Rearrangement of o-(pivaloylaminomethyl)benzaldehydes: an experimental and computational study

• Csilla Hargitai,
• Györgyi Koványi-Lax,
• Tamás Nagy,
• Péter Ábrányi-Balogh,
• András Dancsó,
• Gábor Tóth,
• Judit Halász,
• Angéla Pandur,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2020, 16, 1636–1648, doi:10.3762/bjoc.16.136

• upfield aromatic δH(7) value (5.71 ppm) was measured for the isoindoline moiety of this compound, i.e., a diamagnetic shift of ca. 1.8 ppm occurred in this position. In order to explain this phenomenon, we should consider the anisotropic effect of the aromatic rings. Such steric arrangement is only

• , and recrystallized from EtOAc/hexane to afford the title compounds as white solids. N-[(5-Formyl-2H-1,3-benzodioxol-4-yl)methyl]-2,2-dimethylpropanamide (2a) [1]. Method A: This compound was prepared according to general procedure I using 1a [2] (1.02 g, 3.88 mmol) and TFA (30 µL, 44 mg, 0.39 mmol

• C14H17NO4 (263.29): N, 5.32; H, 6.51; C, 63.87; found: N, 5.38; H, 6.44; C, 63.77%; NMR data are identical with those published earlier [1]. Method B: This compound was prepared according to general procedure II using 1a [2] (1.00 g, 3.80 mmol) and TFA (29 µL, 43 mg, 0.38 mmol). The title compound (592 mg

Antibacterial scalarane from Doriprismatica stellata nudibranchs (Gastropoda, Nudibranchia), egg ribbons, and their dietary sponge Spongia cf. agaricina (Demospongiae, Dictyoceratida)

• Cora Hertzer,
• Stefan Kehraus,
• Nils Böhringer,
• Fontje Kaligis,
• Robert Bara,
• Dirk Erpenbeck,
• Gert Wörheide,
• Till F. Schäberle,
• Heike Wägele and
• Gabriele M. König

Beilstein J. Org. Chem. 2020, 16, 1596–1605, doi:10.3762/bjoc.16.132

• of this compound. In general, scalarane sesterterpenes are bioactive metabolites, mainly isolated from marine sources, such as Dictyoceratida sponges and the nudibranchs that feed on them [7][25][29][33][56]. So far, only six scalaranes containing cyclopropane rings, constructed of C-4, C-19 and C-20

4-Hydroxy-3-methyl-2(1H)-quinolone, originally discovered from a Brassicaceae plant, produced by a soil bacterium of the genus Burkholderia sp.: determination of a preferred tautomer and antioxidant activity

• Dandan Li,
• Naoya Oku,
• Yukiko Shinozaki,
• Yoichi Kurokawa and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1489–1494, doi:10.3762/bjoc.16.124

• -hydroxy-3-methyl-2(1H)-quinolone (1, Figure 1). This compound was recently reported from the root of woad (Isatis tinctoria, family Brassicaceae) with no details of structure characterization [17]. Herein we describe the isolation, unequivocal structure characterization, and antioxidant activity of

Synthesis and properties of quinazoline-based versatile exciplex-forming compounds

• Rasa Keruckiene,
• Simona Vekteryte,
• Ervinas Urbonas,
• Matas Guzauskas,
• Eigirdas Skuodis,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 1142–1153, doi:10.3762/bjoc.16.101

• ) which is usually detected for materials exhibiting low-intensity emissions [22][23]. Exciplex-forming properties Since compound 1 was characterized by the most blue-shifted fluorescence in the solid-state and a high first triplet energy level of 2.97 eV (Figure 5a and Figure 7a), this compound was

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• capture therapy (BNCT) [53][88][89][90][91][92]. This compound was used for PET imaging of melanoma in animal models. The low affinity of 178 for the ʟ-type amino acid transporter1 (LAT1), however, limited the use of this compound as PET radiotracer for brain tumor imaging [93][94][95][96]. Therefore, for

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

• values were estimated as 2.54 eV for 4, and 2.67 eV for 3 and 6. The triplet energy could not be estimated for derivative 5, since the phosphorescence at 77 K was practically undetectable for this compound. Electrochemical and photoelectrical properties The electrochemical properties of the acridane

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates

• Phil M. Pithan,
• Sören Steup and
• Heiko Ihmels

Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82

• photochromism, i.e., a blue shift of the absorption maximum of the merocyanine form [5][19][27][28][29], and increased stability of the latter towards the thermal back reaction [21][28][30][31][32][33][34]. In this context, the complexation of metal cations has also been exploited to utilize this compound class

Synthesis of disparlure and monachalure enantiomers from 2,3-butanediacetals

• Adam Drop,
• Hubert Wojtasek and
• Bożena Frąckowiak-Wojtasek

Beilstein J. Org. Chem. 2020, 16, 616–620, doi:10.3762/bjoc.16.57

• ensure the required configuration of the asymmetric centers determining the biological activity of this compound. They include the use of naturally occurring chiral substrates, such as ʟ-glutamic acid [13], ʟ-tartaric acid [14][15][16], ᴅ-glucose [17], and sorbitol [18] as starting materials, as well as

• –8 are obtained. We therefore decided to apply this compound for the synthesis of both enantiomers of disparlure and both enantiomers of monachalure. Results and Discussion Compound 14 was prepared and converted to 15 by Fukuyama reduction as described previously [37]. The overall yield for the

• 19 instead. This compound was obtained from both aldehyde 15 and its precursor ethyl thioester methyl ester 14, respectively (Scheme 3). Both substrates 14 and 15 were reduced to the corresponding diol 17 with lithium aluminum hydride with 73% or 83% yield, respectively. Next, the selective

Regio- and stereoselective synthesis of new ensembles of diversely functionalized 1,3-thiaselenol-2-ylmethyl selenides by a double rearrangement reaction

• Svetlana V. Amosova,
• Andrey A. Filippov,
• Nataliya A. Makhaeva,
• Alexander I. Albanov and
• Vladimir A. Potapov

Beilstein J. Org. Chem. 2020, 16, 515–523, doi:10.3762/bjoc.16.47

• % yields, respectively. The one-pot synthesis of hitherto unknown bis(1,3-thiaselenol-2-ylmethyl) diselenide (8) in 90% yield from thiaselenole 1 was developed (Scheme 10). The reaction proceeded via the formation of thiaselenole selenocyanate 4, which was in situ converted into diselenide 8. This compound

Visible-light-induced addition of carboxymethanide to styrene from monochloroacetic acid

• Kaj M. van Vliet,
• Nicole S. van Leeuwen,
• Albert M. Brouwer and
• Bas de Bruin

Beilstein J. Org. Chem. 2020, 16, 398–408, doi:10.3762/bjoc.16.38

• traditional reactivity of this compound. Here, we investigated the possibility of applying monochloroacetic acid as a substrate for photoredox catalysis with styrene to directly produce γ-phenyl-γ-butyrolactone. Instead of using nucleophilic substitution, we cleaved the carbon chlorine bond by single-electron

• monochloroacetic acid have been published. The production of basic building blocks like glycine [5] (>600 000 tons/year in China in 2015) and diethyl malonate from monochloroacetic acid show the value of this compound as a starting material. Many reactions with monochloroacetic acid, including the synthesis of

The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

• Narasimhamurthy Rajeev,
• Toreshettahally R. Swaroop,
• Ahmad I. Alrawashdeh,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Seegehalli M. Anil,
• Kuppalli R. Kiran,
• Chandra,
• Paris E. Georghiou,
• Kanchugarakoppal S. Rangappa and
• Maralinganadoddi P. Sadashiva

Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

• of the final products were detected in the NMR spectra, and a representative DFT computational analysis conducted with 4c (this compound also yielded a crystal structure) was in agreement with the ratio of the two rotamers that were observed in the corresponding NMR spectra. A mechanism was proposed

Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

• Afef Mabrouki,
• Malek Fouzai,
• Armand Soldera,
• Abdelkader Kriaa and
• Ahmed Hedhli

Beilstein J. Org. Chem. 2020, 16, 149–158, doi:10.3762/bjoc.16.17

• , compared to two-chain and shorter-chain homologues. Taking into account these observations, the inability of 2d to exhibit mesophases becomes axiomatic, since this compound is devoid of any terminal alkyl chain. X-ray patterns analysis In order to correlate the obtained results from POM and DSC, we have

Synthesis and characterization of bis(4-amino-2-bromo-6-methoxy)azobenzene derivatives

• David Martínez-López,
• Amirhossein Babalhavaeji,
• Diego Sampedro and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2019, 15, 3000–3008, doi:10.3762/bjoc.15.296

• (i.e., a 2-bromo-6-methoxy substitution pattern) was found to lower the pKa of the azonium ion such that it fell outside the normal physiological range. The neutral version of this compound nevertheless underwent trans-to-cis photoisomerization in the presence of blue-green light and exhibited slow

Pigmentosins from Gibellula sp. as antibiofilm agents and a new glycosylated asperfuran from Cordyceps javanica

• Soleiman E. Helaly,
• Wilawan Kuephadungphan,
• Patima Phainuphong,
• Mahmoud A. A. Ibrahim,
• Kanoksri Tasanathai,
• Suchada Mongkolsamrit,
• Janet Jennifer Luangsa-ard,
• Souwalak Phongpaichit,
• Vatcharin Rukachaisirikul and
• Marc Stadler

Beilstein J. Org. Chem. 2019, 15, 2968–2981, doi:10.3762/bjoc.15.293

• were found to produce the same compound. So far, pigmentosin A (1) was reported only from lichenized fungi [20][21], and thus this is the first report of this compound stemming from another group of fungi. Recently, we have reported on the two new β-carboline alkaloid derivatives gibellamines A and B

• , respectively. Notably, 1 also weakly inhibited proliferation of HeLa KB3.1 cells, with an IC50 of 17 μg/mL. This compound was reported by Grove and co-workers [32] to be active against B. subtilis (MIC 20 μg/mL). Although both compounds showed neither nematicidal activity against C. elegans nor antibiofilm

Synthesis and optoelectronic properties of benzoquinone-based donor–acceptor compounds

• Daniel R. Sutherland,
• Nidhi Sharma,
• Georgina M. Rosair,
• Ifor D. W. Samuel,
• Ai-Lan Lee and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2019, 15, 2914–2921, doi:10.3762/bjoc.15.285

• -shifted compared to those found for 2 and 5. Charge-transfer was expected to be weaker in compound 4, where the donor groups were meta disposed with respect to the acceptor. Indeed, there was only a very poorly absorptive CT band at 370 nm for this compound, which reflected the poor conjugation between

Influence of the cis/trans configuration on the supramolecular aggregation of aryltriazoles

• Sara Tejera,
• Giada Caniglia,
• Rosa L. Dorta,
• Andrea Favero,
• Javier González-Platas and
• Jesús T. Vázquez

Beilstein J. Org. Chem. 2019, 15, 2881–2888, doi:10.3762/bjoc.15.282

• °C in a refrigerator. This temperature gave rise to an opaque gel that melted above 18 °C (Table 2). The same approach, along with reduction of the minimum gelation concentration to 1.1% w/w (in DMSO) was used to obtain a gel based on 8f. In addition, this compound proved to be an effective

• as between the triazole rings, and therefore the presence of multiple intermolecular π–π stacking and π–bromine [19] interactions. This compound precipitated in the presence of any amount of water and gelled only in DMSO at a low temperature. Compound 10 produced pseudo-crystals in DMSO/H2O (1:1, v/v

• , in black), identical to those obtained for this compound in CH3CN [15], although of lower intensity. On the other hand, the ECD spectrum of the gel instead exhibited a normal Cotton effect at 253 nm (Δε = −3.8), which, at the same time, was the wavelength of its absorption maximum (Figure 6, in blue

Skeletocutins M–Q: biologically active compounds from the fruiting bodies of the basidiomycete Skeletocutis sp. collected in Africa

• Tian Cheng,
• Clara Chepkirui,
• Cony Decock,
• Josphat C. Matasyoh and
• Marc Stadler

Beilstein J. Org. Chem. 2019, 15, 2782–2789, doi:10.3762/bjoc.15.270

• the cultures of the same fungus (i.e., the corresponding mycelial culture of the specimen that was the subject of the present study [4]) and originally from Tyromyces lacteus [6]. In these two cases, 6 was reported to be the major component of the culture extracts. Even though this compound is

• µg/mL at 50 and 110 µM substrate concentration. Although tyromycin A (6) was previously reported to be active in a similar assay against HeLa S3 cells, with IC50 values of 31 μg/mL at 50 μM substrate concentration, an IC50 value >150 μg/mL for this compound was recorded on the HeLa (KB3.1) cells

A combinatorial approach to improving the performance of azoarene photoswitches

• Joaquin Calbo,
• Aditya R. Thawani,
• Rosina S. L. Gibson,
• Andrew J. P. White and
• Matthew J. Fuchter

Beilstein J. Org. Chem. 2019, 15, 2753–2764, doi:10.3762/bjoc.15.266

• -fluoroazopyrazole as part of their study of the supramolecular chemistry of these systems. Irradiating their compound at 365 nm enables near quantitative E→Z conversion, however, the 520 nm PSS provides 55% of the E-isomer. In water, this compound possesses a thermal half-life of >11 days. Herein, we present

• supra) due to the ortho-methoxy groups, which likely explains the inaccuracy of the computational predictions for this compound. The experimental π–π* band for all compounds undergoes a blue shift upon isomerization E to Z, also in good accord with the theoretical predictions (Figure 8, Table S1 and S2

Synthetic terpenoids in the world of fragrances: Iso E Super^® is the showcase

• Alexey Stepanyuk and
• Andreas Kirschning

Beilstein J. Org. Chem. 2019, 15, 2590–2602, doi:10.3762/bjoc.15.252

• assigned as C13H20O [10]. In an attempt to recreate this compound by condensation of acetone with citral (28) a compound with “a strange but not very characteristic odour” was formed, later named pseudoionone (29, Scheme 1). It turned out not to be suited for further investigations. However, after cleaning

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• examples that state the metathesis of internal propargylic systems being particularly challenging [13][96][97]. As the [10]ferrocenophane 2a can be obtained reliably and selectively from the RCAM reaction, additional electrochemical and chemical studies were performed on this compound. To resolve the

Effect of ring size on photoisomerization properties of stiff stilbene macrocycles

• Sandra Olsson,
• Óscar Benito Pérez,
• Magnus Blom and
• Adolf Gogoll

Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233

• photodynamic properties of this compound have been reported previously [27]. The E- and Z-isomers give distinctively separated chemical shifts for the CH2 protons next to the double bond. This makes the determination of the Z/E ratio straightforward. The composition of the photostable mixtures as compared to

Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms

• A. Lennart Schleper,
• Mariano L. Bossi,
• Vladimir N. Belov and
• Stefan W. Hell

Beilstein J. Org. Chem. 2019, 15, 2344–2354, doi:10.3762/bjoc.15.227

• switching cycles in acetonitrile solution while losing only ca. 15% of its absorption. The extrapolation of the change in absorption yielded about 340 switching cycles, until a 50% signal loss occurs. Thus, this compound is a good candidate for a marker applicable in STORM/PALM and MINFLUX super-resolution

Small anion-assisted electrochemical potential splitting in a new series of bistriarylamine derivatives: organic mixed valency across a urea bridge and zwitterionization

• Keishiro Tahara,
• Tetsufumi Nakakita,
• Alyona A. Starikova,
• Takashi Ikeda,
• Masaaki Abe and
• Jun-ichi Kikuchi

Beilstein J. Org. Chem. 2019, 15, 2277–2286, doi:10.3762/bjoc.15.220

• sides are almost coplanar with N···N distances between the NAr3 moieties of more than 13 Å (Figure S5 and Table S1 in Supporting Information File 1). Further investigations were not performed for 1c because the solubility of this compound in aprotic solvents including CH2Cl2 were extremely low. The

Aggregation-induced emission effect on turn-off fluorescent switching of a photochromic diarylethene

• Luna Kono,
• Yuma Nakagawa,
• Ayako Fujimoto,
• Ryo Nishimura,
• Yohei Hattori,
• Toshiki Mutai,
• Nobuhiro Yasuda,
• Kenichi Koizumi,
• Satoshi Yokojima,
• Shinichiro Nakamura and
• Kingo Uchida

Beilstein J. Org. Chem. 2019, 15, 2204–2212, doi:10.3762/bjoc.15.217

• is one of the examples which express the mechanisms of aggregation-induced emission (AIE). This compound emits orange fluorescence with a large Stokes shift derived from ESIPT in aprotic solvents such as THF or hexane, while it exhibits only a photochromic reaction in protic solvents such as methanol

1,2,3,4-Tetrahydro-1,4,5,8-tetraazaanthracene revisited: properties and structural evidence of aromaticity loss

• Arnault Heynderickx,
• Sébastien Nénon,
• Olivier Siri,
• Vladimir Lokshin and
• Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2019, 15, 2059–2068, doi:10.3762/bjoc.15.203

• as the most convenient method of preparation (Scheme 1) [8]. This compound was described as yellow plates (from ethanol), which decomposed at about 300 °C giving a small amount of almost colorless crystalline sublimate identified as 1,4,5,8-tetraazaanthracene (5) [8]. The structure of 3 as the