bacterium of the genus Burkholderia sp.: determination of a preferred tautomer and antioxidant activity

• Dandan Li,
• Naoya Oku,
• Yukiko Shinozaki,
• Yoichi Kurokawa and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1489–1494, doi:10.3762/bjoc.16.124

• ; HRESITOFMS (m/z): [M + Na]+ calcd for C10H9NNaO2, 198.0526, found: 198.0525 ; 1H and 13C NMR data are shown in Table 1. Evaluation of Fe3+ binding activity The iron-binding activity was evaluated by the CAS assay developed by Schwyn and Neilands [45]. Compound 1 (2.5 mg) in DMSO (20 μL) was mixed with a blue

• -colored CAS stock solution (50 μL) and further brought up to 100 μL with H2O (final concentration of 1: 160 mM). After 10 min at an ambient temperature, the solution turned orange due to the loss of Fe3+ from the indicator CAS dye, indicating positive to the iron-binding ability of 1. A prolonged reaction

Ferrocenyl-substituted tetrahydrothiophenes via formal [3 + 2]-cycloaddition reactions of ferrocenyl thioketones with donor–acceptor cyclopropanes

• Grzegorz Mlostoń,
• Mateusz Kowalczyk,
• André U. Augustin,
• Peter G. Jones and
• Daniel B. Werz

Beilstein J. Org. Chem. 2020, 16, 1288–1295, doi:10.3762/bjoc.16.109

• of crude mixtures by a short-column chromatography was necessary to remove traces of iron particles formed as a side product after partial decomposition of ferrocenyl containing substrates and/or products formed under reaction conditions. Dimethyl 2-ferrocenyl-2,5-diphenyltetrahydrothiophene-3,3

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

• either remain in the solvent or were removed by the gas stream resulting in the desired porous carbon spheres (Figure 1) [95]. Suslick and co-workers used the USP process for the preparation of well-dispersed iron impregnated porous carbon microspheres. An iron source (FeCl3 or Fe(NO3)3 is already added

• to the precursor solution consisting of sucrose as carbon source and NaCl or NaNO3 as inorganic salt. The pyrolysis of the precursor solution leads to dehydration of carbon as well as iron salt conversion to crystalline or non-crystalline iron species depending on the production conditions. The

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

• . Among other tasks, copper enzymes are known to be actively involved in electron transfer as exemplified by blue copper enzymes, which have captured the interest of chemists and biochemists. Copper can also cooperate with iron to perform activation of O2 and nitrogen oxides (NOx) in cytochrome c oxidases

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

• Clément Ghiazza and
• Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

• acid chlorides (Scheme 6) [23]. Therein, the key was the addition of a catalytic amount of iron powder as the Lewis acid to foster C–Cl bond cleavage and to access the desired products with high yields. The reaction encompassed a broad range of functional groups, including acetate, halides, and

Synthesis and herbicidal activities of aryloxyacetic acid derivatives as HPPD inhibitors

• Man-Man Wang,
• Hao Huang,
• Lei Shu,
• Jian-Min Liu,
• Jian-Qiu Zhang,
• Yi-Le Yan and
• Da-Yong Zhang

Beilstein J. Org. Chem. 2020, 16, 233–247, doi:10.3762/bjoc.16.25

• [10][19][32][33][34]. The results show that two main interactions exist between I12 and the AtHPPD active site (Figure 4), as was observed for mesotrione; the 1,3-dicarbonyl unit is chelated to the iron ion, and the aromatic ring moiety formed π–π interactions with Phe403 and Phe360. Electron