Synthesis of aryl-substituted thieno[3,2-b]thiophene derivatives and their use for N,S-heterotetracene construction

• Nadezhda S. Demina,
• Nikita A. Kazin,
• Nikolay A. Rasputin,
• Roman A. Irgashev and
• Gennady L. Rusinov

Beilstein J. Org. Chem. 2019, 15, 2678–2683, doi:10.3762/bjoc.15.261

• -phenylthiophene-2-carboxylate (1a) with sodium nitrite in aqueous HCl or HBr solution failed due to the poor solubility of its hydrohalide salts, while when 3-amino ester 1a was treated with tert-butyl nitrite and CuBr2 in acetonitrile solution, we observed only significant decomposition of starting compound. In

AgNTf₂-catalyzed formal [3 + 2] cycloaddition of ynamides with unprotected isoxazol-5-amines: efficient access to functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives

• Ziping Cao,
• Jiekun Zhu,
• Li Liu,
• Yuanling Pang,
• Laijin Tian,
• Xuejun Sun and
• Xin Meng

Beilstein J. Org. Chem. 2019, 15, 2623–2630, doi:10.3762/bjoc.15.255

• proceed efficiently with 3,4-dimethylisoxazol-5-amine (8f), thus a mixture of unidentifiable decomposition products was observed. In order to investigate the feasibility of the present reaction on a large scale, a gram-grade experiment was performed (Scheme 4). The results indicated a similar yield was

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

• cis-form did not show any decomposition under these conditions (Figure S27C, Supporting Information File 1), unlike when the oF4Azo was grafted onto a pyrrole scaffold [48]. Next, we explored if the inclusion of oF4Azo as monomer surrogate within the PNA sequence could affect its hybridization to a

Ultrafast processes triggered by one- and two-photon excitation of a photochromic and luminescent hydrazone

• Alessandro Iagatti,
• Baihao Shao,
• Alberto Credi,
• Barbara Ventura,
• Ivan Aprahamian and
• Mariangela Di Donato

Beilstein J. Org. Chem. 2019, 15, 2438–2446, doi:10.3762/bjoc.15.236

• decomposition) analysis of the kinetic traces matrix [31]. In this case, although three exponential functions could be sufficient to satisfactory fit the data, the addition of a fourth long living component, associated to a small spectral offset remaining on the long timescale, substantially improved the fit

• analysis [30]. The number of kinetic components has been estimated by performing a preliminary singular values decomposition (SVD) analysis [31], global analysis was performed using the GLOTARAN package (http://glotaran.org) [36], and employing a linear unidirectional “sequential” model. a) The

Targeted photoswitchable imaging of intracellular glutathione by a photochromic glycosheet sensor

• Xianzhi Chai,
• Hai-Hao Han,
• Yi Zang,
• Jia Li,
• Xiao-Peng He,
• Junji Zhang and
• He Tian

Beilstein J. Org. Chem. 2019, 15, 2380–2389, doi:10.3762/bjoc.15.230

• as biosensing/imaging, bioactivity modulation, drug delivery, etc [23][24]. In our system, the Glyco-DTE@MnO2 hybrid sensor undergoes decomposition when encountering the overexpressed intracellular GSH in HepG2 cell lines, following the recovery of the photoswitchable fluorescence signal regulated by

• in PBS buffer. As shown in Figure 3B, the emission of Glyco-DTE was restored to ca. 90% (ΦF = 0.256, Table S1 in Supporting Information File 1) with the addition of 1.5 mM GSH. The recovery of emission can be attributed to the reduction of MnO2 to Mn2+ [21], leading to the decomposition of MnO2

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

• details of the reaction dynamics, we performed global analyses with singular value decomposition (SVD) with the Glotaran program (http://glotaran.org) [43]. We tentatively used the three-state sequential kinetic model for benzil (Equation 1) and the five-state sequential kinetic model for Benzil-PIC

Thermal stability of N-heterocycle-stabilized iodanes – a systematic investigation

• Andreas Boelke,
• Yulia A. Vlasenko,
• Mekhman S. Yusubov,
• Boris J. Nachtsheim and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2019, 15, 2311–2318, doi:10.3762/bjoc.15.223

• (TGA) and differential scanning calorimetry (DSC) is investigated. Peak decomposition temperatures (Tpeak) were observed within a wide range between 120 and 270 °C. Decomposition enthalpies (ΔHdec) varied from −29.81 to 141.13 kJ/mol. A direct comparison between pseudocyclic and cyclic NHIs revealed

• alkyl and aryl radicals through thermogravimetry [16][17]. In 2013 Kumar and co-workers compared the thermal properties of open-chained aryl-λ3-iodanes with their polymer bound derivatives and found an endothermic decomposition behavior [18]. In the same year Haller and co-workers investigated the

• the amide-stabilized derivative ABZ (azidobenziodazolone). They found a remarkable higher thermal stability of the latter compound by DSC analysis indicated by a higher onset temperature and a lower heat release during decomposition [21]. ABZ is a rare example of a nitrogen-stabilized iodane, showing

Synthesis of acremines A, B and F and studies on the bisacremines

• Nils Winter and
• Dirk Trauner

Beilstein J. Org. Chem. 2019, 15, 2271–2276, doi:10.3762/bjoc.15.219

• speculated that this reaction might proceed through ionic intermediates (Scheme 4). To probe this hypothesis, we tried to generate allylic cation 19 by treatment with different acids or under thermal conditions (Table 1). Unfortunately, all conditions led to either decomposition of the starting material or

• enhance the stability of the molecule, and therefore prevent decomposition, by protection of the non-participating alcohols and attempts to generate the allylic cation from a cyclic ketal [10][11][12], aiming for a Gassman-type reaction mechanism, were also unfruitful. While radical cations are known to

• undergo Diels–Alder reactions with electron-rich dienophiles [13][14][15][16][17], treatment of 5 with Fukuzumi’s catalyst [18] under illumination with blue light only led to decomposition of the starting material (Table 1, entry 15). Notably, a photoredox catalyst with a lower oxidation potential could

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

• catalyst, AgF as fluoride source, NMO as oxidant, and DMF as solvent, they achieved the selective mono- or difluorination in high yields (Scheme 34). Notably, pyridine as an additive could prevent the decomposition of an amide substrate in a long-time reaction. Meanwhile, the group of Sanford [79

Cyclopropanation–ring expansion of 3-chloroindoles with α-halodiazoacetates: novel synthesis of 4-quinolone-3-carboxylic acid and norfloxacin

• Sara Peeters,
• Linn Neerbye Berntsen,
• Pål Rongved and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2019, 15, 2156–2160, doi:10.3762/bjoc.15.212

• decomposition of diazo compounds, are particularly versatile intermediates in organic synthesis, as they partake in cyclopropanation and C–H insertion reactions with high levels of selectivity [2]. This transition-metal-catalyzed carbene transfer has emerged as a mild and attractive route to indole

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

Characterization of two new degradation products of atorvastatin calcium formed upon treatment with strong acids

• Jürgen Krauß,
• Monika Klimt,
• Markus Luber,
• Peter Mayer and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2085–2091, doi:10.3762/bjoc.15.206

• stress tests on atorvastatin (and its salts), and an overview has been published by Sirén [5]. Hereby, atorvastatin was found to be sensitive to acidic, oxidative, photochemical and thermal stress. Acidic degradation of atorvastatin was reported to follow first order kinetics, but decomposition products

• were not characterized in this [6] and several other reports, which only determined the downsizing of the atorvastatin peak in HPLC after treatment with acid [7][8][9][10]. The most prominent decomposition product upon acidic treatment, compound 2, results from lactonization of the 3,5

• -dihydroxyheptanoate side chain under moderately acidic conditions (0.1 M HCl) [11][12][13][14]. Shah et al. [15] identified six additional decomposition products upon treatment with 0.1 M HCl at 80 °C for 24 h, among which the dehydrated lactone 3 was dominating, accompanied by minor amounts of products arising from

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

• (THTAA) – a heterocycle involving both >N–H donating and =N– accepting moieties – have been reinvestigated. Unlike previously reported, THTAA is a thermally stable compound that can be re-sublimed at 300–310 °C without decomposition. Controlled introduction of substituents at the nitrogen atoms of THTAA

• unidentified dark brown poorly soluble solid. The crystallized samples of THTAA can be sublimed at about 300 °C at ambient pressure without decomposition affording bright yellow needles in contrast to the observation of decomposition in the original paper [5]. The formation of tetraazaanthracene (TAA, 5) was

• sublimed at about 300 °C without decomposition. Sublimation is required for its complete purification. The crystal structures of 3 and its derivatives exhibit the formation of infinite chains binding molecules in the side-to-side manner even in the case when a substituent is present at one of the nitrogen

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

• auxiliary was perfect, purification of 2 by silica gel chromatography was problematic due to decomposition. No pure product was isolated from crude 2 by chromatography on silica gel. Decomposition occurred to a compound similar to 2, in which the 3-substituent was CH2OH [49]. To overcome this problem, the

Norbornadiene-functionalized triazatriangulenium and trioxatriangulenium platforms

• Roland Löw,
• Talina Rusch,
• Tobias Moje,
• Fynn Röhricht,
• Olaf M. Magnussen and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1815–1821, doi:10.3762/bjoc.15.175

• decomposition, which is a necessary precondition for ultra-high vacuum STM investigations. The 3-bromo-2-cyano-substituted norbornadiene 4 was synthesized as described in the literature (Scheme 1) [10][11][12]. 4 was converted to 5 with trimethylsilylacetylene (72%) in a Sonogashira cross-coupling reaction. The

• absorption band with a maximum at 524 nm is due to the TATA cation generated by decomposition during irradiation with 311 nm. The photostationary states were determined in deuterated oxygen containing deuterated benzene and degassed deuterated benzene by 1H NMR measurements (Figure 3). Norbornadiene 1a

• isomerizes quantitatively to quadricyclane 1b by irradiation with 385 nm. Upon irradiation of 1b under nitrogen with 311 nm, the cycloreversion yields 28% norbornadiene (Table 1). The efficiency of the cycloreversion is higher under air (52%), however, slow decomposition was observed (cleavage of the TATA

Metal-free mechanochemical oxidations in Ertalyte^® jars

• Andrea Porcheddu,
• Francesco Delogu,
• Lidia De Luca,
• Claudia Fattuoni and
• Evelina Colacino

Beilstein J. Org. Chem. 2019, 15, 1786–1794, doi:10.3762/bjoc.15.172

• , especially in redox processes conducted in no-metal reactors, could prevent excessive heating of the jar, avoid the decomposition of starting materials and therefore, limit the formation of byproducts [40]. Following our interest in mechanochemistry and the design of new cost-effective oxidation procedures

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

• András György Németh,
• György Miklós Keserű and
• Péter Ábrányi-Balogh

Beilstein J. Org. Chem. 2019, 15, 1523–1533, doi:10.3762/bjoc.15.155

• -diimidazole or di-2-pyridyl thionocarbonate [57][58]. Decomposition of dithiocarbamate salts or thiocarbamates with various reagents offers a good alternative [59][60][61][62] as well, however, this approach first requires the synthesis of the appropriate precursor. Nitrile oxides react with thiourea to

• unfavorable, providing the thiocarbamate in 67%, 29%, 12% and 30% yields, respectively (Table 1, entries 10, 11, 12, and 14). Notably, in the lack of inert atmosphere, the yield decreased to 72%, and unidentified byproducts were detected that might be explained with the decomposition or side reactions of the

Anomeric sugar boronic acid analogues as potential agents for boron neutron capture therapy

• Daniela Imperio,
• Erika Del Grosso,
• Silvia Fallarini,
• Grazia Lombardi and
• Luigi Panza

Beilstein J. Org. Chem. 2019, 15, 1355–1359, doi:10.3762/bjoc.15.135

• the desired product 7 by the simple treatment of 6 with an excess of borane-THF complex (5 molar equiv) followed by quenching with water, while in the same conditions compound 5 again gave extensive decomposition. These conditions allowed the isolation of the cyclic anomeric boron analogue 7 in

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

• –300 °C, whereas neat PFA is still stable at that temperature. This first degradation can be attributed to the decomposition of the peptidic skeleton, while at around 300 °C the decomposition of the polymeric lattice matrix starts, also of PFA. This analysis further demonstrates the incorporation of

Alkylation of lithiated dimethyl tartrate acetonide with unactivated alkyl halides and application to an asymmetric synthesis of the 2,8-dioxabicyclo[3.2.1]octane core of squalestatins/zaragozic acids

• Herman O. Sintim,
• Hamad H. Al Mamari,
• Hasanain A. A. Almohseni,
• Younes Fegheh-Hassanpour and
• David M. Hodgson

Beilstein J. Org. Chem. 2019, 15, 1194–1202, doi:10.3762/bjoc.15.116

• deprotect the TBDPS ether more slowly than FeCl3, and adjustment of the reaction conditions with AlCl3 (to 2 equiv in CH2Cl2, −78 °C, followed by slow warming to −50 °C) cleanly provided α-ketoester 20 (Scheme 6). α-Ketoesters can be prone to hydrate easily (2D TLC analysis of 20 indicated decomposition

Mechanochemical synthesis of hyper-crosslinked polymers: influences on their pore structure and adsorption behaviour for organic vapors

• Sven Grätz,
• Sebastian Zink,
• Hanna Kraffczyk,
• Marcus Rose and
• Lars Borchardt

Beilstein J. Org. Chem. 2019, 15, 1154–1161, doi:10.3762/bjoc.15.112

• protocol the polymer obtained through this mechanochemical route is also amorphous as visualized by the XRD (X-ray diffraction) patters recorded (Supporting Information File 1, Figure S1) [43]. Furthermore, NG-HCP similarly shows a high thermal stability with a decomposition onset in air (Supporting

Design of a double-decker coordination cage revisited to make new cages and exemplify ligand isomerism

• Sagarika Samantray,
• Sreenivasulu Bandi and
• Dillip K. Chand

Beilstein J. Org. Chem. 2019, 15, 1129–1140, doi:10.3762/bjoc.15.109

• was found to be unstable and it decomposed within a few hours. Thus the 1H NMR and ESIMS spectrum of 5a were recorded from freshly prepared samples. The complexes 4a, 6a and 7a are quite stable and no decomposition was observed. Detailed characterization data of 4a–7a form a variety of NMR techniques

• to form (e.g., from 4a and L1) and prone to decomposition. As far as trinuclear complex formation is concerned the central pyridine ring of L1 is in a relatively favorable situation, thus the complex 4a could form and 3a was a kinetic product. Conclusion A set of mononuclear and trinuclear complexes

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

• temperature range of 25–650 °C are depicted in Figure S7 (Supporting Information File 1). From the TG/DTG curves, the thermal decomposition temperatures of the PCL/CB[7] nanofibers are higher than that of CB[7] alone, demonstrating a better thermal stability of the PCL/CB[7] nanofiber composites. Methylene

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• stabilities by exhibiting a decomposition temperature up to 320 °C. In 2013, Severin and co-workers reported the mechanochemical synthesis of large macrocycles with borasiloxane and imine links using a ball mill (Figure 12). In a polycondensation reaction using diamines, 4-formylbenzeneboronic acid and t