Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands

• Sergey V. Norkov,
• Anton V. Cherkasov,
• Andrey S. Shavyrin,
• Maxim V. Arsenyev,
• Viacheslav A. Kuropatov and
• Vladimir K. Cherkasov

Beilstein J. Org. Chem. 2021, 17, 273–282, doi:10.3762/bjoc.17.26

• was discussed previously [29]. The reaction of 4 with malononitrile-derived gem-dithiolate (5b, Scheme 1, route 2) also proceeded under mild conditions in DMF and bicyclic o-quinone 6b was obtained in a good yield. The brown crystals suitable for X-ray analysis were grown from an acetone/diethyl ether

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

• biotransformation of gem-difluorocyclopropanecarboxamide (±)-83 (Scheme 34) occurred rapidly and under mild conditions to give (1R,3R)-amide 83 (46% yield, >99% ee) and (1S,3S)-acid 82 (51% yield, 87 % ee). Enantioselective hydrogenation of difluorocyclopropenes: Recently, Mikami and co-workers reported the

• . Further applications of free radical chemistry have developed through the use of radical initiators under comparatively mild conditions to form cyclopropylmethyl radicals, which can readily release their strain by opening to give homoallyl radicals. gem-Difluorocyclopropanes, because of their

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

• obtain aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers. The products are structurally unique and represent highly functionalized compounds containing the gem-difluoroalkyl ether unit in addition to a bromochloromethyl group. The reaction proceeds under mild conditions and is compatible with variously

Silver-catalyzed synthesis of β-fluorovinylphosphonates by phosphonofluorination of aromatic alkynes

• Yajing Zhang,
• Qingshan Tian,
• Guozhu Zhang and
• Dayong Zhang

Beilstein J. Org. Chem. 2020, 16, 3086–3092, doi:10.3762/bjoc.16.258

• vinylphosphonates from simple and commercially available alkynes proceeds under mild conditions with high stereoselectivity, and thus enabling the rapid construction of molecular complexity. Results and Discussion We investigated the reaction of phenylacetylene (1a), Selectfluor®, and diethyl phosphite to afford β

• -fluorovinylphosphonates under mild conditions. First, we examined the catalytic activity of various transition metal catalysts, including Au, Ag, Cu, Rh, and Pd complexes (Supporting Information File 1). Among these metal salts, silver salts, especially AgOAc, were the most effective catalysts for generating the desired

Metal-free synthesis of biarenes via photoextrusion in di(tri)aryl phosphates

• Hisham Qrareya,
• Lorenzo Meazza,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 3008–3014, doi:10.3762/bjoc.16.250

• yields but under very mild conditions with no need of any (photo)catalyst or additive, despite the scope of the process is in part limited since the presence of at least one electron-withdrawing group on an aromatic ring completely suppressed the reaction. Emission spectrum of compound 1e (red) and of

Ultrasound-assisted Strecker synthesis of novel 2-(hetero)aryl-2-(arylamino)acetonitrile derivatives

• Emese Gal,
• Luiza Gaina,
• Hermina Petkes,
• Alexandra Pop,
• Castelia Cristea,
• Gabriel Barta,
• Dan Cristian Vodnar and
• Luminiţa Silaghi-Dumitrescu

Beilstein J. Org. Chem. 2020, 16, 2929–2936, doi:10.3762/bjoc.16.242

• of aldimine and ketoimine substrates under mild conditions [18]. Early studies reported a positive effect of sonication on the classical aminocyanation procedures. The reaction rate of the classical Strecker reaction using cyanide salts, amines and aromatic carbonyl derivatives [19] or piperidone [20

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

• were prepared by the reaction of 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane (1) with the corresponding substrates, resulting in the selective alkylation of one of the nitrogen atoms of the imidazole ring. The reaction proceeds under mild conditions in a polar solvent, giving the alkylated

• corresponding to the CH(CF3)2 group were significantly broadened. While all attempts to involve guanine in the reaction with 1 failed (DMSO, 25–70 °C, 4 d), the reaction of adenine (5) or 2-fluoroadenine (6) with tetrakis(trifluoromethyl)-1,3-dithietane (1) was found to proceed under mild conditions (DMSO, 25

Asymmetric Mannich reactions of (S)-N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimines with yne nucleophiles

• Ziyi Li,
• Li Wang,
• Yunqi Huang,
• Haibo Mei,
• Hiroyuki Konno,
• Hiroki Moriwaki,
• Vadim A. Soloshonok and
• Jianlin Han

Beilstein J. Org. Chem. 2020, 16, 2671–2678, doi:10.3762/bjoc.16.217

• , only a slight decrease in the yield was observed (84%) along with the same stereochemical outcome. Also, the chiral sulfinyl auxiliary can be easily removed under acidic conditions to give the free amine. Treating 3i with HCl gas in methanol at 0 °C, the tert-butylsulfinyl group was cleaved under mild

• conditions and the target primary amine 4 was obtained with 57% yield. Conclusion In conclusion, we have explored arylethynes as new nucleophiles for the Mannich reactions of (R)-N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimine. Quite unexpectedly, the diastereoselectivity of the reactions were noticeably

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

• such as hydrodefluorinations and dehydrofluorinations were observed, followed by hydroarylation and Friedel–Crafts-type reactions under mild conditions. Keywords: aluminum fluoride; C–F bond activation; dehydrofluorination; hydrodefluorination; hydrofluorocarbons; Introduction Hydrofluorocarbons

• for the synthesis of hydrofluoroolefins (HFOs), which have been regarded as the next generation of refrigerants, exhibiting zero ozone depletion potential (ODP) and a negligible GWP [11][12][13]. A considerable amount of studies has been carried out to synthesize HFOs under mild conditions [11][14][15

• activation of C–F bonds under mild conditions, and hence the addition of the silane HSiEt3 as a hydrogen source [27][48][49]. More recently, ACF was shown to efficiently convert the fluoroalkenes HFO-1234yf (1) and HFO-1234ze (4a) in the presence of the hydrogen source HSiEt3 into the hydrodefluorination or

Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction

• Tony Jin,
• Malickah Hicks,
• Davis Kurdyla,
• Sabahudin Hrapovic,
• Edmond Lam and
• Audrey Moores

Beilstein J. Org. Chem. 2020, 16, 2477–2483, doi:10.3762/bjoc.16.201

• FTIR and PXRD showed little to no structural change to the biomaterials after metal deposition. Heck coupling results demonstrate the importance of using ChNCs as opposed to ChsNCs in order to control the redox chemistry of Pd, with full product yield in relatively mild conditions using PdNP@ChNC. TEM

Chan–Evans–Lam N1-(het)arylation and N1-alkеnylation of 4-fluoroalkylpyrimidin-2(1H)-ones

• Viktor M. Tkachuk,
• Oleh O. Lukianov,
• Mykhailo V. Vovk,
• Isabelle Gillaizeau and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2020, 16, 2304–2313, doi:10.3762/bjoc.16.191

• required for the coupling are not tolerated with the highly electrophilic ketimine moiety of 4-trifluoromethylpyrimidin-2(1H)-ones. The CEL reaction was successfully applied in the N-arylation of many heterocyclic systems [35][36][37] including non-fluorinated pyrimidin-2(1H)-ones [38][39] under mild

• conditions. There are a few thorough studies on this reaction with pyrimidine and purine nucleoside bases and their derivatives which are most closely related to fluorine-containing substrates 1 [40][41][42]. However, considering the high sensitivity and capricious nature of CEL reaction, we wish to report

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

• . One exciting development in C–F bond formation is the use of small-molecule photosensitizers, allowing the reactions i) to proceed under mild conditions, ii) to be user-friendly, iii) to be cost-effective and iv) to be more amenable to scalability than typical photoredox-catalyzed methods. In this

• for inducing different organic transformations under extremely mild conditions without threatening reagents and conditions [83][84][85]. There are three commonly observed and distinct mechanisms of photocatalytic activation [86] in the context of organic synthesis: i) Most reported photocatalytic

• -light irradiation by a household (19 W) compact fluorescent light (CFL) bulb (emitting variable wavelengths in the range of ≈365–625 nm) [195] and under mild conditions. Control reactions revealed that both the PS and light were essential for the reaction to occur. According to their report, benzylic C

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

• have reported the TMSOTf-catalyzed synthesis of highly substituted imidazoles from α-azidochalcones under mild conditions [65]. As a sequel, the synthesis of oxazoles with an arylimino substituent has been accomplished in this work. The biologically important arylimino group [66][67][68][69] integrated

Reactions of 3-aryl-1-(trifluoromethyl)prop-2-yn-1-iminium salts with 1,3-dienes and styrenes

• Thomas Schneider,
• Michael Keim,
• Bianca Seitz and
• Gerhard Maas

Beilstein J. Org. Chem. 2020, 16, 2064–2072, doi:10.3762/bjoc.16.173

• effect of the iminium activation. The Diels–Alder reaction of alkyne 1a with 2,3-dimethylbutadiene also occurred under very mild conditions and yielded the iminium-substituted 1,4-cyclohexadiene 4-Ch (Scheme 2), which, due to its high sensitivity toward moisture, was not purified but was further

Synthesis of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines

• Ksenia I. Kaskevich,
• Anastasia A. Babushkina,
• Vladislav V. Gurzhiy,
• Dmitrij M. Egorov,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2020, 16, 1947–1954, doi:10.3762/bjoc.16.161

• thiazolo[3,2-a]-5-oxopyrimidines 3a–f in good yields (Scheme 6). Likely, in this case the attack by the N3 atom was more favorable than by the N1 atom due to the steric effect of the substituent in position 6. The reactions proceeded under mild conditions within 3–5 hours. Anhydrous K2CO3 was used as a

Regiodivergent synthesis of functionalized pyrimidines and imidazoles through phenacyl azides in deep eutectic solvents

• Paola Vitale,
• Luciana Cicco,
• Ilaria Cellamare,
• Filippo M. Perna,
• Antonio Salomone and
• Vito Capriati

Beilstein J. Org. Chem. 2020, 16, 1915–1923, doi:10.3762/bjoc.16.158

• by dehydration. The two tautomers 3/3' would most probably originate by two competitive pathways (a and b; Scheme 4) via a [1,5]-hydrogen shift [28][29]. Hydrogen-bond catalysis promoted by DES components may be playing an important role in favoring the loss of nitrogen under mild conditions from a

On the hydrolysis of diethyl 2-(perfluorophenyl)malonate

• Ilya V. Taydakov and
• Mikhail A. Kiskin

Beilstein J. Org. Chem. 2020, 16, 1863–1868, doi:10.3762/bjoc.16.153

• ) is not suitable for the preparation of 2-(perfluorophenyl)malonic acid (2), due to its thermal instability and strong tendency to decarboxylation. We believed, that di-tert-butyl 2-(perfluorophenyl)malonate or dibenzyl 2-(perfluorophenyl)malonate, which are cleaving under very mild conditions are

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

• reaction of CSI with epoxides in different solvents under mild conditions and compared the reaction mechanism with previously proposed mechanisms using theoretical calculations. Keshava Murthy and Dhar [41] postulated a mechanism involving a zwitterionic intermediate. C–O bond cleavage in this unstable and

• shorter reaction times under mild conditions using a simple purification method. Apparently, our protocol describes a reasonable methodology for the conversion of epoxides to protected 1,2-diols and 2-amino alcohols. Attention is drawn on these 1,2-oxygen and/or nitrogen units since they are present in

• . Conclusion In summary, in the first part of the study, we have improved the general synthesis of five-membered cyclic carbonates and oxazolidinones from various epoxides under mild conditions. We also described the synthesis of novel oxazolidinone derivatives 8i and 8j and 1,3-dioxolan-2-ones 9c and 9i

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

• previous functionalization, thus considerably reduce waste generation and a number of synthetic steps. In parallel, transformations involving photoredox catalysis promote radical reactions in the absence of radical initiators. They are conducted under particularly mild conditions while using the visible

• -transfer-type reactions under mild conditions and in the absence of toxic radical precursors [44][45][46]. Considering, on one hand, the fundamentally appealing properties of both, metal-catalyzed C–H functionalization reactions and visible-light-induced photocatalysis, and, on the other hand, their

• combination of photocatalysis and metal-catalyzed C–H activations upholds the desired couplings under, usually, mild conditions and at room temperature, while utilization of non-prefunctionalized coupling partners reduces the waste formation. Last but not least, the use of visible light, one of the most

Tuneable access to indole, indolone, and cinnoline derivatives from a common 1,4-diketone Michael acceptor

• Dalel El-Marrouki,
• Sabrina Touchet,
• Abderrahmen Abdelli,
• Hédi M’Rabet,
• Mohamed Lotfi Efrit and
• Philippe C. Gros

Beilstein J. Org. Chem. 2020, 16, 1722–1731, doi:10.3762/bjoc.16.144

• ; indoles 6, indolones 7, and cinnolines 8, starting from common substrates 1,4-diketones 5 and primary amines. The protocols developed here used mild conditions, were functional-group tolerant, transition-metal-free, proceeded in moderate to good yield, and could therefore easily be used in medicinal

Clickable azide-functionalized bromoarylaldehydes – synthesis and photophysical characterization

• Dominik Göbel,
• Marius Friedrich,
• Enno Lork and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2020, 16, 1683–1692, doi:10.3762/bjoc.16.139

• . Condensation with 2-amino-2-methylpropan-1-ol and oxidation with NBS yielded oxazoline 6 in a good yield. Directed ortho-metalation utilizing TMPMgCl·LiCl under mild conditions and subsequent smooth formylation with DMF afforded benzaldehyde 7 (see Scheme 2). Due to rapid decomposition of 7 under ambient and

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

• provides access to cyclopentenones from accessible starting materials under relatively mild conditions. The increasing demand of fine chemicals bearing fluorine atoms at strategic positions, together with the ubiquitous presence of the cyclopentenone ring in added-value compounds, has attracted researchers

Mechanochemical green synthesis of hyper-crosslinked cyclodextrin polymers

• Alberto Rubin Pedrazzo,
• Fabrizio Caldera,
• Marco Zanetti,
• Silvia Lucia Appleton,
• Nilesh Kumar Dhakar and
• Francesco Trotta

Beilstein J. Org. Chem. 2020, 16, 1554–1563, doi:10.3762/bjoc.16.127

• -CDI 1:8 based on elemental analysis; see Table 1 for details). No appreciable differences in color or in ζ potential were observed. The presence of reactive imidazole was therefore crucial for this type of easy functionalization under mild conditions. The βNS-CDI 1:8 samples after reaction with the

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

• photon and mass transport. Photocatalysis provides a unique route to carry out complex chemical transformations under mild conditions that are often impossible with “standard” organic synthetic procedures. The earliest report of synthetic photochemistry can be traced back to Trommsdorf in 1834, who

In silico rationalisation of selectivity and reactivity in Pd-catalysed C–H activation reactions

• Liwei Cao,
• Mikhail Kabeshov,
• Steven V. Ley and
• Alexei A. Lapkin

Beilstein J. Org. Chem. 2020, 16, 1465–1475, doi:10.3762/bjoc.16.122

• mild conditions [13]. In particular, reactions involving palladium-catalysed activation of sp2 or sp3 C–H bonds of arenes or alkanes have been extensively investigated due to their wide scope and functional group tolerance [14]. A number of different mechanisms are proposed in the literature