Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• -temperature operation. The sample temperature was calibrated against neat ethylene glycol and neat methanol standards. Selective inversion experiments at subambient temperature effected the selective inversion with iBURP shapes [25]. The spin–lattice relaxation time T1 for each site was determined with

Activation of pentafluoropropane isomers at a nanoscopic aluminum chlorofluoride: hydrodefluorination versus dehydrofluorination

• Maëva-Charlotte Kervarec,
• Thomas Braun,
• Mike Ahrens and
• Erhard Kemnitz

Beilstein J. Org. Chem. 2020, 16, 2623–2635, doi:10.3762/bjoc.16.213

• presence of HSiEt3, either in a solvent (C6D6 or C6D12), or in neat silane under similar conditions (all reactions were carried out at 70 °C and monitored for 7 days). The treatment of 10a and HSiEt3 in C6D12 generated 1 and 10b again, in addition to traces of 1,1,2-trifluoropropene (2, Scheme 4, top). The

• , middle). Compound 10a is transformed into 1, 11, and 12 with the additional presence of traces of the Friedel–Crafts product CF2=CFCH2C6D5 (3). However, in neat silane, 10a was converted into 1, 10b, 2, 1,1,1,2-tetrafluoropropane (13), 1,1-difluoropropene (5), and 1,1,1-trifluoropropane (6, Scheme 4

• reaction patterns and to demonstrate the conceivable transformations between certain products, which were observed in the activation of 10a in the presence of ACF and HSiEt3. It turned out that the tetrafluoropropene 13 reacts in the presence of silane with ACF as the catalyst in C6D12 or neat silane to

Conformational preferences of fluorine-containing agrochemicals and their implications for lipophilicity prediction

• Daniela Rodrigues Silva,
• Joyce K. Daré and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2020, 16, 2469–2476, doi:10.3762/bjoc.16.200

• . Conclusion In summary, the overall molecular polarity is influenced not only by the nature of the substituent group (as considered by additive techniques of prediction), but also by the orientation of the neat molecular dipole moment vector. In this sense, methods that ignore such influences result in

Host–guest interaction of cucurbit[8]uril with oroxin A and its effect on the properties of oroxin A

• Zhishu Zeng,
• Jun Xie,
• Guangyan Luo,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 2332–2337, doi:10.3762/bjoc.16.194

• containing 10% DMSO by volume, OA (500 μmol·L−1) upon the addition of different molar equivalents of Q[8]: (a) 0, ( b ) 0.35, (c) 0.44, (d) 1.03, (e) 1.60 and (f) neat Q[8]. (A) The UV–vis absorption spectra recorded for OA in the presence of Q[8] (c(Q[8]), labeled a–k: 0, 0.2, 0.4, 0.6, ..., 2.0 × 10–5

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

• Patrizia Andreozzi,
• Lorenza Tamberi,
• Elisamaria Tasca,
• Gina Elena Giacomazzo,
• Marta Martinez,
• Mirko Severi,
• Marco Marradi,
• Stefano Cicchi,
• Sergio Moya,
• Giacomo Biagiotti and
• Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

• reactions, and even in nanomaterials preparation [1][2][3][4][5]. Indeed, solid-state mechanochemical methodologies are a viable alternative to traditional syntheses in solution [4] for the preparation of complex molecules, either under solvent-free conditions, named ‘neat grinding’, or in nearly solvent

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

• points reported in the work are uncorrected. Unless stated otherwise, solvents and chemicals were obtained from commercial sources and used without further purification. Infrared spectra were recorded on a Perkin Elmer instrument with neat sample and only major peaks are reported in cm−1. The 1H and 13C

Selective preparation of tetrasubstituted fluoroalkenes by fluorine-directed oxetane ring-opening reactions

• Clément Q. Fontenelle,
• Thibault Thierry,
• Romain Laporte,
• Emmanuel Pfund and
• Thierry Lequeux

Beilstein J. Org. Chem. 2020, 16, 1936–1946, doi:10.3762/bjoc.16.160

• equiv) in dichloromethane. The reaction was slow and required heating (50–65 °C) for 26 h to reach a 75% conversion and afforded a mixture of E/Z-1a in 60% yield. However, a low E/Z selectivity (40:60) was observed (Table 1, entry 1). When using neat benzylic alcohol, completion was achieved after 20 h

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

The McKenna reaction – avoiding side reactions in phosphonate deprotection

• Katarzyna Justyna,
• Joanna Małolepsza,
• Damian Kusy,
• Waldemar Maniukiewicz and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119

• , being especially affected by the type of substituents in the vicinity of the phosphonic group [1]. Usually the reaction is carried out for 1–3 days [26][27], in a solution of DCM or acetonitrile (ACN), although it can also be performed in neat BTMS. As far as the reaction temperature is concerned it can

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

• oxime 1g (Scheme 5). Oxime radical 16 is a pale blue crystalline compound that is stable at room temperature [35][62], whereas liquid neat di-tert-butyliminoxyl radical (8) decomposed within a week [59]. The di(1-adamantyl)iminoxyl radical (16) was characterized by IR, UV–vis, EPR, and NMR spectroscopy

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• ). Both the pH of the medium (specific acid catalysis) and general acid catalysis by the ammonium groups of F-1 were potentially important for the ring opening reactions. The ring openings were conducted in three different media: neat methanol, a mixture of methanol and dichloromethane, and a mixture of

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