Polarity effects in 4-fluoro- and 4-(trifluoromethyl)prolines

• Vladimir Kubyshkin

Beilstein J. Org. Chem. 2020, 16, 1837–1852, doi:10.3762/bjoc.16.151

• this weakens their interaction. Similar considerations can be applied to the acidity of the carboxylic group (Figure 6B), where the mutual orientation of the C–X dipole and the carboxylate -CO2− charge has an effect [74]. In diastereomeric fluoroprolines there is a large difference in the mutual

One-pot synthesis of oxazolidinones and five-membered cyclic carbonates from epoxides and chlorosulfonyl isocyanate: theoretical evidence for an asynchronous concerted pathway

• Esra Demir,
• Ozlem Sari,
• Yasin Çetinkaya,
• Ufuk Atmaca,
• Safiye Sağ Erdem and
• Murat Çelik

Beilstein J. Org. Chem. 2020, 16, 1805–1819, doi:10.3762/bjoc.16.148

• oxazolidinones and five-membered cyclic carbonates of various structures. The most well-known strategies for the synthesis of oxazolidinones are the reaction of an amino alcohol with phosgene [5][22], the carbonylation reaction of β-amino alcohols with CO2 or dialkyl carbonates [23][24][25][26][27], the

• multicomponent reaction of rare-earth metal amides [28], the reaction of CO2 with propargylamines or aziridines [29][30] and the cycloaddition reaction of epoxides with isocyanates [31][32]. On the other hand, for the synthesis of five-membered cyclic carbonates, the cycloaddition of CO2 to epoxides, the

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• , mild oxidizing additives such as amine oxides, aminophosphines, phosphine oxides, and sulfoxides may be used as promoters to facilitate the dissociation step, by oxidatively removing one of the CO ligands in form of CO2 [40]. The most common oxidants are N-morpholine N-oxide (NMO), trimethylamine N

• -workers [46]. In this study, a wide variety of 1,6-enynes bearing fluorine atoms or fluorine-containing groups at the alkenyl or alkynyl positions were synthesized and evaluated as substrates in the intramolecular PKR with dicobalt octacarbonyl [Co2(CO)8] in CH2Cl2 and promoted by NMO. In general, the

• to high yields, except for those bearing marked electron withdrawing groups (Scheme 7). In 2005, Billard and co-workers reported the PKR of α-trifluoromethylated homoallylamine derivatives (Scheme 8) [47]. Both 1,7-enynes 18a and 18b (n = 1) underwent PKR in the presence of 1 equiv of Co2(CO)8 and 10

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

• synthetically controlled to improve the photocatalytic CO2 reduction performance by Zhang and co-workers using plasma treatment [87]. The general process of photocatalysis in metal oxide semiconductors is illustrated in Figure 4 and is as follows: the photoexcitation of an electron across the band gap generates

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

• methods from coal precursors. Yang et al. synthesized nitrogen-doped activated carbon from petroleum coke for an enhanced CO2 capture [7]. Pietrzak et al. used high volatile bituminous coals, brown coals and anthracites for modified activated carbon preparation [5][10][11][12]. Lillo-Ródenas et al

• solutions Xu et al. used energy-rich carbon precursors for the spherical carbon preparation via ultrasonic spray pyrolysis. Lithium, sodium or potassium propiolates are one class of such energy rich materials and exhibit leaving groups such as CO, CO2 or C2H2 eliminated by decarbonylation or decarboxylation

• . After preparation of char by carbonization of the precursor materials for a certain time at a defined temperature under inert gas atmosphere, steam, air or CO2 activate the materials at higher temperatures (800–1000 °C) to form a porous structure according to the Equations 1–3 [81][85][86]. It is

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• difficult to be directly activated by the excited state photocatalyst. For these reasons, the photocatalyzed decarboxylation often proceeds on the corresponding carboxylates, which are easier to be oxidized. This photoinduced SET, followed by the loss of CO2 as the sole byproduct, gives access to the

• reducible moiety, such as a redox-active ester (RAE). These species can accept one electron from the photocatalyst, and the ensuing reduced species releases the corresponding C(sp3) radical after a fragmentation and CO2 loss. This approach represents an alternative to oxidative decarboxylations, allowing

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• also can be applied to the reduction of carbon dioxide (CO2). Many photocatalytic materials containing porphyrins have been developed for CO2 reactions in organic synthesis, including photoinduced transformations [52][53][54][55]. Nagaraja and co-workers reported the first porphyrin-based MOF for

• different epoxides, whose conversion was proportional to the substrate size, using MOF1 and tetra-n-butylammonium bromide (TBAB) as photocatalyst and co-catalyst, respectively (Scheme 25). A successful gram-scale protocol was developed opening up perspectives for using these materials in CO2 reuse

• . This work is crucial for the success of the subsequent industrial process introduced by the pharmaceutical company Sanofi [80]. After this seminal publication, a consortium between Sanofi and UK/China universities also reported a green protocol for artemisinin synthesis using supercritical CO2 as a

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates

• Phil M. Pithan,
• Sören Steup and
• Heiko Ihmels

Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82

• , within the series of representative alkali and earth alkali ions (Li+, Na+, K+, Mg2+, Ca2+) and transition metal cations (Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Hg2+, Pb2+), only the addition of Cu2+ caused a significant coloration of the initially colorless solution of 3a (c = 20 µM) in MeCN (Figure 1

• . Absorption (A) and fluorescence spectrum (B) of 3a in MeCN (c = 5 µM) in the absence (black) and in the presence of metal ions ca. 1 h after the addition. Red: Cu2+ (c = 15 µM), orange: Hg2+ (c = 100 µM), blue: Li+, Na+, K+, Mg2+, Ca2+, Mn2+, Fe2+, Co2+, Ni2+, Zn2+, Ag+, and Pb2+ (c = 100 µM each); λex = 470

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• give excellent chemical yields with good enantioselectivities for products 57–59 (Scheme 14). Interestingly, this approach could be extended to the synthesis of amino acids using cesium fluoride in the presence of CO2 gas to afford 60 and 61. From the representative examples shown below, it appears

• developed by Suginome [125], or B2pin2, along with various N-hydroxylamine derivatives (400) under ligand-influenced Cu catalysis, high regioselectivities were typically obtained [126]. A year later, Popp et al. reported a Cu-catalyzed regiospecific boracarboxylation of vinyl arenes using 1 atm CO2 and

KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

• Qiao Lin,
• Shiling Zhang and
• Bin Li

Beilstein J. Org. Chem. 2020, 16, 492–501, doi:10.3762/bjoc.16.44

• TMSN3 as the azide source [10] (Scheme 1a). Coates described a Co2(CO)8-catalyzed ring-opening hydroformylation of oxazolines for the synthesis of β-amidoaldehydes [11] (Scheme 1a). However, the ring-opening N-alkylation of 2-oxazolines to produce 2-aminoethyl acetate derivatives under basic conditions

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• reaction conditions. The authors suggested first the photoexcitation of a [Cu(I)] species. Then, the excited [Cu(I)]* species reduces the NHP ester to form a carboxyl radical and the phthalimide anion, which binds to the [Cu(II)] species. After the elimination of CO2, the recombination of the alkyl radical

Two antibacterial and PPARα/γ-agonistic unsaturated keto fatty acids from a coral-associated actinomycete of the genus Micrococcus

• Amit Raj Sharma,
• Enjuro Harunari,
• Naoya Oku,
• Nobuyasu Matsuura,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 297–304, doi:10.3762/bjoc.16.29

• the cells at a final density of 5 × 103 cells/well, and 200 µL cultures thus made were incubated for 96 h at 37 °C in an atmosphere of 5% CO2 in air with 100% humidity. The viability of the cells was visualized by the addition of 50 μL of the medium containing XTT (1 mg/mL) and PMS (40 µg/mL) to each

• , and the plates were cultured for an additional 24 h at 37 °C in a 5% CO2 incubator. The luciferase activity and secreted alkaline phosphatase SEAP activity were measured in each well by using a Steady-Glo® luciferase assay (Promega, Madison, WI, USA) and Great ESCAPe SEAP Reporter System3 (Clontech

Combination of multicomponent KA² and Pauson–Khand reactions: short synthesis of spirocyclic pyrrolocyclopentenones

• Riccardo Innocenti,
• Elena Lenci,
• Gloria Menchi and
• Andrea Trabocchi

Beilstein J. Org. Chem. 2020, 16, 200–211, doi:10.3762/bjoc.16.23

• slightly lower yield. Attempts to carry out the Pauson–Khand reaction directly on the amino group before the acylation step did not work, nor using a modified approach using ammonium chloride and 1.5 equivalents of Co2(CO)8 under an inert atmosphere, as reported for similar reactions in the presence of

• Pauson–Khand (C) reaction. In a dry round bottom flask under a nitrogen flow Co2(CO)8 (0.1 equiv), N,N,N’,N’-tetramethylthiourea (0.6 equiv) and a solution of the enyne compound (1 equiv) were successively added in dry toluene (20 mL/mmol). Then, the reaction mixture was kept under a CO atmosphere and

Extension of the 5-alkynyluridine side chain via C–C-bond formation in modified organometallic nucleosides using the Nicholas reaction

• Renata Kaczmarek,
• Dariusz Korczyński,
• James R. Green and
• Roman Dembinski

Beilstein J. Org. Chem. 2020, 16, 1–8, doi:10.3762/bjoc.16.1

• of alkynyl nucleosides 2 and 3 were confirmed by 1H and 13C NMR spectroscopy and high-resolution mass spectrometry [64][65]. The conversion of alkynyl nucleosides 2 and 3 into the corresponding dicobalt hexacarbonyl nucleosides complexes of 4 and 5 was accomplished at room temperature (Co2(CO)8, THF

• reappearance upfield in the reaction products (i.e., 3.17 ppm in 6a and 4.27 ppm in 6b). In the 13C NMR spectra, the slightly broadened resonance of the metal carbonyl carbons at 199–200 ppm (199.4 ppm in both 6a and 6b) were characteristic of the product alkyne–Co2(CO)6 complexes. In the IR spectra, the

• the synthesis of hexacarbonyl dicobalt 5-alkynyluridines (4 or 5): A round-bottom flask was charged under a nitrogen atmosphere with Co2(CO)8 (0.222 g, 0.650 mmol), alkynyl nucleoside 2 or 3 (0.500 mmol), and THF (10 mL). The mixture was stirred at room temperature (22 °C) for 1 h. The solvent was

Palladium-catalyzed Sonogashira coupling reactions in γ-valerolactone-based ionic liquids

• László Orha,
• József M. Tukacs,
• László Kollár and
• László T. Mika

Beilstein J. Org. Chem. 2019, 15, 2907–2913, doi:10.3762/bjoc.15.284

• into Class 2, of which applications should be strictly limited, particularly in pharmaceutical industry. To develop an environmentally benign alternative of this useful method, the reaction has been extended to green solvents such as water [16], fluorous solvents [17], supercritical CO2 [18], and very

Carbazole-functionalized hyper-cross-linked polymers for CO₂ uptake based on Friedel–Crafts polymerization on 9-phenylcarbazole

• Dandan Fang,
• Xiaodong Li,
• Meishuai Zou,
• Xiaoyan Guo and
• Aijuan Zhang

Beilstein J. Org. Chem. 2019, 15, 2856–2863, doi:10.3762/bjoc.15.279

• a high surface area and a high total pore volume. The BET specific surface areas of P3 was up to 769 m2 g−1 with narrow pore size distribution and the CO2 adsorption capacity of P11 was up to 52.4 cm3 g−1 (273 K/1.00 bar). Keywords: 9-phenylcarbazole; CO2 uptake; Friedel–Crafts polymerization

• to monomer, the reaction temperature T1, the amount of used catalyst and the concentration of reactants. Additionally, the CO2 uptake of the obtained polymers was explored. Results and Discussion The synthesis of HCPs is shown in Scheme 1 and Table 1. Using the Friedel–Crafts reaction, 11 samples (P1

• the concentration of reactants slightly, a great increase of the pore volume can be accomplished without sacrificing the BET special surface area. CO2 uptake behavior The presence of many CO2-philic sites (N-bearing substituents) and narrow pore distribution in the networks could improve the molecular

Preparation of anthracene-based tetraperimidine hexafluorophosphate and selective recognition of chromium(III) ions

• Qing-Xiang Liu,
• Feng Yang,
• Zhi-Xiang Zhao,
• Shao-Cong Yu and
• Yue Ding

Beilstein J. Org. Chem. 2019, 15, 2847–2855, doi:10.3762/bjoc.15.278

• temperature. In its free form, three emission bands at 402, 423, and 447 nm were observed at c = 5.0⋅10−6 M, which were ascribed to the emission of anthracene (Figure 2). When adding 30 equiv of K+, Na+, Li+, Ag+, NH4+, Zn2+, Cd2+, Ca2+, Ni2+, Pb2+, Cu2+, Co2+, Al3+, Hg+, Hg2+, Rh3+, Ir3+, Cr2+, Ga3+, Ru3

• +, Na+, Li+, Ag+, NH4+, Zn2+, Cd2+, Ca2+, Ni2+, Pb2+, Cu2+, Co2+, Al3+, Hg+, Hg2+, Rh3+, Ir3+, Cr2+, Ga3+, Ru3+, and Fe3+, respectively. The emission intensities of the resulting mixtures were similar to that of a solution containing only 3 and Cr3+. These experimental results show that 3 can capture

• )–N(1): 1.310(5) Å; and C(3)–N(2): 1.315(5) Å. Fluorescence spectra of 3 (c = 5.0⋅10−6 M) upon addition of 30 equiv of salts of K+, Na+, Li+, Ag+, NH4+, Zn2+, Cd2+, Ca2+, Ni2+, Pb2+, Cu2+, Co2+, Al3+, Cr3+, Hg+, Hg2+, Rh3+, Ir3+, Cr2+, Ga3+, Ru3+, and Fe3+, respectively (c = 1.5⋅10−4 M) in CH3CN/DMSO

Chemical tuning of photoswitchable azobenzenes: a photopharmacological case study using nicotinic transmission

• Lorenzo Sansalone,
• Jun Zhao,
• Matthew T. Richers and
• Graham C. R. Ellis-Davies

Beilstein J. Org. Chem. 2019, 15, 2812–2821, doi:10.3762/bjoc.15.274

• KCl, 1.25 NaH2PO4, 7 MgCl2, 0.5 CaCl2, 26 NaHCO3, 10 glucose, 100 sucrose, 3 sodium pyruvate, 1.3 sodium ascorbate equilibrated with 95% O2/5% CO2 (pH 7.3–7.4). The brain slices were then incubated for 15 min at 33 °C in artificial cerebrospinal fluid (ACSF, mM: 125 NaCl, 2.5 KCl, 1.25 NaH2PO4, 1

• MgCl2, 2 CaCl2, 26 NaHCO3, 10 glucose, 3 sodium pyruvate, 1.3 sodium ascorbate; 95% O2/5% CO2, pH 7.3–7.4) and held at room temperature. Brain slices were then transferred to the recording chamber of a BX-61 microscope (Olympus, PennValley, PA, USA) and superfused with ACSF at room temperature. Medial

Diversity-oriented synthesis of spirothiazolidinediones and their biological evaluation

• Sambasivarao Kotha,
• Gaddamedi Sreevani,
• Lilya U. Dzhemileva,
• Milyausha M. Yunusbaeva,
• Usein M. Dzhemilev and
• Vladimir A. D’yakonov

Beilstein J. Org. Chem. 2019, 15, 2774–2781, doi:10.3762/bjoc.15.269

• under a 5% CO2 atmosphere. Cells were maintained in RPMI 1640 (Jurkat, K562, U937) (Gibco) supplemented with 4 mM glutamine, 10% FBS (Sigma) and 100 units/mL penicillin streptomycin (Sigma). All types of cells were grown in an atmosphere of 5% CO2 at 37 °C. The cells were subcultured at 2–3 days

• dormancy) of drug candidates and toxic compounds. In vitro cytotoxicity was assessed using a standard MTT colorimetric assay in a similar manner as described in [60][61]. HEK293 cells were plated in 96-well microassay culture plates (1 × 104 cells per well) and grown overnight at 37 °C in a 5% CO2

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• installation of an oxygen atom on one face, promoting the addition of CO2 from the other face, resulting in enantioenriched carboxylated product 29 after acidification (Scheme 10). The authors described similar results involving the asymmetric electrocarboxylation of other prochiral aromatic ketones in a

• and regenerate the Cu–L* catalyst (Scheme 30). In 2014, Wang and Lu reported a method for asymmetric fixation of CO2 via electrocarboxylation of 82 catalyzed by an electrogenerated chiral [CoI(salen)]− complex [68]. The potentiostatic electrolysis of 82 in an undivided cell in presence of catalytic

• chiral Co(II)-(R,R)salen complex 83 in DMF saturated with CO2 resulted in the formation of 84 in a low yield but with good enantioselectivity (Scheme 31). Very recently, Meggers research group described an application of an asymmetric Lewis acid catalyst using electricity to provide a synthetic route

Plasma membrane imaging with a fluorescent benzothiadiazole derivative

• Pedro H. P. R. Carvalho,
• Jose R. Correa,
• Karen L. R. Paiva,
• Daniel F. S. Machado,
• Jackson D. Scholten and
• Brenno A. D. Neto

Beilstein J. Org. Chem. 2019, 15, 2644–2654, doi:10.3762/bjoc.15.257

• umbilical vein endothelial cells, HUVEC. The cells were maintained according to ATCC (American type culture collection) recommendations at 37 °C in an atmosphere containing 5% CO2. Cell viability. For cell viability the synthesized compound BTD-4APTEG was tested at two different concentrations, 10 and 100

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

• Celine Bittner Dirk Bockfeld Matthias Tamm Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38102 Braunschweig, Germany 10.3762/bjoc.15.246 Abstract Novel alkyne-bridged ferrocenophanes [fc{CO2(CH2)nC≡}2] (2a: n = 2; 2b: n = 3) were synthesized

• from the corresponding terminal diacetylenic ferrocenes [fc{CO2(CH2)nC≡CH}2] (1a: n = 2; 1b: n = 3) through ring-closing alkyne metathesis (RCAM) utilizing the highly effective molybdenum catalyst [MesC≡Mo{OC(CF3)2CH3}3] (MoF6; Mes = 2,4,6-trimethylphenyl). The metathesis reaction occurs in short time

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

• Cu(II) complex 6, along with reduced Ir(II) photocatalyst 7. The resulting carboxyl radical extrudes CO2 and sequentially recombines to generate Cu(III) species 9. At this stage, SET from 7 to 9 closes the photoredox catalytic cycle and produces an alkylcopper(II) species 10. Under the addition of

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

• Christoph W. Grathwol,
• Nathalie Wössner,
• Sören Swyter,
• Adam C. Smith,
• Enrico Tapavicza,
• Robert K. Hofstetter,
• Anja Bodtke,
• Manfred Jung and
• Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

• -30ADSF for liquid CO2 and two LC-20ADXR for modifier and make-up delivery), an on-line supercritical fluid extraction module (SFE-30A auto extractor equipped with 0.2 mL extraction vessels) for reaction monitoring, an autosampler (SIL-30AC) for purified compounds, a column thermostat (CTO-20AC) equipped

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• nanoreactor because there is an acceleration of the dimerization by two orders of magnitude and the turnover of the catalyst was demonstrated. The synthesis of cyclic carbonates from epoxides and CO2 is an efficient method for CO2 fixation. The development of an effective chiral catalyst for the efficient

• kinetic resolution of epoxides with CO2 remains a big challenge. Recently, Ema and co-workers described a chiral binaphthyl strapped Zn(II) porphyrin with triazolium halide units as a bifunctional catalyst for the kinetic resolution of epoxides with CO2 [63]. The condensation of click-reaction-derived