α,γ-Dioxygenated amides via tandem Brook rearrangement/radical oxygenation reactions and their application to syntheses of γ-lactams

• Mikhail K. Klychnikov,
• Radek Pohl,
• Ivana Císařová and
• Ullrich Jahn

Beilstein J. Org. Chem. 2021, 17, 688–704, doi:10.3762/bjoc.17.58

• Derivatizations of lactams 12 lead to valuable compound classes for further elaboration. The alkoxyamine functionality of lactam trans-12b was reductively cleaved by excess zinc in the presence of acetic acid at elevated temperature (Scheme 6); the dihydroxy lactam 14 was obtained in 82% yield. In the presence 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

• catalyst replacements for zinc acetate in the glycolysis of PET are examples of this direction [129][130]. Recent studies focused on molecular complexes as homogeneous catalysts, whereas heterogeneous systems based on solid-supported metal nanoparticles (NPs) have been scarcely investigated. 3.1

• depolymerisation of PET was achieved using zinc acetate as catalyst in hot compressed water [195]. A TPA yield of 90.5% was obtained at 240 °C after 30 min reaction time, using a ZnAc2/PET weight ratio as low as 0.015. For this, a mechanism was speculated in which proton ions act as activators. Methanolysis. To

• ) and 1 wt % Zn(OAc)2 loading (Table 2, entry 1) [201]. The system resulted in partial selectivity to BHET due to the formation of significant amounts of oligomers, mainly BHET dimers, which increased upon standing. The kinetic of the zinc acetate-promoted process was studied over a range of reaction

Amino- and polyaminophthalazin-1(2H)-ones: synthesis, coordination properties, and biological activity

• Zbigniew Malinowski,
• Emilia Fornal,
• Agata Sumara,
• Renata Kontek,
• Karol Bukowski,
• Beata Pasternak,
• Dariusz Sroczyński,
• Joachim Kusz,
• Magdalena Małecka and
• Monika Nowak

Beilstein J. Org. Chem. 2021, 17, 558–568, doi:10.3762/bjoc.17.50

• anticancer drug vatalanib [26][27][28] (Figure 1). On the other hand, aminophthalazinones can be prospective candidates as N- and O-donor ligands to form complexes with biological significant metal ions, such as copper or zinc [29]. Recently, we have demonstrated a strategy for the synthesis of phthalazinone

Synthesis of (Z)-3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones using an Eschenmoser coupling reaction

• Lukáš Marek,
• Lukáš Kolman,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2021, 17, 527–539, doi:10.3762/bjoc.17.47

• occurs to give 3-methoxy-2-oxoindolin-3-yl acetate. Other reducing agents recommended in the literature for the reduction of unprotected isatin (sodium dithionite, zinc, phosphinic acid, etc.) also failed or caused an acetyl group removal. Therefore, we abandoned this strategy. Configuration of products

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• and cis isomers of 2-hydroxy-2-oxo-3-[(phenoxyacetyl)amino]-1,2-oxaphosphorinane-6-carboxylic acid (16, Figure 3) were prepared and evaluated as inhibitors of the zinc-containing β-lactamase II from B. cereus. However, neither stereoisomer had any significant activity [6]. The phosphonodepsidipeptide

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

• of fluorinated cyclopropanes was described by Atkinson in 1952 [9], followed by Tarrant [10], and Misani [11]. Tarrant, Lovelace and Lilyquist synthesized 1,1-difluoro-2,3-dimethylcyclopropane (2) by a reductive debromination using zinc metal (Scheme 1) [10]. After 1960 further methods of generating

• dibromodifluoromethane is a suitable source of difluorocarbene. However, the same reagent produces low yields in the reactions with electron-deficient alkenes. Dolbier et al. reported the cyclopropanation of α-methylstyrene (7) using dibromodifluoromethane and zinc dust in the presence of iodine (Scheme 3) [18]. The

• -dimethoxyethane (Scheme 20) [60]. The difluorocarbene then added to cyclohexene (49) to form difluoronorcarane 50 with good yield. Under similar conditions tetramethylethylene afforded 1,1-difluorotetramethylcyclopropane (4). Trifluoromethyl derivatives of cadmium, bismuth, zinc, and gold: Bis(trifluoromethyl

Total synthesis of decarboxyaltenusin

• Lucas Warmuth,
• Aaron Weiß,
• Marco Reinhardt,
• Anna Meschkov,
• Ute Schepers and
• Joachim Podlech

Beilstein J. Org. Chem. 2021, 17, 224–228, doi:10.3762/bjoc.17.22

• inhibitory activity against three tyrosine kinases (EGFR, VEGFR-1, and c-Met) [5]. As mentioned, it is accessible through the reduction of dehydroaltenusin with zinc powder in acetic acid with intermediate formation of altenusin [1]. Nevertheless, this route cannot be considered as a viable approach to this

Novel library synthesis of 3,4-disubstituted pyridin-2(1H)-ones via cleavage of pyridine-2-oxy-7-azabenzotriazole ethers under ionic hydrogenation conditions at room temperature

• Romain Pierre,
• Anne Brethon,
• Sylvain A. Jacques,
• Aurélie Blond,
• Sandrine Chambon,
• Sandrine Talano,
• Catherine Raffin,
• Branislav Musicki,
• Claire Bouix-Peter,
• Loic Tomas,
• Gilles Ouvry,
• Rémy Morgentin,
• Laurent F. Hennequin and
• Craig S. Harris

Beilstein J. Org. Chem. 2021, 17, 156–165, doi:10.3762/bjoc.17.16

• degradation with the dominant impurity coming from cleavage of the amide bond (Table 3, entry 2) and dissolving metal reduction conditions using zinc were quickly excluded as just 30% conversion was achieved with the added work-up complications (Table 3, entry 3). Finally and rather fortuitously, we turned

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

• + and crown ether, leading to the formation of cyclobutane in a high yield. D’Souza et al. constructed a photosynthetic triad 4 to mimic the photosynthetic reaction center [19]. A BODIPY, an ammonium-functionalized fullerene, and a zinc porphyrin functioned as the energy donor, electron acceptor, and

• BODIPY and the zinc porphyrin. The excited zinc porphyrin further transferred the electron to the fullerene, yielding a charge-separated state, with a long lifetime of 23 µs, indicating the charge stabilization of the supramolecular assembly. Thus, an artificial photocatalytic system that can mimic the

• quantum yield of 3.8 × 10−2 and 0.4, respectively. In contrast, for flavins without the zinc(II)–cyclen unit, only small amounts of product were observed, and the quantum yield was 30 times lower compared to that of the assembly with the flavin chromophore possessing a binding site. The mechanism may be

Synthesis of aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers through the base-mediated reaction between phenols and halothane

• Yukiko Karuo,
• Ayaka Kametani,
• Atsushi Tarui,
• Kazuyuki Sato,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2021, 17, 89–96, doi:10.3762/bjoc.17.9

• the further application of compound 2o in a cyclization reaction. Upon the treatment of 2o with zinc and chlorotrimethylsilane (TMSCl), the intramolecular 1,4-addition reaction of 2o proceeded to give the 2,2-gem-difluorochromane 3 in low yield (Scheme 3). Next, we moved on consideration of the

• C8H6BrClF2O, 269.9259, 271.9238; found, 269.9264, 271.9233. 4-Benzoylmethyl-3-chloro-2,2-difluorochromane (3): To a solution of 2o (210.8 mg, 0.53 mmol) in THF (2.6 mL) was added zinc (42.1 mg, 0.64 mmol) and chlorotrimethylsilane (133 μL, 1.05 mmol) at 0 °C. After stirring for 40 min, the reaction mixture

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

• Dimas J. P. Lima,
• Antonio E. G. Santana,
• Michael A. Birkett and
• Ricardo S. Porto

Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4

• corresponding ammonium salt (±)-106 in 73% yield. The N–O bridge of ammonium salt (±)-106 was reduced with zinc. The resulting diastereomerically pure amino alcohol (±)-107 was then oxidized in the presence of Dess–Martin periodinane to deliver N-methyleuphococcinine ((±)-3). Although Kurtis' synthesis was

Synthesis of tetrafluorinated piperidines from nitrones via a visible-light-promoted annelation reaction

• Vyacheslav I. Supranovich,
• Igor A. Dmitriev and
• Alexander D. Dilman

Beilstein J. Org. Chem. 2020, 16, 3104–3108, doi:10.3762/bjoc.16.260

• iodine by treatment with zinc, followed by the reaction with iodine monochloride. The iodide 2b reacted quite rapidly with the nitrone but the expected fluoroalkylation product was not observed. Instead, the tetrafluorinated piperidine 3a was obtained in a moderate yield (Table 1, entry 2). Apparently

Using multiple self-sorting for switching functions in discrete multicomponent systems

• Amit Ghosh and
• Michael Schmittel

Beilstein J. Org. Chem. 2020, 16, 2831–2853, doi:10.3762/bjoc.16.233

• self-sorting protocols. The present mini review will provide an overview over the latest advancements in this field with a focus on reversibly switchable functions in discrete supramolecular systems. Keywords: copper; fluorescence; self-assembly; self-sorting; zinc porphyrin; Introduction Since self

• )] (Figure 4e). Equally, Schalley and Nitschke developed a guest-induced self-sorting based on two new Zn4L6 cages (Figure 5a) using the aldehyde 9 and the diamine subcomponents 7 and 8 that contained either the naphthalene diimide or zinc porphyrin moiety [51]. Both cages respond selectively to distinct

• reversibility was achieved by the addition of the rhodium porphyrin 19 that reversed the system reviving the state SelfSORT-I. Since both self-sorted states exhibited a distinct fluorescence due to the changes at the zinc porphyrin sites, luminescence was used for the selective detection of DABCO in a mixture

Bifurcated synthesis of methylene-lactone- and methylene-lactam-fused spirolactams via electrophilic amide allylation of γ-phenylthio-functionalized γ-lactams

• Tetsuya Sengoku,
• Koki Makino,
• Ayumi Iijima,
• Toshiyasu Inuzuka and
• Hidemi Yoda

Beilstein J. Org. Chem. 2020, 16, 2769–2775, doi:10.3762/bjoc.16.227

• methylene-lactams (C) through zinc-catalyzed addition to N-carbonyl imides [13][14][16]. Meanwhile, we also developed an umpolung electrophilic allylation of 3-heterosubstituted oxindole D for the synthesis of lactam analog of A (Scheme 1c) [17]. The oxindole D readily reacted with 2-(acetoxy)methyl

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• /bjoc.16.219 Abstract Gold nanoparticles covered with a mixture of ligands of which one type contains solubilizing triethylene glycol residues and the other peripheral zinc(II)–dipicolylamine (DPA) complexes allowed the optical detection of hydrogenphosphate, diphosphate, and triphosphate anions in

• immobilized zinc(II)–dipicolylamine groups increased. A nanoparticle containing a 9:1 ratio of the solubilizing and the anion-binding ligand showed a color change at diphosphate and triphosphate concentrations as low as 10 μmol/L, for example, and precipitated at slightly higher concentrations

• . Hydrogenphosphate induced a nanoparticle precipitation only at a concentration of ca. 400 μmol/L, at which the precipitates formed in the presence of diphosphates and triphosphates redissolved. A nanoparticle containing fewer binding sites was more sensitive, while increasing the relative number of zinc(II

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

Synthesis of 6,13-difluoropentacene

• Matthias W. Tripp and
• Ulrich Koert

Beilstein J. Org. Chem. 2020, 16, 2136–2140, doi:10.3762/bjoc.16.181

• –Crafts acylation is then performed in polyphosphoric acid at 140 °C, giving anthraquinone 11 in 53% yield over two steps. Reduction of 11 to the anthracene 9 proceeded smoothly using zinc powder in 1,4-dioxane and aqueous ammonia under copper catalysis [15]. To achieve good yields, it was crucial to

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• silyl ether-protected 2-hydroxypropanals 15a and 15b via literature procedures [10], followed by the application of the Still–Gennari Z-selective Horner–Wadsworth–Emmons olefination [11]. Koide’s group [12][13] reported that the asymmetric addition of the enyne 16 to acetaldehyde in the presence of zinc

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

• Jundi Xue,
• Ziyi Han,
• Gen Li,
• Khalisha A. Emmanuel,
• Cynthia L. McManus,
• Qiang Sui,
• Dongmian Ge,
• Qi Gao and
• Li Cai

Beilstein J. Org. Chem. 2020, 16, 1955–1962, doi:10.3762/bjoc.16.162

• prepared from the common building block 15 through multiple protecting group manipulations (Scheme 2). The N-Troc group in 15 was removed by treatment with zinc in a mixture of acetic acid and CH2Cl2. The resulting amine 16 was protected immediately as fluorenylmethylenoxy (Fmoc) carbamate by reaction with

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

• -bonding interactions, the narrow π–π stacking provides a sufficient π orbital overlap to produce semiconductor-type electronic band structures and an efficient interplanar charge transport similar to g-C3N4 [192]. Duan and co-workers reported the synthesis of a zinc PDI assembly as a heterogeneous

Disposable cartridge concept for the on-demand synthesis of turbo Grignards, Knochel–Hauser amides, and magnesium alkoxides

• Mateo Berton,
• Kevin Sheehan,
• Andrea Adamo and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2020, 16, 1343–1356, doi:10.3762/bjoc.16.115

• combined with a solution-phase reagent, including: (1) copper(I) oxide to produce N-heterocyclic carbene–Cu(I) complexes for use as catalysts [13]; (2) proline to perform proline-based catalytic reactions [14]; (3) zinc powder to produce organozinc halides in tandem with Negishi couplings [15]; (4) zinc

• advantages allow a more straightforward production and use of these critical reagents. The preparation of organozinc species using zinc packed-bed columns [15][33][34][35] provides examples for the progression toward the on-demand synthesis of other organometallic reagents. While the concept of a reactive

• construction, pressure tolerance, heat conduction, and diameter/particle size matching; (3) the column orientation and setup–filters, etc.; (4) activation of the solid phase. The activation issue is one of the most important factors when considering the metal packing. Although our team had success with zinc

Synthesis of 3-substituted isoxazolidin-4-ols using hydroboration–oxidation reactions of 4,5-unsubstituted 2,3-dihydroisoxazoles

• Lívia Dikošová,
• Júlia Laceková,
• Ondrej Záborský and
• Róbert Fischer

Beilstein J. Org. Chem. 2020, 16, 1313–1319, doi:10.3762/bjoc.16.112

• identified as a readily oxidizable polar component by permanganate detection even at room temperature. The prior attempts to cleave the Troc group by zinc dust in acetic acid [42] failed due to the reduction of the N–O bond. Conclusion In summary, we have developed a new synthetic approach towards 3

Synthesis, antiinflammatory activity, and molecular docking studies of bisphosphonic esters as potential MMP-8 and MMP-9 inhibitors

• Abimelek Cortes-Pacheco,
• María Adelina Jiménez-Arellanes,
• Francisco José Palacios-Can,
• José Antonio Valcarcel-Gamiño,
• Rodrigo Said Razo-Hernández,
• María del Carmen Juárez-Vázquez,
• Adolfo López-Torres and
• Oscar Abelardo Ramírez-Marroquín

Beilstein J. Org. Chem. 2020, 16, 1277–1287, doi:10.3762/bjoc.16.108

• are well known. For example, the coordination of the P=O oxygen atom in bisphosphonates with a zinc cation in the catalytic site of the MMPs has been characterized, both through X-ray diffraction and molecular docking studies [11][36][37]. Consequently, we propose MMP-8 and MMP-9 as potential

• expected, 4–6 could bind the Zn2+ ion in a monodentate fashion through the oxygen atom double bonded to the phosphorus atom (P=O) of one of the phosphonate moieties, as reported in the literature for other structures [38][39]. Only for 3, zinc chelation was observed through the oxygen atom double bonded to

• the carbon atom (C=O) of the ester group (Figure 3). In all cases, a distorted tetrahedral coordination geometry was observed for the zinc ion, caused by the chelation with His197, Glu198, and His207 residues. His201 was far apart from the catalytic site, and the basic nitrogen atom in this residue

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

• zinc chloride at the same temperature [30]. Chemical activation Chemical activation is a one-step method. Impregnation or mixing of the carbon precursor with the activating agent and subsequent carbonization of that mixture leads to highly porous activated carbon materials [8][92]. The activation

Synthesis and properties of quinazoline-based versatile exciplex-forming compounds

• Rasa Keruckiene,
• Simona Vekteryte,
• Ervinas Urbonas,
• Matas Guzauskas,
• Eigirdas Skuodis,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 1142–1153, doi:10.3762/bjoc.16.101

• procedure reported in literature [27]. OLED fabrication and characterization was carried out according to the procedure reported earlier [28]. Materials 2-Aminobenzophenone, 3,5-difluorobenzaldehyde, ammonium acetate, phenothiazine, sodium hydride, sodium sulfate, tert-butyl chloride, zinc chloride