Gold-catalyzed post-Ugi alkyne hydroarylation for the synthesis of 2-quinolones

• Xiaochen Du,
• Jianjun Huang,
• Anton A. Nechaev,
• Ruwei Yao,
• Jing Gong,
• Erik V. Van der Eycken,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2018, 14, 2572–2579, doi:10.3762/bjoc.14.234

• concomitantly promoted the competing alkoxylation reaction (Table 3, entries 1 and 2). Consequently, we were able to isolate and characterize the corresponding TFE-adduct 9c (Table 3, entry 2). Switching to HFIP as the solvent prevented the alkoxylation but led to an even slower reaction rate (Table 3, entries

• in TFE did not lead to a full conversion within 12 h at rt (Table 4, entry 1). Switching to branched fluorinated solvents led to a faster conversion of 7r simultaneously suppressing the competing alkoxylation (Table 4, entries 2–4). Nonetheless, the transformation of 7r was further complicated by the

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• implement a switching unit into the molecular framework, which is reversibly addressable by external stimuli [12][13]. A variety of different stimuli to control MIMs has been reported ranging, for example, from physical stimuli such as electrons, light, temperature, pressure, or magnetism to chemical

• fully reversible and have surprisingly low oxidation potentials (0.37 and 0.74 V vs Ag/AgCl in CH3CN) [24], which enable an easily achievable electrochemical switching under ambient conditions. The stability of all oxidation states – even in the presence of air and moisture – is crucial for the

• -electron-poor molecule. The electrochemical switching of a TTF unit and the change of electronic or conformational properties not necessarily results in a mechanical motion of a MIM. A prerequisite is that at least one of the above-mentioned properties of TTF is interacting with other parts of the MIM. If

A pyridinium/anilinium [2]catenane that operates as an acid–base driven optical switch

• Sarah J. Vella and
• Stephen J. Loeb

Beilstein J. Org. Chem. 2018, 14, 1908–1916, doi:10.3762/bjoc.14.165

• measurements (<5 ppm) confirming the catenated nature of the structure. Table 2 summarizes the observed values. Acid–base driven switching The analysis of the 1H NMR spectrum (CD3CN, 298 K) of [8DB24C8]6+ indicates that the DB24C8 ring resides exclusively at the bis(pyridinium)ethane recognition site. This is

• molecular switching previously observed for analogous [2]rotaxanes. Experimental General comments 4-Bromobenzyl bromide, 4-bromoaniline, 4-pyridylboronic acid, 1,3-dichlorobenzene, p-tolylmagnesium bromide, n-butyllithium and N-bromosuccinimide were purchased from Aldrich and used as received. Benzoyl

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• coupling reaction of 42 occurred at the 4-position, as in the case mentioned above, to give 46 in 44% yield along with the desired product and its N7 isomer. In contrast, switching the protecting group of 27 at the 5-position to TBS resulted in the exclusive formation of 45 reacted at the 1-position (28

Recent advances in phosphorescent platinum complexes for organic light-emitting diodes

• Cristina Cebrián and
• Matteo Mauro

Beilstein J. Org. Chem. 2018, 14, 1459–1481, doi:10.3762/bjoc.14.124

• solution. On the contrary, they became strong emitters in the solid state owing to the switching of the nature of the excited state that becomes 3MMLCT in nature. Their EL properties were evaluated by fabrication of non-doped OLEDs. Compound 10 was embedded into an OLED device with the following

Cobalt–metalloid alloys for electrochemical oxidation of 5-hydroxymethylfurfural as an alternative anode reaction in lieu of oxygen evolution during water splitting

• Jonas Weidner,
• Stefan Barwe,
• Kirill Sliozberg,
• Stefan Piontek,
• Justus Masa,
• Ulf-Peter Apfel and
• Wolfgang Schuhmann

Beilstein J. Org. Chem. 2018, 14, 1436–1445, doi:10.3762/bjoc.14.121

• for 2 h. The mixture was then heated to 1100 °C and hold for 15 h. Subsequently, the bulk material was cooled down by switching off the furnace. The product was obtained in form of a purple metallic ingot. Electrochemical measurements Electrode preparation Nickel RDEs (Ø = 3 mm) were polished

Iodine(III)-mediated halogenations of acyclic monoterpenoids

• Laure Peilleron,
• Tatyana D. Grayfer,
• Joëlle Dubois,
• Robert H. Dodd and
• Kevin Cariou

Beilstein J. Org. Chem. 2018, 14, 1103–1111, doi:10.3762/bjoc.14.96

• our previous study on the bromination of enamides [11]. Thus, using a slight excess of DIB along with a two-fold amount of lithium bromide at 0 °C in dry acetonitrile rapidly yielded dibromo adduct 2a in 91% yield (Table 1, entry 1). Switching the reaction conditions to bromo(trifluoro)acetoxylation

• combination of DIB and iron(III) chloride in a 1.2:0.8 ratio (i.e., a 1:1 OAc/Cl ratio [12]) in acetonitrile, allylic chloride 6a [17] was obtained with a moderate 45% yield (Table 1, entry 11). Switching to a combination of PIFA and TBACl (Table 1, entry 12) did not change the course of the reaction towards

Fluorocyclisation via I(I)/I(III) catalysis: a concise route to fluorinated oxazolines

• Felix Scheidt,
• Christian Thiehoff,
• Gülay Yilmaz,
• Stephanie Meyer,
• Constantin G. Daniliuc,
• Gerald Kehr and
• Ryan Gilmour

Beilstein J. Org. Chem. 2018, 14, 1021–1027, doi:10.3762/bjoc.14.88

• less effective than DCE (Table 1, entries 7–9), switching to DCM led to full consumption of the starting material and a quantitative NMR yield (Table 1, entry 10). In a final optimisation round, the catalyst loading was reduced to 10 mol % with no discernable effect on performance (Table 1, entry 11

Correlation effects and many-body interactions in water clusters

• Andreas Heßelmann

Beilstein J. Org. Chem. 2018, 14, 979–991, doi:10.3762/bjoc.14.83

• ) method [72]). Thus, the decrease of the two-body interaction energy and the increase of the many-body interaction when switching from the cage/prism form to the ring form of (H2O)6 almost cancel. Apparently, the water hexamer is the first cluster where the two-body interactions start to dominate the

An efficient and facile access to highly functionalized pyrrole derivatives

• Meng Gao,
• Wenting Zhao,
• Hongyi Zhao,
• Ziyun Lin,
• Dongfeng Zhang and
• Haihong Huang

Beilstein J. Org. Chem. 2018, 14, 884–890, doi:10.3762/bjoc.14.75

• choice even the reaction time was prolonged to 2 h (36% yield, Table 2, entry 3). Switching the base Et3N to DBU resulted in a significant decrease of product yield (Table 2, entry 4). Given that the crude azomethine ylide 9a was used without any purification, and 9a might be sensitive to other

A stereoselective and flexible synthesis to access both enantiomers of N-acetylgalactosamine and peracetylated N-acetylidosamine

• Bettina Riedl and
• Walther Schmid

Beilstein J. Org. Chem. 2018, 14, 856–860, doi:10.3762/bjoc.14.71

• stereocenter on C4, resulting in the desired cis-selective epoxide opening and therefore, galacto-configured azido alcohols 7a and 7b (≥95% de) [22]. Initial limitations in reaction size and yield could have been overcome by switching the solvent from THF, as described in the Miyashita protocol, to EtOH. This

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• switching procedures can be prevented. Although this requires still much development, it is to be expected that in the near future nanoreactors will be key to a more sustainable production of fine chemicals. Assembly of catalyst-functionalized amphiphilic block copolymers into polymer micelles and vesicles

Stimuli-responsive oligonucleotides in prodrug-based approaches for gene silencing

• Françoise Debart,
• Christelle Dupouy and
• Jean-Jacques Vasseur

Beilstein J. Org. Chem. 2018, 14, 436–469, doi:10.3762/bjoc.14.32

• this purpose various different approaches have been reported for the control of RNA translation (such as RNAi [81][82][83] and antisense [84][85], including splice switching of pre-mRNA [86] and DNAzymes [82][87]) and for the control of gene transcription (such as antigene strategy [88] and decoys [86

Fluorogenic PNA probes

• Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

• background and good response with DNA, as well as offering an excellent specificity [65]. In addition to fluorophore-quencher interactions, FRET [66] and pyrene monomer–excimer switching [67][68] have been employed as alternative mechanisms for inducing fluorescence changes in the DNA probes. The FRET and

• monomer–excimer switching approaches have some advantages over fluorescence quenching because of the large Stokes shifts and the ability to measure the signals at two different wavelengths, thereby providing a means for self-referencing. Furthermore, unlike the fluorophore-quencher beacons, the FRET and

• monomer–excimer switching beacons are also fluorescent in the unbound state, and therefore it is possible to monitor the success of cellular delivery. In the case of pyrene monomer–excimer switching, the long fluorescence lifetime of the pyrene excimers allows facile elimination of background signals from

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• para-benzylic position of the hydroxy group (Scheme 32). It is notable that the bulky tert-butyl group was introduced to suppress side reactions, which could be removed under acidic conditions. The solvent was critical in terms of product switching; the trifluoromethylation of aromatic C–H occurred in

Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial

• Tamara Šmidlehner,
• Ivo Piantanida and
• Gennaro Pescitelli

Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5

• ) into the cell. To mix the solution in the cell, spin it by switching on the motor for a few seconds. Turn off the spinning and record the spectrum. Then, turn on the spinning up to 5000 rpm and record another spectrum. Subtract the non-spinning spectrum from the spinning spectrum to get the LD spectrum

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• intermediate 21 was also considered. This, however, was declared unlikely as it was observed that the reaction needed continuous irradiation to proceed efficiently. Unfortunately, Dolbier and co-workers demonstrated in 2015 that this catalytic system was inefficient when switching the substrates to electron

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

Reagent-controlled regiodivergent intermolecular cyclization of 2-aminobenzothiazoles with β-ketoesters and β-ketoamides

• Irwan Iskandar Roslan,
• Kian-Hong Ng,
• Gaik-Khuan Chuah and
• Stephan Jaenicke

Beilstein J. Org. Chem. 2017, 13, 2739–2750, doi:10.3762/bjoc.13.270

• and amides have been developed, controlled by the reagents employed. With the Brønsted base KOt-Bu and CBrCl3 as radical initiator, benzo[d]imidazo[2,1-b]thiazoles are synthesized via attack at the α-carbon and keto carbon of the β-ketoester moiety. In contrast, switching to the Lewis acid catalyst

• ][12][13] with leaving groups, thus switching to an electrophile [14][15][16], or convert to an α-radical carbon with an oxidant [17][18][19]. β-Ketoesters are also inexpensive, abundant and commercially available, making them attractive substrates. In our continuing effort to develop green and atom

• was not formed with KHCO3 (Table 1, entry 1). Instead, the N-acetylated side product 4 was obtained in moderate yields, together with trace amounts of the benzo[4,5]thiazolo[3,2-a]pyrimidin-4-one side product 5a. Even after switching to the stronger bases K2CO3 and K3PO4, only poor yields of 3a were

A Brønsted base-promoted diastereoselective dimerization of azlactones

• Danielle L. J. Pinheiro,
• Gabriel M. F. Batista,
• Pedro P. de Castro,
• Leonã S. Flores,
• Gustavo F. S. Andrade and
• Giovanni W. Amarante

Beilstein J. Org. Chem. 2017, 13, 2663–2670, doi:10.3762/bjoc.13.264

• . Although no trichloromethylation product was observed, we found out that by switching the solvent, the isolated major product comes from dimerization of azlactones. At this point, we turned our attention towards this product, envisioning the development of an atom-economic reaction for stereoselective C–C

Preparation and isolation of isobenzofuran

• Morten K. Peters and
• Rainer Herges

Beilstein J. Org. Chem. 2017, 13, 2659–2662, doi:10.3762/bjoc.13.263

• : Analytical equipment and methods, experimental procedures and NMR spectra. Acknowledgements The authors gratefully acknowledge funding from the collaborative research center SFB 677 Function by Switching.

Synthesis of naturally-derived macromolecules through simplified electrochemically mediated ATRP

• Paweł Chmielarz,
• Tomasz Pacześniak,
• Katarzyna Rydel-Ciszek,
• Izabela Zaborniak,
• Paulina Biedka and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2017, 13, 2466–2472, doi:10.3762/bjoc.13.243

• elimination of chemical reducing agents, catalyst recycle possibility, and an option to receive polymers with narrow MWD [55][56]. Additionally, application of external stimuli offered a possibility of temporal control, such as the stopping and restarting of the polymerization by switching the “off” and “on

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• the procedure (switching from Gilman’s reagent to aryl lithiocyanocuprates), this method was successfully extended to a wide range of acyclic α-chlorooximes 1 (Scheme 19, reaction (2)). Interestingly, the aryl group, not the cyanide anion is transferred from aryl lithiocyanocuprates to a nitrosoalkene

A mechanochemical approach to access the proline–proline diketopiperazine framework

• Nicolas Pétry,
• Hafid Benakki,
• Eric Clot,
• Pascal Retailleau,
• Farhate Guenoun,
• Fatima Asserar,
• Chakib Sekkat,
• Thomas-Xavier Métro,
• Jean Martinez and
• Frédéric Lamaty

Beilstein J. Org. Chem. 2017, 13, 2169–2178, doi:10.3762/bjoc.13.217

• by mixing an equimolar amount of the starting materials together with a base (K2CO3) in a vibratory ball mill at 25 Hz (Table 2, entry 2). This resulted in a lower conversion compared to that obtained in solution. Using an excess of base increased the conversion to 62% (Table 2, entry 3). Switching

The effect of milling frequency on a mechanochemical organic reaction monitored by in situ Raman spectroscopy

• Patrick A. Julien,
• Ivani Malvestiti and
• Tomislav Friščić

Beilstein J. Org. Chem. 2017, 13, 2160–2168, doi:10.3762/bjoc.13.216

• when ball milling at 27.5 Hz and 30 Hz, compared to milling at frequencies of 20 Hz and 22.5 Hz, while milling at an intermediate frequency of 25 Hz led to irreproducible behavior. Tentatively, we interpret such switching between reactivity profiles by adopting the assumption that mechanochemical