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

• ) spectra of neat films, and dilute THF and toluene solutions of the studied derivatives are presented in Figure 3a. The derivatives 3, 4, and 6 exhibited intense acridan-related lowest energy bands (LEB) of absorption at ≈340 nm, affected by the type of substituents. The LEB of the solutions and films of 5

• stabilizes the twist conformers stimulating the formation of intermolecular CT states. Consequently, in the PL spectra of neat films of the derivatives the emission band assigned to CT is more prominent. The PL quantum yields of neat films of compound 3, 4, 5, and 6 were found to be 0.03, 0.08, 0.32 and 0.08

• [29]. DSC curves of compounds 4 and 5. Absorption and PL spectra (λex = 330 nm) of compounds 3–6. a) Absorption spectra as neat films, dilute THF and toluene solutions. b) PL and phosphorescence spectra in dilute THF solutions at 77 K. a) Cyclic voltammogram of derivative 3 in dichloromethane (a three

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

• trifluoroacetic acid, a mixture containing the corresponding 2- and 3-phospholene oxides (4a and 1a) in a ratio of 11:89 was obtained. However, when phospholene oxide 1a was heated in neat methanesulfonic acid at 160 °C for 24 h, 4a and 1a in a ratio of 97:3 were obtained, but the yield of the mixture was 57% due

• toluene, DMF, or DMSO. However, the maximal content of phenyl-2-phospholene oxide 4a in the crude product was only 4%. In contrast, when neat 3-phospholene oxide 1a was heated to 200 °C without any solvent, the ratio of the 2- and 3-phospholene oxide 4a and 1a increased to 71:29 in the crude product after

• °C in neat, and the progression of the reactions was followed by gas chromatography for two days using biphenyl as internal standard. According to repeated experiments, the errors in measured relative concentrations were below 5%. The concentration curves undoubtedly refer to an equilibrium reaction

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• Hz); IR (neat)/cm−1) ν̃: 2921 (w), 2851 (w), 1560 (m), 1535 (m), 1412 (m), 1386 (s), 1257 (s), 1154 (m), 1103 (s), 1070 (s), 982 (m), 912 (m), 750 (s), 739 (m), 638 (m), 580 (w); UV–vis (CHCl3): λmax [nm] (log ε): 367 (5.57), 506 (5.97); HRMS–MALDI (m/z): [M]+ calcd for C54H32N4F4B2, 834.2749; found

• , 126.2, 123.2, 121.6, 96.8, 88.9, 54.639.2, 35.8, 31.9, 30.4, 22.7, 14.0; UV–vis (CHCl3) λmax [nm] (log ε): 434 (6.06), 564 (4.28), 610 (4.20); IR (neat)/cm−1) ν̃: 2921 (m), 2851 (m), 1451 (m), 1305 (m), 1211 (m), 1072 (m), 1008 (s), 939 (m), 787 (s), 750 (s), 708 (s), 639 (s); HRMS–MALDI (m/z): [M

• , 94.4, 89.9, 54.4, 53.9, 39.1, 35.8, 32.1, 30.5, 29.8, 22.9, 19.0, 14.3, 11.7 ppm; IR (neat)/cm−1) ν̃: 2921 (m), 2851 (m), 1451 (m), 1305 (m), 1211 (m), 1072 (m), 1008 (s), 939 (m), 787 (s), 750 (s), 708 (s), 639 (s); UV–vis (CHCl3) λmax [nm] (log ε): 430 (5.84), 563 (4.30), 608 (4.35); HRMS–MALDI (m/z

Aerobic synthesis of N-sulfonylamidines mediated by N-heterocyclic carbene copper(I) catalysts

• Faïma Lazreg,
• Marie Vasseur,
• Alexandra M. Z. Slawin and
• Catherine S. J. Cazin

Beilstein J. Org. Chem. 2020, 16, 482–491, doi:10.3762/bjoc.16.43

• for C50H66BCuF4N6: C, 66.62; H, 7.38; N, 9.32; found: C, 66.55; H, 7.46; N, 9.47. General catalytic procedure. A vial was charged with [Cu(Triaz)2]BF4 (4.5 mg, 1 mol %), the alkyne (0.5 mmol), the azide (0.6 mmol) and the amine (0.6 mmol). The reaction was stirred neat for the appropriate amount of

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

• following the reported method [48] employing copper catalysis, and tested on our starting material upon variation of copper salts, solvents and temperature, resulting in the neat reaction under CuI catalysis being optimal when carried out for 2 h at 100 °C under microwave irradiation (see Supporting

Microwave-assisted synthesis of 2-substituted 4,5,6,7-tetrahydro-1,3-thiazepines from 4-aminobutanol

• María C. Mollo,
• Natalia B. Kilimciler,
• Juan A. Bisceglia and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2020, 16, 32–38, doi:10.3762/bjoc.16.5

• necessary precursors were prepared by the sequence depicted in Table 1. Regarding the cyclodehydration reaction, in the same experimental conditions than before (neat PPSE, 1–8 min, 90 °C), thioamidoalcohols 3i–k afforded the corresponding tetrahydro-1,3-thiazepines 4i–k in good to high yields as the only

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

• , 149.4, 137.2, 115.6, 114.6, 103.6, 85.7, 82.4, 81.8, 74.0, 63.7, 37.9, 35.6, 33.8, 20.9, 20.6; IR (neat, ATR) 3197, 3077, 2967, 2089, 2049, 2017, 1747, 1714, 1691, 1587 cm−1; ESI+–MS (m/z): [M]+ calcd for C25H22Co2N2O13, 698.9684; found, 698.9689. Hexacarbonyl dicobalt 3',5'-di-O-acetyl-2'-deoxy-5-[3

• ); 13C NMR (125 MHz, CDCl3) δ 199.4, 170.3, 160.3, 160.1, 158.9, 149.6, 136.2, 115.1, 108.7, 104.1, 90.0, 85.7, 82.3, 81.1, 74.1, 63.8, 55.3, 54.7, 37.7, 26.5, 20.9, 20.6; IR (neat, ATR) 3200, 2997, 2962, 2088, 2048, 2018, 1746, 1711, 1664, 1598 cm−1; ESI+–MS (m/z): [M]+ calcd for C31H28Co2N2O16

• , 81.8, 74.0, 63.7, 40.2, 37.8, 28.9, 20.9, 20.6; IR (neat, ATR) 3208, 2956, 2926, 2089, 2050, 2018, 1746, 1715, 1688, 1597 cm−1; ESI+–MS (m/z): [M + Na]+ calcd for C30H25Co2N2NaO14, 776.9789; found, 776.9788. Hexacarbonyl dicobalt 2',3',5'-tri-O-acetyl-5-(hex-5-en-1-yn-1-yl)uridine (7a). To a solution

SnCl₄-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives

• Kesatebrhan Haile Asressu and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2019, 15, 2990–2999, doi:10.3762/bjoc.15.295

• as catalyst under neat conditions, which provided the expected β-ring-opened product 12 in a moderate yield (Table 1, entry 5). This acetolysis reaction resulted in regioselective acetylation of positions O-7 and O-2 in line with the principles of green chemistry. It is known that anomeric acetates

A new approach to silicon rhodamines by Suzuki–Miyaura coupling – scope and limitations

• Thines Kanagasundaram,
• Antje Timmermann,
• Carsten S. Kramer and
• Klaus Kopka

Beilstein J. Org. Chem. 2019, 15, 2569–2576, doi:10.3762/bjoc.15.250

• starting material 12 could be significantly reduced when acetonitrile was exchanged with dichloromethane in the triflation reaction to provide triflate 21 neat and more reliable. Screening of different boron species and catalysts showed that, like in the syntheses of O, S, Se, and Te-rhodamines, boroxines

α,ß-Didehydrosuberoylanilide hydroxamic acid (DDSAHA) as precursor and possible analogue of the anticancer drug SAHA

• Shital K. Chattopadhyay,
• Subhankar Ghosh,
• Sarita Sarkar and
• Kakali Bhadra

Beilstein J. Org. Chem. 2019, 15, 2524–2533, doi:10.3762/bjoc.15.245

• viscous liquid [45]. IR (neat): 3267, 3076, 1666, 1579 cm−1; 1HNMR (400 MHz, CDCl3) δ 8.33 (brs, 1H), 7.56 (d, J = 8 Hz, 2H), 7.29 (t, J = 7.6 Hz, 2H), 7.10 (t, J = 7.6 Hz, 1H), 5.84–5.74 (m, 1H), 5.03–4.95 (m, 2H), 2.36 (t, J = 7.6 Hz, 2H), 2.06 (q, J = 6.8 Hz, 2H), 1.72 (quin, J = 7.2 Hz, 2H), 1.44

• cool to room temperature and then concentrated in vacuo. The residual mass was purified by column chromatography on silica gel (CHCl3/MeOH 98:2) to provide the coupled product 10a (101 mg, 77%) as colourless solid. Mp 148–150 °C; IR (neat): 3296, 3211, 2926, 2858, 1663, 1639 cm−1; 1H NMR (400 MHz, DMSO

• Celite, the filter cake was washed with methanol (5 mL) and the combined filtrate was concentrated in vacuo. The residue was purified by column chromatography on silica gel (CHCl3/MeOH 9:1) to provide SAHA (34 mg, 91%) as colorless solid. Mp 158–159 °C; IR (neat): 3267, 2927, 2854, 1667, 1645 cm–1; 1H

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• particularly thermally unstable, with dimerization occurring at temperatures higher than −75 °C [4]. The dimerization of triafulvene derivatives is hypothesised to occur via a [4 + 4] cycloaddition pathway (Scheme 7) [4]. Whilst the dimers are also unstable (rapid decomposition when neat), they can be observed

Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkyl-substituted benzimidazoles with arenes in the superacid CF₃SO₃H. NMR and DFT studies of dicationic electrophilic species

• Dmitry S. Ryabukhin,
• Alexey N. Turdakov,
• Natalia S. Soldatova,
• Mikhail O. Kompanets,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1962–1973, doi:10.3762/bjoc.15.191

• of 1 and give rise to the corresponding 2-diarylmethylbenzimidazoles 9a–l. The best results were obtained in neat TfOH, which gave high yields of reaction products (54–86%) at room temperature after 2–3 h. Other acids were not so efficient. Thus, reactions under the action of sulfuric acid H2SO4 or

• . Then, we studied reactions of 2-hydroxyalkylbenzimidazoles 3a–c, 4, 7, and 8. It was found that these reactions needed extremely harsh reaction conditions, heating in neat TfOH at 140 °C in glass high pressure tubes (Table 4, Scheme 2). Only at this high temperature the formation of Friedel–Crafts

Vicinal difunctionalization of alkenes by four-component radical cascade reaction of xanthogenates, alkenes, CO, and sulfonyl oxime ethers

• Shuhei Sumino,
• Takahide Fukuyama,
• Mika Sasano,
• Ilhyong Ryu,
• Antoine Jacquet,
• Frédéric Robert and
• Yannick Landais

Beilstein J. Org. Chem. 2019, 15, 1822–1828, doi:10.3762/bjoc.15.176

• was then filtered and concentrated in vacuo to give a residue, which was subjected to silica gel column chromatography using hexane/EtOAc 10:1 as eluent, affording 5a (52.9 mg, 0.15 mmol, 38%). Ethyl (E)-4-(2-((benzyloxy)imino)acetyl)decanoate (5a): IR (neat, ZnSe) νmax (cm−1): 3065, 2955, 1732, 1584

• , 31.6, 29.2, 27.1, 26.4, 22.6, 14.2, 14.1; EIMS m/z (relative intensity): 316 (4), 227 (8), 199 (2), 91 (100); HRMS–EI (m/z): [M − C2H5O]+ calcd for C19H26NO3, 316.1913; found, 316.1916. Phenyl (E)-4-(2-((benzyloxy)imino)acetyl)decanoate (5b): IR (neat, ZnSe) νmax (cm−1): 2954, 2928, 1760, 1685, 1196

• -((benzyloxy)imino)-4-cyclohexyl-5-oxohexanoate (5c): IR (neat, ZnSe) νmax (cm−1): 3065, 2978, 1681, 1497, 1370, 1251, 1210; 1H NMR (CDCl3, 500 MHz) δ 7,48 (s, 1H), 7.38–7.33 (m, 5H), 5.25 (s, 2H), 4.12–4.06 (m, 2H), 3.27–3.23 (m, 1H), 2.22–2.17 (m, 1H), 2,13–2.06 (m, 1H), 1.96–1.92 (m, 1H), 1.86–1.85 (m, 1H

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

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

Formation of an unexpected 3,3-diphenyl-3H-indazole through a facile intramolecular [2 + 3] cycloaddition of the diazo intermediate

• Andrew T. King,
• Hugh G. Hiscocks,
• Lidia Matesic,
• Mohan Bhadbhade,
• Roger Bishop and
• Alison T. Ung

Beilstein J. Org. Chem. 2019, 15, 1347–1354, doi:10.3762/bjoc.15.134

• product was crystallised from dichloromethane to give a brown crystalline solid (0.064 g, 0.137 mmol, 27%); mp 183–184 °C; IR (neat) vmax/cm−1: 3057, 3025, 2959, 2926, 2650, 2322, 2112, 1943, 1591, 1490, 1470, 1445, 1349, 1263, 1205, 1127, 1023, 843, 748, 607; 1H NMR (500 MHz, CDCl3) δ 7.28–7.31 (m, H-Ar

Efficient resolution of racemic crown-shaped cyclotriveratrylene derivatives and isolation and characterization of the intermediate saddle isomer

• Sven Götz,
• Andreas Schneider and
• Arne Lützen

Beilstein J. Org. Chem. 2019, 15, 1339–1346, doi:10.3762/bjoc.15.133

• corresponds to the saddle conformer and is marked with 1-S. a) 1H NMR spectrum of the neat crown isomers of (rac)-1 in CD3OD (400 MHz, 298 K); b) 1H NMR spectrum in CD3OD (400 MHz, 298 K) of a sample of (rac)-1 after heating it to 200 °C in DMSO and quenching the solution by pouring it into an ice water

Understanding the unexpected effect of frequency on the kinetics of a covalent reaction under ball-milling conditions

• Ana M. Belenguer,
• Adam A. L. Michalchuk,
• Giulio I. Lampronti and
• Jeremy K. M. Sanders

Beilstein J. Org. Chem. 2019, 15, 1226–1235, doi:10.3762/bjoc.15.120

• less expensive than traditional solution-based methods, because they require little or no solvent. Moreover, mechanochemical syntheses often give quantitative yields of products [2][3][4]. Manual or mechanical grinding can be performed “neat”, i.e., in the absence of solvent (neat grinding, NG

• Information File 2), which we selected here to fit the experimental curve for 15 Hz ball-mill neat grinding. If a model is built on Scheme 2, with k1, k1' k2, Figure 2A is generated. Remarkably, despite the simplifying assumptions used in this model, the general features of the experimental curve are well

• by its ability to facilitate mass transport. Having ascertained that the model of Equation 4 well describes the non-linear kinetics observed for neat grinding, it is worth considering this model with respect to LAG kinetics. While the non-linearity is not so evident under LAG conditions, the

Mechanochemical amorphization of chitin: impact of apparatus material on performance and contamination

• Thomas Di Nardo and
• Audrey Moores

Beilstein J. Org. Chem. 2019, 15, 1217–1225, doi:10.3762/bjoc.15.119

• demonstrated as potential issue for milling. Milling is considered a neat method, yielding clean products but careful considerations must be taken when selecting milling media for this reason as well. Experimental Chemicals Practical grade chitin was purchased from Sigma-Aldrich Co. LLC (St-Louis, MO). Milling

Ugi reaction-derived prolyl peptide catalysts grafted on the renewable polymer polyfurfuryl alcohol for applications in heterogeneous enamine catalysis

• Alexander F. de la Torre,
• Gabriel S. Scatena,
• Oscar Valdés,
• Daniel G. Rivera and
• Márcio W. Paixão

Beilstein J. Org. Chem. 2019, 15, 1210–1216, doi:10.3762/bjoc.15.118

• attributed to the typical amide vibrations and are not present in neat PFA. In addition, the bands at around 800, 740 and 600 cm−1 confirm the presence of a 2,5-disubstituted furan ring typical of the PFA polymeric matrix [18]. The thermo-oxidative degradation of polymeric catalysts 3 and 4 was also examined

• using TGA, and compared with that of PFA (see Supporting Information File 1). This analysis showed that both polymers 3 and 4 are quite stable up to 100 °C, but as expected, decompose earlier than neat PFA. Thus, as main difference a significant loss of mass is observed for 3 and 4 at the range of 100

• –300 °C, whereas neat PFA is still stable at that temperature. This first degradation can be attributed to the decomposition of the peptidic skeleton, while at around 300 °C the decomposition of the polymeric lattice matrix starts, also of PFA. This analysis further demonstrates the incorporation of

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

• 35 minutes. After the synthesis, the resulting polymers were washed with 200 mL of water and 100 mL of ethanol and dried at 80 °C for 12 hours to yield a beige powder (denoted NG-HCP (neat grinding-HCP)). For more details on the experimental procedure see Supporting Information File 1. After

Precious metal-free molecular machines for solar thermal energy storage

• Meglena I. Kandinska,
• Snejana M. Kitova,
• Vladimira S. Videva,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• Stanislav B. Baluschev,
• Silvia E. Angelova and
• Aleksey A. Vasilev

Beilstein J. Org. Chem. 2019, 15, 1096–1106, doi:10.3762/bjoc.15.106

• defined their photophysical behavior in neat acetonitrile (ACN) solution and in the presence of barium cations. Figure 1 shows the absorption spectra of dyes 4a–d measured at different concentrations (cM) of Ba(ClO4)2. All dye solutions have similar absorption profiles with a broad long wavelength band in

• that in neat CD3CN (Supporting Information File 1, Figure S9 and Figure S10). A common behavior demonstrated in Figure 2 was observed: the fluorescence quantum yield of all dyes (Table 1) decreases if the concentration of the Ba2+ ions increases, i.e., the formation of the trans-dye–Ba2+ complexes

Fabrication, characterization and adsorption properties of cucurbit[7]uril-functionalized polycaprolactone electrospun nanofibrous membranes

• Changzhong Chen,
• Fengbo Liu,
• Xiongzhi Zhang,
• Zhiyong Zhao and
• Simin Liu

Beilstein J. Org. Chem. 2019, 15, 992–999, doi:10.3762/bjoc.15.97

• ratio of PCL/CB[7] is 100:200), which is far higher than the CDs content in CD-functionalized nanofibers [13][14][15] and the calixarene content in the calixarene-functionalized nanofibers [20]. Figure 1 presents the SEM photographs and fiber diameter distributions of neat PCL and the PCL/CB[7

• ] nanofibers with various amounts of CB[7] (the information of compositions, diameter and morphology of electrospun nanofibers are collected in Supporting Information File 1, Table S1). The bead-free neat PCL nanofibers with an average fiber diameter (AFD) of 193 nm were successfully electrospun from the PCL

• solution in formic acid/DMF with lower concentration (8%, w/v, with respect to the total volume of formic acid and DMF). Furthermore, the diameter of about 57% PCL nanofibers is lower than 200 nm. Compared to the electrospun PCL nanofibers in reported literatures [12][15][16][17], the AFD of neat PCL

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

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

• . In 2008, they have established a [2 + 2] photodimerization through solid-state grinding either in neat or liquid-assisted conditions [93]. To achieve 100% stereospecific products they considered resorcinol derivatives as hydrogen-bond donors for the photodimerization of 1,2-di(pyridin-4-yl)ethylene

• has been shown to proceed with excellent turnover numbers. Recently, Friščić and Cinčić with co-workers reported an elaborative study on the halogen bonding between 1,3,5-trifluoro-2,4,6-triiodobenzene and triphenylphosphine, -arsine, and -stibine under neat mechanochemical conditions or through

• organocatalysis using PhI (10 mol %)–mCPBA at ambient conditions as well as under neat mixing [115]. The N1,N1-dibenzylbenzene-1,2-diamine (Figure 27) which is an integrated system by the combination of aniline and N,N-dibenzylaniline led to the successful formation of 1-benzyl-2-phenyl-benzo[d]imidazole 48 under

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• example of “in water” metathesis with a heterogenous catalytic system. Pauly et al. used alginate beads as a matrix to encapsulate the G-II catalyst for the RCM of substrate 31 and 33 (Scheme 7) [44]. Alginate amide beads perform best in neat water as they facilitate the diffusion of hydrophobic

• ammonium tags Classical metathesis catalysts such as G-II and HG-II are among the most active, stable and versatile ruthenium complexes. Despite their high activity and remarkable stability, they are sparingly soluble in neat water, thus challenging their use as homogeneous catalysts in pure water. To

• ][53]. Grubbs and co-workers were the first to introduce water-soluble catalysts which displayed metathesis activity in aqueous media [54]. In 1996, Grubbs et al. reported that complexes 1 and 2 catalyze the living opening polymerization of norbornene derivatives 35 and 36 in neat water. Interestingly