Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• established that the studied iminoxyl radicals reversibly dimerized in the solution. For sterically unhindered dialkyliminoxyl radicals, the radical–dimer equilibrium was quickly reached, shifted toward the dimer, while a first-order decay kinetics of was observed for the iminoxyl radical. For sterically

• hindered tert-butylmethyliminoxyl and diisopropyliminoxyl radicals, as well as for diaryl and alkylaryliminoxyl radicals, the radical–dimer equilibrium was reached slowly, it was shifted toward the free radical, and a second-order decay kinetics was observed. The first synthesized long-lived iminoxyl

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

• determination of adsorbed gas [117]. As a result, physisorption isotherms are obtained by plotting the amount of adsorbed gas na in mol g−1 against the equilibrium relative pressure (p/p0). The resulting isotherms can be grouped in six different types. Type 1 isotherms are concave to the p/p0 axis and na

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

• with the Gaussian software [26]. Firstly, the equilibrium conformer search at the ground state was performed by using the MMFF (molecular mechanics force fields) method, and this geometry was used for further optimization. The vertical singlet and triplet energy values were calculated by using the

• based on m-MTDATA:1:PO-T2T recorded at different voltages (c). EQE, current and power efficiencies of OLED and equilibrium energy diagram for the light-emitting layer m-MTDATA:1:PO-T2T (d, inset). Current density and brightness versus voltages for the device and photoelectron emission spectrum of the

Copper-based fluorinated reagents for the synthesis of CF₂R-containing molecules (R ≠ F)

• Louise Ruyet and
• Tatiana Besset

Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92

• substrates. Based on 19F NMR studies, the authors suggested the following mechanism: first the in situ generation of a CuCF2H complex from TMSCF2H in equilibrium with the corresponding cuprate (Cu(CF2H)2−) occurred followed by the reaction with terminal alkynes under basic conditions. The resulting

Aryl-substituted acridanes as hosts for TADF-based OLEDs

• Naveen Masimukku,
• Dalius Gudeika,
• Oleksandr Bezvikonnyi,
• Ihor Syvorotka,
• Rasa Keruckiene,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 989–1000, doi:10.3762/bjoc.16.88

• structures and equilibrium energy diagrams of the devices are presented in Figure 6a. The values of ionization potentials and electron affinities of solid samples of compounds 3, 4, and 6 were taken as HOMO and LUMO levels as the first approximation (Figure 4b, Table 2). In the devices, MoO3 and LiF were

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

• in equilibrium with a spectator bis-nitrene species 19 and proceeded through styrene 20 insertion, followed by ring closure and release of the aziridine. Interestingly, this otherwise classical mechanism is enabled by the accessibility of doublet and quadruplet states close in energy and this

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• –54, respectively, establishing an equilibrium between the dormant species and the active radicals, which was required for a controlled radical polymerization. No polymerization product was detected in the absence of the benzaldehyde derivatives 52–54, respectively, as well as when the polymerization

Preparation of 2-phospholene oxides by the isomerization of 3-phospholene oxides

• Péter Bagi,
• Réka Herbay,
• Nikolett Péczka,
• Zoltán Mucsi,
• István Timári and
• György Keglevich

Beilstein J. Org. Chem. 2020, 16, 818–832, doi:10.3762/bjoc.16.75

• variety of bases suggested that the base-mediated isomerization leads to a thermodynamic equilibrium between phospholene oxides 1 and 4 catalyzed by the base (see Supporting Information File 1 for the results). In order to test this hypothesis, the two model compounds (1a and 1h) were refluxed with Cs2CO3

• (Table 3). These experiments suggested that the base-mediated isomerization leads to an equilibrium, which is in accordance with other reports in the literature [42]. Thus, this base-mediated isomerization was not studied further with other 3-phospholene oxide derivatives 1. Isomerization of 3

• ), one may predict a well-balanced equilibrium between the 2- or 3-phospholene oxides 4 or 1 in a final state. The experimental results obtained under basic or thermal conditions support this equilibrium concept. In contrast, nearly complete isomerization was observed via the formation of

Efficient synthesis of piperazinyl amides of 18β-glycyrrhetinic acid

• Dong Cai,
• ZhiHua Zhang,
• Yufan Meng,
• KaiLi Zhu,
• LiYi Chen,
• ChangXiang Yu,
• ChangWei Yu,
• ZiYi Fu,
• DianShen Yang and
• YiXia Gong

Beilstein J. Org. Chem. 2020, 16, 798–808, doi:10.3762/bjoc.16.73

• agent [12]. Piperazinyl amide fragments have the ability to form several hydrogen bonds, modulate the acid–base equilibrium constant and change the octanol–water partition coefficient [13]. They are considered as the basic motif for designing many biologically active molecules [14][15]. Some piperazinyl

Synthesis of C₇₀-fragment buckybowls bearing alkoxy substituents

• Yumi Yakiyama,
• Shota Hishikawa and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

• equilibrium between the Pd(IV) intermediates through C–H bond activation. Keywords: buckybowl; C70; rearrangement through C–H bond activation; Introduction The study of buckybowls, the bowl-shaped π-conjugated aromatic hydrocarbons corresponding to the fragments of fullerenes, pioneered by the works on

• above results strongly suggested the existence of an equilibrium between the intermediates corresponding to products 5b and 5c. A possible mechanism is shown in Scheme 2 [21][22][23][24][25]. After the oxidative addition of 4b to Pd0 to generate intermediate A, the neutral palladium(II) intermediate B

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• and deactivated by reaction with Cu(II) resulting in formation of dormant species and Cu(I). Altogether, these reactions must be seen as equilibrium coexisting together. Researchers also spent much time to develop photo-ATRP procedures working without any metal catalyst; that is the photoinduced metal

Oligomeric ricinoleic acid preparation promoted by an efficient and recoverable Brønsted acidic ionic liquid

• Fei You,
• Xing He,
• Song Gao,
• Hong-Ru Li and
• Liang-Nian He

Beilstein J. Org. Chem. 2020, 16, 351–361, doi:10.3762/bjoc.16.34

• vacuum degree is another factor to affect the intermolecular esterification as different vacuum degree can result in a different water removal rate, which may lead to a different equilibrium toward estolides product. Five different levels of vacuum degrees were applied to the reaction system, the results

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

• , this species is in an equilibrium with the −SeCF3 anion. As proposed by Hor and Weng, Deng and Xiao also suggested that CuSeCF3 was the active species in the mechanism. In 2016, the group of Rueping described a sequential copper-catalyzed selenocyanation of aryldiazonium salts, followed by

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

• favor of 4cB. The resulting calculated equilibrium constant of 2.042, corresponding to a 67.1/32.9 ratio of the rotamers (4cB/4cA), was in good agreement with the experimentally by 1H NMR (CDCl3) observed ratio of 65/35. Significantly, the single crystal of 4c, which afforded the crystal structure shown

Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

• Afef Mabrouki,
• Malek Fouzai,
• Armand Soldera,
• Abdelkader Kriaa and
• Ahmed Hedhli

Beilstein J. Org. Chem. 2020, 16, 149–158, doi:10.3762/bjoc.16.17

• intermediate 3 (Scheme 1). Table 1 shows the yields and melting points of the synthesized compounds 2 and 4. The tautomeric equilibrium of compound 3 is illustrated in Scheme 2. On the basis of FTIR data, it has been concluded that in solution, the equilibrium is shifted to the thione form 3a rather than the

• molecular dipole moments. Orange, fluorocarbon compounds; blue, hydrocarbon compounds; green (horizontal line), dipole moment (µ0) of RC. Synthesis of oxadiazole derivatives 2 and 4. Tautomeric equilibrium of compound 3. Obtained oxadiazole derivatives 2 and 4. DSC thermograms data of compounds 2 and 4

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

• Sarah Kölsch,
• Heiko Ihmels,
• Jochen Mattay,
• Norbert Sewald and
• Brian O. Patrick

Beilstein J. Org. Chem. 2020, 16, 111–124, doi:10.3762/bjoc.16.13

• to DNA only with one of the components of the photochromic equilibrium. Moreover, these ligand–DNA interactions can be photochemically switched between the binding and nonbinding form. Interestingly, the photochromic systems applied in this context are almost exclusively photoinduced

• electrocyclization or E-to-Z isomerization reactions, whereas the well-established photochromic cycloaddition–cycloreversion equilibrium to establish photoswitchable DNA binders has so far been widely neglected. In fact, there is only one reported example for the use of the reversible photoinduced dimerization of

• photoswitchable DNA binders based on the photocycloaddition–photocycloreversion equilibrium. In fact, some selected styrylquinolizinium derivatives have already been shown to bind to DNA [61][62][63][64][65][66][67], however, their photocycloaddition reaction and the propensity of the corresponding photodimers to

The interaction between cucurbit[8]uril and baicalein and the effect on baicalein properties

• Xiaodong Zhang,
• Jun Xie,
• Zhiling Xu,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 71–77, doi:10.3762/bjoc.16.9

• % (BALE) and 8.02% (BALE–Q[8]), respectively in artificial intestinal juice. In addition, the release and degradation tended to reach an equilibrium (Figure 10). The release rates of the BALE–Q[8] complex was slower than that of BALE in artificial intestinal juice, but it was faster than the BALE in

Photocontrolled DNA minor groove interactions of imidazole/pyrrole polyamides

• Sabrina Müller,
• Jannik Paulus,
• Jochen Mattay,
• Heiko Ihmels,
• Veronica I. Dodero and
• Norbert Sewald

Beilstein J. Org. Chem. 2020, 16, 60–70, doi:10.3762/bjoc.16.8

• corresponding signals. A representative series of spectra is presented in Figure 1 for polyamide P1. In the thermal equilibrium, approximately 6% of the Z-isomer was present (Figure 1A). Upon irradiation at 350 nm, this fraction steadily increased and reached a level of 65% after 50 min irradiation (Figure 1B

• temperature, and even after 18 days, 13% of the Z-isomer were still present. The thermal equilibrium (5% Z-configuration) was reached only after 40 days in the dark (data not shown). In a previous study, the same azobenzene species incorporated in a hairpin peptide reached a photostationary state of 85% Z

• powerful strategy to obtain photoswitchable Im/Py hairpin polyamides capable of interaction with the dsDNA minor groove only in the Z-configuration. Section of the 1H NMR (600 MHz) spectrum of polyamide P1. A) Initial thermal equilibrium. B) After irradiation at 350 nm for 10 min. C) After irradiation at

Synthesis and characterization of bis(4-amino-2-bromo-6-methoxy)azobenzene derivatives

• David Martínez-López,
• Amirhossein Babalhavaeji,
• Diego Sampedro and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2019, 15, 3000–3008, doi:10.3762/bjoc.15.296

• experiments. Estimates of the percentage of cis/trans isomers in PSSs Based on NMR spectra, we assumed that the fraction of Z-isomer present at equilibrium in the dark was negligible. Since UV–vis spectra obtained during thermal reversion exhibited an isosbestic point, we assumed that only E- and Z-isomers

A green, economical synthesis of β-ketonitriles and trifunctionalized building blocks from esters and lactones

• Daniel P. Pienaar,
• Kamogelo R. Butsi,
• Amanda L. Rousseau and
• Dean Brady

Beilstein J. Org. Chem. 2019, 15, 2930–2935, doi:10.3762/bjoc.15.287

• be the uncyclized β-ketonitrile 7 (see Supporting Information File 1). This suggests that, in solution, the keto–hemiketal equilibrium for the butyrolactone product does not favor completely hemiketal 6, as was observed for the 6-membered cycle 5. The authors therefore propose that formation of the 6

One-pot synthesis of substituted pyrrolo[3,4-b]pyridine-4,5-diones based on the reaction of N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamide with amines

• Valeriya G. Melekhina,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Vitaly S. Mityanov,
• Artem N. Fakhrutdinov,
• Arkady A. Dudinov,
• Vasily A. Migulin,
• Yulia V. Nelyubina,
• Elizaveta K. Melnikova and
• Michail M. Krayushkin

Beilstein J. Org. Chem. 2019, 15, 2840–2846, doi:10.3762/bjoc.15.277

• equilibrium of pyrrolo[3,4-b]pyridin-5-one derivatives 1 in solution. Screening and optimization of the reaction conditions for the synthesis of 7a.a Synthesis of dihydropyrrolone derivatives 7.a Optimization of the reaction conditions towards pyrrolo[3,4-b]pyridin-5-one derivative 1a from 7a. One-pot method

Acid-catalyzed rearrangements in arenes: interconversions in the quaterphenyl series

• Sarah L. Skraba-Joiner,
• Carter J. Holt and
• Richard P. Johnson

Beilstein J. Org. Chem. 2019, 15, 2655–2663, doi:10.3762/bjoc.15.258

• microwave reactor for 30–60 min, with product formation assessed by high field NMR analysis. Under these reaction conditions, m,p'-quaterphenyl is the equilibrium product. This isomer is unchanged by the reaction conditions and all other quaterphenyl isomers rearrange to m,p' as the dominant or sole product

• facile acid-catalyzed interconversion, as well as the fact that m-terphenyl (2) is favored at equilibrium (observed ratio 1:2:3 is <1:69:31) and used theory to explain this product selectivity [25]. This preference is consistent with formation of the most stable arenium ion intermediate, as shown by DFT

• favoring the 2,2'-isomer 9 (97%) at equilibrium [26]. Aryl shifts occur readily in naphthalene, with beta-substitution favored at equilibrium. Skeletal rearrangements of fused arene rings are also possible and can proceed through several mechanisms. The first example was reported by Dansi and Salvioni in

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

• (known as log Pow), which is defined as the equilibrium concentration ratio of the analyte distributed between these two phases [52]. The theoretical logarithm of the partition coefficient for the water/n-octanol mixture at both constant temperature and pressure was computed using Equation 1 [53

Synthetic terpenoids in the world of fragrances: Iso E Super^® is the showcase

• Alexey Stepanyuk and
• Andreas Kirschning

Beilstein J. Org. Chem. 2019, 15, 2590–2602, doi:10.3762/bjoc.15.252

• . investigated the influence of Brønstedt and Lewis acids on the formation of Georgywood® (35). It was found that Lewis acids such as AlCl3 shift the equilibrium towards Georgywood® (35) type products especially when employed in over-stoichiometric amounts. Using different Brønstedt acids, the ratios between the

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

• mixtures of monomeric and dimeric ring-closed products at high dilution (4.5 mM), which means the energy gap between these compounds has become significantly smaller. The equilibria that are established within a metathesis reaction depend on the equilibrium rate constants, in this case between the