Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• ]. Noël and co-workers reported the C3–H olefination of indoles using Pd(OAc)2 as a catalyst and molecular oxygen as the oxidant under continuous flow conditions [29]. Jia et al. reported the synthesis of 3-alkenylindoles using Pd(OAc)2 as the catalyst and MnO2 as the oxidant under ball milling conditions

Functionalization of the imidazo[1,2-a]pyridine ring in α-phosphonoacrylates and α-phosphonopropionates via microwave-assisted Mizoroki–Heck reaction

• Damian Kusy,
• Agata Wojciechowska,
• Joanna Małolepsza and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 15–21, doi:10.3762/bjoc.16.3

• heterogeneous and homogeneous catalysts, as well as continuous-flow conditions [13][14][15]. Therefore, we tested microwave heating, a technique which is known for significant acceleration of the C–C coupling reaction [16]. We carried out the optimization studies using model substrates – compound 1a and benzyl

Bacterial terpene biosynthesis: challenges and opportunities for pathway engineering

• Eric J. N. Helfrich,
• Geng-Min Lin,
• Christopher A. Voigt and
• Jon Clardy

Beilstein J. Org. Chem. 2019, 15, 2889–2906, doi:10.3762/bjoc.15.283

• mostly chemically indistinguishable, while many P450s are known to selectively act on specific carbon atom(s). A continuous electron input is required to keep CYPs functional [83]. In general, soluble bacterial CYPs utilize class I redox systems, where the electron from NAD(P)H is delivered to CYPs

Emission and biosynthesis of volatile terpenoids from the plasmodial slime mold Physarum polycephalum

• Xinlu Chen,
• Tobias G. Köllner,
• Wangdan Xiong,
• Guo Wei and
• Feng Chen

Beilstein J. Org. Chem. 2019, 15, 2872–2880, doi:10.3762/bjoc.15.281

• continuous darkness. Headspace collection and GC–MS analysis On the 8th day and 18th day after the transfer of plasmodia to a fresh agar plate, volatiles were collected from the headspace of plasmodia on the agar plate using solid phase microextraction (SPME) (https://www.sigmaaldrich.com). After collection

Dyes in modern organic chemistry

• Heiko Ihmels

Beilstein J. Org. Chem. 2019, 15, 2798–2800, doi:10.3762/bjoc.15.272

• examples clearly show that dye chemistry is a mature and essential topic in organic chemistry, it still constitutes a vibrant research area because of the continuous need for specifically designed dyes with custom-made optical properties for diverse topical applications. Hence, this special issue aimed at

• continuous support. Heiko Ihmels Siegen, October 2019

Progress in metathesis chemistry

• Karol Grela and
• Anna Kajetanowicz

Beilstein J. Org. Chem. 2019, 15, 2765–2766, doi:10.3762/bjoc.15.267

• pills are now truly user friendly. Olefin metathesis catalysts can work under homo- or heterogeneous conditions, as well as under continuous flow. The stability of Ru–methylidene species (an attribute important for a successful ethenolysis process) has been significantly improved. Importantly, we have

Unexpected one-pot formation of the 1H-6a,8a-epiminotricyclopenta[a,c,e][8]annulene system from cyclopentanone, ammonia and dimethyl fumarate. Synthesis of highly strained polycyclic nitroxide and EPR study

• Sergey A. Dobrynin,
• Igor A. Kirilyuk,
• Yuri V. Gatilov,
• Andrey A. Kuzhelev,
• Olesya A. Krumkacheva,
• Matvey V. Fedin,
• Michael K. Bowman and
• Elena G. Bagryanskaya

Beilstein J. Org. Chem. 2019, 15, 2664–2670, doi:10.3762/bjoc.15.259

• reflections (Rint 0.0375), R1 0.0439, wR2 0.1215, S 1.011 [for 3451 I > 2σ(I)]. EPR measurements Continuous wave (CW) EPR measurements were carried out using a commercial Bruker Elexsys E540 X-band spectrometer. The CW EPR spectra were simulated using EasySpin [18]. Pulse EPR experiments were carried out

Safe and highly efficient adaptation of potentially explosive azide chemistry involved in the synthesis of Tamiflu using continuous-flow technology

• Cloudius R. Sagandira and
• Paul Watts

Beilstein J. Org. Chem. 2019, 15, 2577–2589, doi:10.3762/bjoc.15.251

• explosive azide chemistry involved in a proposed Tamiflu route by taking advantage of the continuous-flow technology. The azide intermediates were safely synthesised in full conversions and >89% isolated yields. Keywords: azide chemistry; continuous flow synthesis; hazardous; safe; Tamiflu; Introduction

• ) (Scheme 1 and Figure 1). Continuous-flow synthesis offers the generation and consumption of dangerous intermediates in situ preventing their accumulation, thus it represents a potential solution for dealing with hazardous reaction intermediates and products [15]. Additionally, microreactors can handle

• exothermic reactions extremely well, due to the inherent high surface area to volume ratio and rapid heat dissipation [16] unlike the conventional batch process. Continuous-flow production may certainly enhance the green metrics of synthesis in several ways [17] and their work clearly demonstrated the

Chemical synthesis of the pentasaccharide repeating unit of the O-specific polysaccharide from Escherichia coli O132 in the form of its 2-aminoethyl glycoside

• Debasish Pal and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2019, 15, 2563–2568, doi:10.3762/bjoc.15.249

• -acetylation using NaOMe in MeOH followed by hydrogenolysis in a ThalesNano continuous flow hydrogenation assembly using a 10% Pd-C cartridge [29]. After three cycles of hydrogenation, formation of the target pentasaccharide 1 was evident from the mass spectrum (Scheme 4). Conclusion In conclusion, the

In search of visible-light photoresponsive peptide nucleic acids (PNAs) for reversible control of DNA hybridization

• Lei Zhang,
• Greta Linden and
• Olalla Vázquez

Beilstein J. Org. Chem. 2019, 15, 2500–2508, doi:10.3762/bjoc.15.243

• irradiated to obtain maximal cis (oF4Azo, 520 nm, 10 min) or trans (HTI, 405 nm, 2 min) and stored in the dark. PNA12(oF4Azo) (3) was also measured with continuous heating at 90 °C (gray squares). UV–vis spectra were collected at different time points during 10 h. Curves derived were calculate from two

Reversible switching of arylazopyrazole within a metal–organic cage

• Anton I. Hanopolskyi,
• Soumen De,
• Michał J. Białek,
• Yael Diskin-Posner,
• Liat Avram,
• Moran Feller and
• Rafal Klajn

Beilstein J. Org. Chem. 2019, 15, 2398–2407, doi:10.3762/bjoc.15.232

• this notion, we prepared pure Z-1 (by evaporating the solvent from a solution of E-1 in acetonitrile under continuous UV irradiation) and i) confirmed its high solubility in water (see Figure S24 in Supporting Information File 1 for an NMR spectrum of Z-1 in D2O) and ii) demonstrated light-controlled

Excited state dynamics for visible-light sensitization of a photochromic benzil-subsituted phenoxyl-imidazolyl radical complex

• Yoichi Kobayashi,
• Yukie Mamiya,
• Katsuya Mutoh,
• Hikaru Sotome,
• Masafumi Koga,
• Hiroshi Miyasaka and
• Jiro Abe

Beilstein J. Org. Chem. 2019, 15, 2369–2379, doi:10.3762/bjoc.15.229

• fs is the apparent lifetime because the conformational change from the skewed to the planar structure at sub-picosecond time scale induces the continuous spectral shift. Because the present SVD global analyses do not consider the continuous spectral shift, it is difficult to extract the exact time

• ≈2 ps [45]. The similarity of the time constant of the bond breaking to that of EAS1 supports that the C–N bond is cleaved by the direct excitation of the PIC unit. The spectral evolution from EAS2 (1.4 ps) to EAS3 (38 ps, green in Figure 3d) shows the continuous spectral shift due to the benzil unit

• and the increase in the absorption due to the biradical form (660 nm). Because the continuous spectral shift due to the benzil unit is still observed in EAS2 (1.4 ps), it is suggested that the structural change of the benzil unit of Benzil-PIC is somehow slightly decelerated as compared to that of

Current understanding and biotechnological application of the bacterial diterpene synthase CotB2

• Ronja Driller,
• Daniel Garbe,
• Norbert Mehlmer,
• Monika Fuchs,
• Keren Raz,
• Dan Thomas Major,
• Thomas Brück and
• Bernhard Loll

Beilstein J. Org. Chem. 2019, 15, 2355–2368, doi:10.3762/bjoc.15.228

• Ministry of Economic Affairs, Regional Development and Energy for the bioinsecticide project (Grant #1340/68351/13/2013). We are grateful to M. Wahl for continuous encouragement and support.

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

• , agricultural, and materials industries. The incorporation of fluorine-containing groups into organic molecules can improve their chemical and physical properties, which attracts continuous interest in organic synthesis. Among various reported methods, transition-metal-catalyzed fluorination/fluoroalkylation

• dehydrogenation process to afford the target product. Also in 2015, Li and co-workers [146] developed a mild and fast Cu(I/II)-catalyzed trifluoromethylation procedure to obtain 3-trifluoromethylcoumarins. The reaction was carried out with a CuCl/CF3SO2Na/TBHP system under continuous-flow conditions, affording

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

• )-isomers and their absorption maxima appeared blue shifted as demonstrated by the UV–vis spectra extracted from the LC runs. Unfortunately, the amount of photoisomerization was only moderate, since after 100 minutes of continuous irradiation still substantial amounts of the (E)-isomers were present in the

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

• , allowing continuous modification through bond formation and/or breaking. This dynamic nature facilitates reorganisation through the exchange of building blocks, or incorporation of new substituents, even after the initial polymer has been formed [192]. The fulvene DAC is a good candidate for dynamer

Application of chiral 2-isoxazoline for the synthesis of syn-1,3-diol analogs

• Juanjuan Feng,
• Tianyu Li,
• Jiaxin Zhang and
• Peng Jiao

Beilstein J. Org. Chem. 2019, 15, 1840–1847, doi:10.3762/bjoc.15.179

• our continuous efforts in asymmetric syntheses and applications of chiral 2-isoxazolines [49][50][51]. Results and Discussion Our synthesis commenced with a chiral 3,5-disubstituted-2-isoxazoline 3 or 4, which were prepared from silyl nitronate through an asymmetric 1,3-dipolar cycloaddition developed

Synthesis, enantioseparation and photophysical properties of planar-chiral pillar[5]arene derivatives bearing fluorophore fragments

• Guojuan Li,
• Chunying Fan,
• Guo Cheng,
• Wanhua Wu and
• Cheng Yang

Beilstein J. Org. Chem. 2019, 15, 1601–1611, doi:10.3762/bjoc.15.164

• DPA is responsible for the red-shift of the absorption. For P5A-Py, however, adding water to the THF solution led to a continuous red-shifting of the UV–vis spectra and increasing of CD signal, which is reasonable, as the planar structure of Py tends more to get aggregated in water by π–π stacking

Selenophene-containing heterotriacenes by a C–Se coupling/cyclization reaction

• Pierre-Olivier Schwartz,
• Sebastian Förtsch,
• Astrid Vogt,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2019, 15, 1379–1393, doi:10.3762/bjoc.15.138

• slightly less aromatic than thiophenes with increasing number of selenium atoms a continuous decrease of the anodic peak potential was observed going from 2 (0.84 V) over 3 (0.82 V) to 4 (0.80 V). In comparison, dithienopyrrole (DTP), a corresponding nitrogen-bridged 2,2’-bithiophene, with a peak potential

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

• lies outside of the milling chamber where sample can pass in and out for continuous monitoring [48]. This allows for varying milling media with the benefit of in situ measurements. For some processes like reactive aging with enzymes [22], polytetrafluoroethylene (PTFE) jars were preferred over

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

• polyfurfuryl alcohol-supported catalysts for applications in heterogeneous enamine catalysis. The utilization of the polymer-supported catalysts in both batch and continuous-flow organocatalytic procedures proved moderate catalytic efficacy and enantioselectivity, but excellent diastereoselectivity in the

• -supported chiral organocatalysts usually provides a much greener prospect for the synthesis of enantiomerically enriched building blocks [4][5][6]. Importantly, immobilized catalysts allow for both recyclability of the catalyst and the implementation of continuous-flow procedures, which usually encompass

• catalysts for applications in continuous-flow catalysis [8]. In an endeavor to develop a cheaper and renewable polymer-supported organocatalyst, herein we describe the multicomponent synthesis of furfuryl-containing prolyl pseudo-peptide catalysts and their subsequent utilization in the preparation of PFA

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

• continuous phase and crystal aggregates of PCL and CB[7]. At low CB[7] contents, the majority of the CB[7] molecules could disperse homogeneously in the PCL matrix, partly causing the disruption of continuous phase and crystallization of PCL and CB[7]. With the increase of CB[7] content, there are more

• continuous phases of CB[7] and PCL formed in the PCL/CB[7] nanofibers, which causes the formation of more crystal aggregates. DSC measurements can provide valuable information about the thermal transition properties, i.e., phase-transition temperatures and transition enthalpies. Figure 3 shows the first

Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols

• Chi-Tung Yeung,
• Wesley Ting Kwok Chan,
• Wai-Sum Lo,
• Ga-Lai Law and
• Wing-Tak Wong

Beilstein J. Org. Chem. 2019, 15, 955–962, doi:10.3762/bjoc.15.92

• structure with continuous and alternative inter- and intramolecular hydrogen bonds, whereas 6 forms a monomer without intermolecular hydrogen bonds for supramolecular formation. Together with compounds 1, 2 and 5, all were found to be active organocatalysts in oxo-DA reactions, with 2 resulting in the

Azologization of serotonin 5-HT₃ receptor antagonists

• Karin Rustler,
• Galyna Maleeva,
• Piotr Bregestovski and
• Burkhard König

Beilstein J. Org. Chem. 2019, 15, 780–788, doi:10.3762/bjoc.15.74

• solution resulting in a fast exchange of the surrounding media and co-applied tested compounds. Thus, the cis-PSS of 16c might not be reached by irradiation within the short time of compound application despite continuous irradiation. Therefore, two azobenzene-extended derivatives (23 and 28) with improved

Synthesis of functionalized diazocines for application as building blocks in photo- and mechanoresponsive materials

• Widukind Moormann,
• Daniel Langbehn and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 727–732, doi:10.3762/bjoc.15.68

• ’-diaminodiazocine 2 (center) and 4,4’-diaminodiazocine 3 (right). Continuous lines: 100% cis and dashed lines: PSS (385 nm) at 298.15 K in acetonitrile. Synthesized target diazocines 4–7 for applications in responsive materials. UV–vis spectra of 3,3’-diaminodiazocine 2 (left), 3,3’-di(aminomethyl)diazocine 6a

• (center), and 3,3’-di(aminoethyl)diazocine 6b (right). Continuous lines: 100% cis and dashed lines: PSS (385 nm) at 298.15 K in acetonitrile. Key reactions in diazocine synthesis. Syntheses of the functionalized diazocines 4–7. Reaction conditions: i) Isobutylene, sulfuric acid, DCM; ii) t-BuOK, Br2, THF