Solid-phase-supported synthesis of morpholinoglycine oligonucleotide mimics

• Tatyana V. Abramova,
• Sergey S. Belov,
• Yulia V. Tarasenko and
• Vladimir N. Silnikov

Beilstein J. Org. Chem. 2014, 10, 1151–1158, doi:10.3762/bjoc.10.115

• positively charged centers in oligonucleotide analogues results in increased water solubility and higher thermal stability of complementary duplexes of such oligonucleotide mimics with nucleic acids [14][15]. Some conformationally restricted protonated PNA or pyrrolidine oligonucleotide mimics exhibit

• dependence of the thermal stability of complementary complexes formed by the MorGly oligomers on the heterocyclic base composition (uracil or adenine) of the modified chain. It was shown while studying their tandem complexes that the impact of cooperative interactions at oligomer junctions on the thermal

• stability was higher for modified oligomers than for native oligodeoxyriboadenylates. This result may indicate that the contribution of nucleobase stacking to the thermal stability of complementary complexes is more important for the oligonucleotide mimics than for native oligonucleotides. The substitution

The influence of intraannular templates on the liquid crystallinity of shape-persistent macrocycles

• Joscha Vollmeyer,
• Ute Baumeister and
• Sigurd Höger

Beilstein J. Org. Chem. 2014, 10, 910–920, doi:10.3762/bjoc.10.89

• substituents influence the thermal stability of the gel. As pointed out before, the ring interior can also have a dramatic effect on the mesophase stability of thermotropic liquid crystalline shape-persistent macrocycles [40][43][44][45]. However, more detailed studies on that issue are still scarcely found in

N-Alkylated dinitrones from isosorbide as cross-linkers for unsaturated bio-based polyesters

• Oliver Goerz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 902–909, doi:10.3762/bjoc.10.88

• . Efforts have also been undertaken to employ nitrones in the realm of polymer chemistry. For instance, our former reports describe the cycloaddition of bis(N-methylnitrone)s and bis(N-phenylmaleimide)s , which yielded linear polymers bearing isoxazolidine units with high thermal stability [6]. The

Thermodynamically stable [4 + 2] cycloadducts of lanthanum-encapsulated endohedral metallofullerenes

• Yuta Takano,
• Yuki Nagashima,
• M. Ángeles Herranz,
• Nazario Martín and
• Takeshi Akasaka

Beilstein J. Org. Chem. 2014, 10, 714–721, doi:10.3762/bjoc.10.65

• demonstrated the boat-to-boat inversions of the addend. In addition, 5b revealed remarkable thermal stability in comparison with the reported [4 + 2] cycloadduct of pentamethylcyclopentadiene and La@C82 (6). These findings demonstrate the utility of sultines to afford thermodynamically stable endohedral

• , respectively, was achieved by the selective thermal decomposition of unstable isomers. The thermal stability of 5b was also evaluated in comparison with 6, and 5b shows remarkable thermal stability. The molecular structures of the resulting compounds were characterized by spectroscopic analyses. Dynamic 1H NMR

Total synthesis and cytotoxicity of the marine natural product malevamide D and a photoreactive analog

• Werner Telle,
• Gerhard Kelter,
• Heinz-Herbert Fiebig,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2014, 10, 316–322, doi:10.3762/bjoc.10.29

• ) and acidic deprotection afforded diazirine diol 25. Figure 2 shows the DSC (differential scanning calorimetry) profile of 25, which melts at 54 °C and starts to decompose above 80 °C, indicating sufficient thermal stability for biological studies. Monosilylation of the primary hydroxy group of 25

Cyclic phosphonium ionic liquids

• Sharon I. Lall-Ramnarine,
• Joshua A. Mukhlall,
• James F. Wishart,
• Robert R. Engel,
• Alicia R. Romeo,
• Masao Gohdo,
• Sharon Ramati,
• Marc Berman and
• Sophia N. Suarez

Beilstein J. Org. Chem. 2014, 10, 271–275, doi:10.3762/bjoc.10.22

• synthesize ILs with improved properties (such as viscosity, thermal stability, melting point, etc.) to expand their applications into larger scale processes in diverse areas. Along that vein, phosphonium ILs have been observed to have favorable characteristics, including lower costs [2][3][4][5][6], lower

• viscosity (by ~50%) [7][8][9][10][11], greater thermal stability (by ~100 °C) [10][11][12], and wider electrochemical windows compared to their ammonium congeners. The family of ILs bearing cyclic cations (pyrrolidinium, piperidinium, and azepanium) [13][14] have been shown to have better transport and

• cations have greater thermal stability than the ammonium ones. One trend observed for both cation types is that the ILs with five-membered rings have greater thermal stability than those with six-membered rings. Further work will be required to determine if the observed TGA behaviors are due to actual

Synthesis, characterization and initial evaluation of 5-nitro-1-(trifluoromethyl)-3H-1λ³,2-benziodaoxol-3-one

• Nico Santschi,
• Roman C. Sarott,
• Elisabeth Otth,
• Reinhard Kissner and
• Antonio Togni

Beilstein J. Org. Chem. 2014, 10, 1–6, doi:10.3762/bjoc.10.1

• . Consequently in light of these results, DSC measurements of 2 and 3 were carried out in order to assess the thermal stability of the new derivative. These measurements were performed in punctured Al2O3 pans with a heating rate of 10 K/min. For reagent 2, a decomposition energy of 138 kJ/mol (438 J/g, slightly

• lability of 3 was noted such that it decayed almost one order of magnitude faster than 2 under similar conditions. Therefore, the incorporation of an electron-withdrawing group into the reagent scaffold leads to an enhanced thermal stability that is paralleled by increased lability of the I–CF3 bond under

Charge-transfer interaction mediated organogels from 18β-glycyrrhetinic acid appended pyrene

• Jun Hu,
• Jindan Wu,
• Qian Wang and
• Yong Ju

Beilstein J. Org. Chem. 2013, 9, 2877–2885, doi:10.3762/bjoc.9.324

• in the formation of CT gels is demonstrated through the formation of gels in a variety of solvents. Thermal stability, stoichiometry, scanning electron microscopy (SEM), optical micrographs, and circular dichroism (CD) are performed on these CT gels to investigate their thermal and assembly

• observation suggested the presence of a CT complex in the gel system. Thermal stability Sol to gel transition temperature (Tgel) was measured as a function of the total concentration of the 1:1 (molar ratio) donor–acceptor mixture. These were done by inverted test tube experiments after gels were stabilized

• in sealed test tubes for 1–2 h [15][48][49][50]. It was observed that the thermal stability of these CT gels based on 3 and 4 increased with an increase in the total concentration (Figure 2), no matter in what kind of solvent. Based on the Tgel values at different concentrations, the thermodynamic

Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones – First evidence for the 1,3-oxathiole–thiocarbonyl ylide interconversion

• Valerij A. Nikolaev,
• Alexey V. Ivanov,
• Ludmila L. Rodina and
• Grzegorz Mlostoń

Beilstein J. Org. Chem. 2013, 9, 2751–2761, doi:10.3762/bjoc.9.309

• 3b was two times lower (Table 1, entry 2). Increasing the temperature to 80 °C slightly speeded up the process. However, due to the relatively low thermal stability of diazodiketone 2b [7][8][18], side reactions resulting in the formation of oxathiinone 4b (17%) and tetrasubstituted olefin 5b (11

• additional signals could be observed. To clarify the possibility of a thermal decomposition of the diazodicarbonyl compounds and the alternative ‘carbene pathway’ (C), the thermal stability of a series of diazo compounds 2 was examined [7][8][17]. The obtained results allow us to conclude that at room

Stereoselectively fluorinated N-heterocycles: a brief survey

• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2013, 9, 2696–2708, doi:10.3762/bjoc.9.306

• -exo ring pucker of 12 was demonstrated in spectacular fashion: Raines and co-workers showed that the thermal stability of collagen was increased when 12 was incorporated in place of collagen’s naturally-present (4R)-hydroxyproline residues [25]. This hyperconjugation effect has also been exploited in

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• trifluoromethylations and the recent results of the Cu-catalyzed reaction described above, that of difluoromethylation has been more slowly developed. This is probably due to the lack of thermal stability of CuCHF2 [42]. To the best of our knowledge, the direct cross-coupling of CuCHF2 with aromatic halides has not

Biosynthesis of rare hexoses using microorganisms and related enzymes

• Zijie Li,
• Yahui Gao,
• Hideki Nakanishi,
• Xiaodong Gao and
• Li Cai

Beilstein J. Org. Chem. 2013, 9, 2434–2445, doi:10.3762/bjoc.9.281

• extensively studied, particularly from D-galactose by L-arabinose isomerase (AI, EC 5.3.1.4) (Scheme 1) [14][15][16][17][18][19][20]. As the interconversion equilibrium between D-galactose and D-tagatose shifts toward D-tagatose at higher temperatures, biocatalysts with greater thermal stability are preferred

Flow synthesis of phenylserine using threonine aldolase immobilized on Eupergit support

• Jagdish D. Tibhe,
• Hui Fu,
• Timothy Noël,
• Qi Wang,
• Jan Meuldijk and
• Volker Hessel

Beilstein J. Org. Chem. 2013, 9, 2168–2179, doi:10.3762/bjoc.9.254

• enzyme. This multipoint attachment provides enhanced conformational stability, which translates to long term operational stability. Fu et al. have already investigated the thermal stability of TA on different supports [48] and found that the enzyme stability increases after immobilization on Eupergit

• support. In continuation of our previous work [48], this paper includes further investigation of the thermal stability of TA on Eupergit by a so-called direct and indirect method. Also, a flow synthesis of Eupergit-immobilized TA in a packed bed microreactor was established and compared to the use of free

• demonstrate a high activity to those reported in the literature. There, only 52.4% enzyme retention and activity retention of 20.7% were achieved while for the indirect method 37% enzyme loading with 31% of activity retention was observed [49]. Comparison of thermal stability of TA immobilized by two

Sequential Diels–Alder/[3,3]-sigmatropic rearrangement reactions of β-nitrostyrene with 3-methyl-1,3-pentadiene

• Peter A. Wade,
• Alma Pipic,
• Matthias Zeller and
• Panagiota Tsetsakos

Beilstein J. Org. Chem. 2013, 9, 2137–2146, doi:10.3762/bjoc.9.251

• well involve zwitterion 15 as the intermediate since nitronic esters 5 and 6 equilibrate under these conditions presumably through 15. The thermal stability of nitronic esters 4–7 appears to be roughly similar to nitronic esters 2 and 3: all have half-life’s greater than one hour at 100 °C with the

Synthesis of enantiomerically pure (2S,3S)-5,5,5-trifluoroisoleucine and (2R,3S)-5,5,5-trifluoro-allo-isoleucine

• Holger Erdbrink,
• Elisabeth K. Nyakatura,
• Susanne Huhmann,
• Ulla I. M. Gerling,
• Dieter Lentz,
• Beate Koksch and
• Constantin Czekelius

Beilstein J. Org. Chem. 2013, 9, 2009–2014, doi:10.3762/bjoc.9.236

• CF3 resulted in an approximately eight-fold higher thermal stability of the respective GCN4 analogue than the replacement of the γ-CH3 group of Val by CF3 [12]. This finding was explained by the substantial loss of side-chain entropy of Val due to steric restriction between the significantly larger γ

Cyclization of substitued 2-(2-fluorophenylazo)azines to azino[1,2-c]benzo[d][1,2,4]triazinium derivatives

• Aleksandra Jankowiak,
• Emilia Obijalska and
• Piotr Kaszynski

Beilstein J. Org. Chem. 2013, 9, 1873–1880, doi:10.3762/bjoc.9.219

• ]. Interestingly, the trifluoro derivative 4d had exceptionally limited thermal stability: After heating at 60 °C in CDCl3 it was converted to another species also containing the picoline fragment, according to the 1H NMR analysis. The new compound did not undergo photocyclization and was not analyzed further

Self-assembly of 2,3-dihydroxycholestane steroids into supramolecular organogels as a soft template for the in-situ generation of silicate nanomaterials

• Valeria C. Edelsztein,
• Andrea S. Mac Cormack,
• Matías Ciarlantini and
• Pablo H. Di Chenna

Beilstein J. Org. Chem. 2013, 9, 1826–1836, doi:10.3762/bjoc.9.213

• scope and thermal stability To assess the scope of the gelation ability of steroids 1–4 in a simple way, the test tube method was first used with 28 selected organic solvents ranging from hydrocarbons to alcohols (Table 1, entries 1–28). While steroids 2–4 were unable to gelate any of these solvents

• on solubility seems to be more suitable for solvent–gelation analysis. All gels were stable, thermoreversible and non-thixotropic. Gels from hydrocarbons were turbid, depending on the concentration of gelator, indicating a low solubility. To estimate the relationship between thermal stability

Thermochemistry and photochemistry of spiroketals derived from indan-2-one: Stepwise processes versus coarctate fragmentations

• Götz Bucher,
• Gernot Heitmann and
• Rainer Herges

Beilstein J. Org. Chem. 2013, 9, 1668–1676, doi:10.3762/bjoc.9.191

• . calcd for C12H14O2: C, 75.8; H, 7.4; found: C, 75.3; H, 7.2. Indan-2-one cis-2-butene-1,4-diol ketal (3) was prepared analogously. Due to the limited thermal stability of 3, benzene had to be used as solvent, and the product could not be distilled. Instead, a sample of the solid dark brown crude product

A³-Coupling catalyzed by robust Au nanoparticles covalently bonded to HS-functionalized cellulose nanocrystalline films

• Jian-Lin Huang,
• Derek G. Gray and
• Chao-Jun Li

Beilstein J. Org. Chem. 2013, 9, 1388–1396, doi:10.3762/bjoc.9.155

• the binding energy around 163.5 in the S2p level. Thermogravimetric analysis (Figure 3) showed that the deposition of AuNPs onto CNC apparently enhanced the thermal stability of the Au@HS-CNC (4.4 mol %) films, which might be due to a composite of the saline reagent (3-mercaptopropyltrimethoxysilane

Linkage of α-cyclodextrin-terminated poly(dimethylsiloxanes) by inclusion of quasi bifunctional ferrocene

• Helmut Ritter,
• Berit Knudsen and
• Valerij Durnev

Beilstein J. Org. Chem. 2013, 9, 1278–1284, doi:10.3762/bjoc.9.144

• macrocycles. The size of the ferrocene molecule is too large to penetrate completely into the α-CD cavity. Only a single cyclopentadienyl ring of the ferrocene is included. The binding mode, thermal stability, formation constants, and dielectric properties [7] of this inclusion complex were also investigated

Incorporation of perfluorohexyl-functionalised thiophenes into oligofluorene-truxenes: synthesis and physical properties

• Neil Thomson,
• Alexander L. Kanibolotsky,
• Joseph Cameron,
• Tell Tuttle,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2013, 9, 1243–1251, doi:10.3762/bjoc.9.141

• electrochemistry and stability, as well as the improved chemical resistance and thermal stability that replacing alkyl hydrogen atoms with fluorine atoms affords [13]. Our group has previously published work on oligofluorene-functionalised truxenes [14], and it was in our interest to observe changes in the optical

3D-printed devices for continuous-flow organic chemistry

• Vincenza Dragone,
• Victor Sans,
• Mali H. Rosnes,
• Philip J. Kitson and
• Leroy Cronin

Beilstein J. Org. Chem. 2013, 9, 951–959, doi:10.3762/bjoc.9.109

• single-step as well as multistep reactions in flow. The chemical and thermal stability of PP makes this generation of custom built flow reactors suitable for the investigation of more complex chemistry. Therefore the next step will be to design and print reactionware devices tailored to selected

New core-pyrene π structure organophotocatalysts usable as highly efficient photoinitiators

• Sofia Telitel,
• Frédéric Dumur,
• Thomas Faury,
• Bernadette Graff,
• Mohamad-Ali Tehfe,
• Didier Gigmes,
• Jean-Pierre Fouassier and
• Jacques Lalevée

Beilstein J. Org. Chem. 2013, 9, 877–890, doi:10.3762/bjoc.9.101

• the cationic polymerization of the epoxide (r11 in Scheme 5). For the other Co_Py, a good thermal stability is found. This dual behavior of some Co_Pys, which are able to initiate both a thermal and a photochemical cationic polymerization, can be very useful to initiate the polymerization in the

Amino-substituted diazocines as pincer-type photochromic switches

• Hanno Sell,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2013, 9, 1–7, doi:10.3762/bjoc.9.1

• the cis isomer is quantitative within the error limits of 1H NMR and UV–vis spectroscopy (Figure 4). Thermal stability of the trans isomers Amino and alkylamino substituents in para position to the azo group reduce the lifetime of the cis states of azobenzenes [15][16]. A dramatically shortened half

Polysiloxane ionic liquids as good solvents for β-cyclodextrin-polydimethylsiloxane polyrotaxane structures

• Narcisa Marangoci,
• Rodinel Ardeleanu,
• Laura Ursu,
• Constanta Ibanescu,
• Maricel Danu,
• Mariana Pinteala and
• Bogdan C. Simionescu

Beilstein J. Org. Chem. 2012, 8, 1610–1618, doi:10.3762/bjoc.8.184

• chemical and nonchemical applications due to their low melting points, nonvolatile and noncorrosive properties at room temperature. They possess good conductivities [1][2] and often they present a good thermal stability up to 400 °C [1][3]. The potential applications of ILs made them the subject of a