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

The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

• Narasimhamurthy Rajeev,
• Toreshettahally R. Swaroop,
• Ahmad I. Alrawashdeh,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Seegehalli M. Anil,
• Kuppalli R. Kiran,
• Chandra,
• Paris E. Georghiou,
• Kanchugarakoppal S. Rangappa and
• Maralinganadoddi P. Sadashiva

Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

• ], iron nanoparticle-catalyzed reactions of 2-naphthol with benzaldehyde and some of its derivatives with thiourea [22], isothiocyanato oxindoles with ketones [23], ammonium isothiocyanates with chalcones [24], and α-isothiocyanato esters with α-keto amides [25]. Among the synthetic methods available for

Starazo triple switches – synthesis of unsymmetrical 1,3,5-tris(arylazo)benzenes

• Andreas H. Heindl and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2020, 16, 22–31, doi:10.3762/bjoc.16.4

• /C-catalyzed reduction by H2 in different solvents, SnCl2, or iron under acidic conditions were not successful either. In all cases, the reactions produced complicated mixtures, and the target compound could neither be identified nor isolated. At this stage, the second strategy via Pd-catalyzed

Bacterial terpene biosynthesis: challenges and opportunities for pathway engineering

• Eric J. N. Helfrich,
• Geng-Min Lin,
• Christopher A. Voigt and
• Jon Clardy

Beilstein J. Org. Chem. 2019, 15, 2889–2906, doi:10.3762/bjoc.15.283

• Information File 1, Table S2). CYPs are heme-dependent iron proteins that catalyze a wide range of reactions [83][84]. The reactions typically involve substrate radical generation by the activated iron species and subsequent hydroxylation. Terpenes are mainly composed of nonactivated hydrocarbons that are

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• ][81]. In some cases, a metal–iron interaction, e.g., as shown in complex IV [79], could be observed depending on the ring size of the ferrocenophane ligand [82][83][84][85]. Furthermore, ferrocenophanes functionalized with bridges containing various heteroatoms were utilized as ion sensors for a wide

• 1b crystallises in the monoclinic space group P21/c. The asymmetric unit for the molecular structure of 1b shows only half a molecule with the other half being generated through an inversion centre located on the iron atom. For both structures, the iron-centroid (Fe–Ct) distances of 1.6947(12) Å (Fe

• ethyne [94]. Interestingly, a disorder of the iron position in the butynylferrocene 1a can be observed, obviously being responsible for the slightly longer Fe–Ct distances as compared to 1b. The main position Fe has an occupation of 74%. The disordered position Fe’ with an occupation of 26% is located

Photochromic diarylethene ligands featuring 2-(imidazol-2-yl)pyridine coordination site and their iron(II) complexes

• Andrey G. Lvov,
• Max Mörtel,
• Anton V. Yadykov,
• Frank W. Heinemann,
• Valerii Z. Shirinian and
• Marat M. Khusniyarov

Beilstein J. Org. Chem. 2019, 15, 2428–2437, doi:10.3762/bjoc.15.235

• cyclohexenone bridges show good cycloreversion quantum yields of 0.20–0.32. The thermal stability of closed-ring isomers reveals half-lives of up to 20 days in solution at room temperature. The ligands were used to explore coordination chemistry with iron(II) targeting photoswitchable spin-crossover complexes

• . Unexpectedly, dinuclear and tetranuclear iron(II) complexes were obtained, which were thoroughly characterized by X-ray crystallography, magnetic measurements, and Mössbauer spectroscopy. The formation of multinuclear complexes is facilitated by two coordination sites of the diarylethene, acting as a bridging

• ligand. The bridging nature of the diarylethene in the complexes prevents photocyclization. Keywords: diarylethene; 2-(imidazol-2-yl)pyridine; iron(II) complex; photochromism; Introduction Transition metal complexes with photoactive ligands are of great interest for advanced photonic applications [1][2

Reversible switching of arylazopyrazole within a metal–organic cage

• Anton I. Hanopolskyi,
• Soumen De,
• Michał J. Białek,
• Yael Diskin-Posner,
• Liat Avram,
• Moran Feller and
• Rafal Klajn

Beilstein J. Org. Chem. 2019, 15, 2398–2407, doi:10.3762/bjoc.15.232

• found to be stabilized in their zwitterionic form when confined to iron oxide nanoparticles [24]. Similarly, the ability of anthracenes to photodimerize greatly depends on the curvature of their “host” nanoparticle [25]. Despite these advances, we are still far from achieving the ease and elegance, with

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• different catalysts, such as palladium, copper, silver, iron, nickel, ruthenium, cobalt, etc. Palladium catalysis Palladium is a member of the nickel triad in the periodic table, and palladium complexes exist in three oxidation states, Pd(0), Pd(II), and Pd(IV). Straightforward interconversion between

• (Scheme 31a) [74]. Che and co-workers [75] achieved a similar α-fluorination of β-ketoesters and N-Boc-oxindoles (Scheme 31b). Compared with Du’s method, Che employed both AgClO4 and chiral iron(III)-salan complexes as the catalyst. In 2016, the group of Nishikata [76] described a copper-catalyzed site

• positions with a nucleophilic fluorine source. Notably, Groves adapted the method for the 18F-radiofluorination of benzylic and aliphatic C–H bonds using no-carrier-added [18F]-fluoride with Mn(salen)OTs [84]. In 2013, Lectka’s group [85][86] reported an iron-catalyzed C(sp3)–H fluorination of benzylic

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

• systems based on zinc with excellent activity has been designed and used. The role of iron in synthetic chemistry Iron being the most abundant heavy element on earth with low biological toxicity along with cost economy and high reactivity was explored by Kharasch and Fields in the 1940s and Tamura and

• Kochi in 1970s in the field of catalysis [64][65]. Iron in the form of its salts, oxides, iron–NHC complexes, iron pincer complexes, ferrocenes and half sandwiched iron complexes found to be the center of attraction in the field of catalytic organic synthesis. Variable oxidation states of iron (–2 to +5

• ) allow it to catalyze a number of organic reactions viz., nucleophilic substitutions, addition reactions, hydrogenations/hydrosilylations, cycloisomerizations, electrophilic aromatic substitutions, cross-coupling reactions, oxidative additions and reductive eliminations [66]. Iron–catalyzed C–H

Enantioselective Diels–Alder reaction of anthracene by chiral tritylium catalysis

• Qichao Zhang,
• Jian Lv and
• Sanzhong Luo

Beilstein J. Org. Chem. 2019, 15, 1304–1312, doi:10.3762/bjoc.15.129

• combination, affording adduct 5a in 91% ee and 70% yield at room temperature (Table 1, entries 17 and 18). In a control experiment, we found that chiral iron salt 2f itself turned out to be ineffective to catalyze the reaction in the absence of trityl chloride (Table 1, entry 19), indicating that the reaction

• used, the reaction showed high yield (93% for 5o) but low enantioselectivity (23% ee, Scheme 3a). Surprisingly, the chiral iron salt 2f itself in the absence of trityl chloride also promoted the reaction, showing a relatively lower activity with 85% yield of 5o but opposite chiral induction (−65% ee

• , Scheme 3a). The electron-rich nature of dimethylanthracene may account for catalysis with the iron salts. On the other hand, an opposite chiral induction in this case is a clear indication of distinctive carbocation catalysis instead of metal Lewis acid catalysis in the presence of trityl chloride. In

Genomics-inspired discovery of massiliachelin, an agrochelin epimer from Massilia sp. NR 4-1

• Jan Diettrich,
• Hirokazu Kage and
• Markus Nett

Beilstein J. Org. Chem. 2019, 15, 1298–1303, doi:10.3762/bjoc.15.128

• -producing bacterium Massilia sp. NR 4-1 and predicted to direct the biosynthesis of a molecule that is structurally related to the thiazoline-containing siderophore micacocidin. In order to track this compound, we analyzed the metabolic profiles of Massilia cultures grown under different iron concentrations

• . A compound which was found to be predominantly produced under iron deficiency was subsequently isolated. Its structural characterization by spectroscopic and bioinformatic analyses revealed a previously not known diastereomer of the cytotoxic alkaloid agrochelin. The structure of this natural

• domain organization of the two corresponding biosynthetic assembly lines further indicated that Massilia sp. NR 4-1 does not produce micacocidin, but a derivative of this secondary metabolite. The isolation of siderophores from microorganisms is usually straightforward due to their iron-dependent

Mechanochemical synthesis of hyper-crosslinked polymers: influences on their pore structure and adsorption behaviour for organic vapors

• Sven Grätz,
• Sebastian Zink,
• Hanna Kraffczyk,
• Marcus Rose and
• Lars Borchardt

Beilstein J. Org. Chem. 2019, 15, 1154–1161, doi:10.3762/bjoc.15.112

• ’-biphenyl) and six equiv of anhydrous iron(III) chloride as mediator into a 45 mL zirconium oxide milling vessel filled with 22 balls (10 mm, 3.19 ± 0.05 g) of the same material (Figure 1). Consequently, the vessel was transferred into a (Pulverisette 7) premium line (Fritsch GmbH) and milled at 500 rpm for

• recent past we have already observed this behaviour for other reactions including iron(III) chloride [42][44], and thus we have proposed several countermeasures which greatly reduce the vessel pressure during such reactions. For this polymerization reaction we decided to add small quantities of liquid to

• procedure HCP was synthesised through a mechanochemical reaction. This was accomplished by transferring 0.821 g 4,4’-bis(chloromethyl)-1,1’-biphenyl (Sigma-Aldrich) and 3.179 g (six equiv) of anhydrous iron(III) chloride (Sigma-Aldrich) as mediator into a 45 mL zirconium oxide milling vessel filled with 22

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• chemistry of that self-assembled Fe(II) cage [4][12][83]. In 2015, Mal’s group successfully reproduced the synthesis of Nitschke’s tetrahedral iron-cage molecule under solvent-free mechano-milling conditions [84]. Subcomponent self-assembly from components A, B, C, D and Fe(II) in a solvent-free environment

Synthesis of acylglycerol derivatives by mechanochemistry

• Karen J. Ardila-Fierro,
• Andrij Pich,
• Marc Spehr,
• José G. Hernández and
• Carsten Bolm

Beilstein J. Org. Chem. 2019, 15, 811–817, doi:10.3762/bjoc.15.78

• catalysts such as iron(III) chloride or bismuth(III) triflate was reported. However, the implementation of these protocols in the ball mill only led to trace amounts (less than 5% yield) of the protected monoacylglycerol 4a. Finally, one of the well-established Jacobsen catalysts for the epoxide ring

Synthesis of polydicyclopentadiene using the Cp₂TiCl₂/Et₂AlCl catalytic system and thin-layer oxidation of the polymer in air

• Zhargolma B. Bazarova,
• Ludmila S. Soroka,
• Alex A. Lyapkov,
• Мekhman S. Yusubov and
• Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

• , those of iron and copper, peroxy and carbonyl group-containing compounds. Unlike the initiation, the steps of chain propagation during polymers oxidation are well studied [28]. The first step of chain propagation consists of the interaction of the free R• radical with oxygen (Scheme 6) and occurs at an

Synthesis and biological investigation of (+)-3-hydroxymethylartemisinin

• Toni Smeilus,
• Farnoush Mousavizadeh,
• Johannes Krieger,
• Xingzhao Tu,
• Marcel Kaiser and
• Athanassios Giannis

Beilstein J. Org. Chem. 2019, 15, 567–570, doi:10.3762/bjoc.15.51

• inactivity against Plasmodium. Furthermore, in cellular systems free ferrous iron [19] as well as haem [20][21] have been proposed to be the main iron sources for artemisinin activation. However, the results on that matter remain controversial [4][22]. Our results challenge the radical hypothesis of