Annulation of 1H-pyrrole-2,3-diones by thioacetamide: an approach to 5-azaisatins

• Aleksandr I. Kobelev,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 364–370, doi:10.3762/bjoc.15.32

• . To confirm the proposed pathway and optimize the reaction conditions, we carried out a series of experiments using the PBT 2a. First, the solvent effect was checked (Table 1). We found that the solvent played a crucial role, and the best yields were observed in hygroscopic polar solvents (Table 1

Catalysis of linear alkene metathesis by Grubbs-type ruthenium alkylidene complexes containing hemilabile α,α-diphenyl-(monosubstituted-pyridin-2-yl)methanolato ligands

• Tegene T. Tole,
• Johan H. L. Jordaan and
• Hermanus C. M. Vosloo

Beilstein J. Org. Chem. 2019, 15, 194–209, doi:10.3762/bjoc.15.19

• was used as solvent with an 8.9% increase at 420 min. This affected the other performance indicators, i.e., PMPs, S, TON and TOF; lower values than the neat reactions were obtained. The results suggest that no significant solvent effect appears to exist .However, the increase in SMPs (associated with

A three-armed cryptand with triazine and pyridine units: synthesis, structure and complexation with polycyclic aromatic compounds

• Claudia Lar,
• Adrian Woiczechowski-Pop,
• Attila Bende,
• Ioana Georgeta Grosu,
• Natalia Miklášová,
• Elena Bogdan,
• Niculina Daniela Hădade,
• Anamaria Terec and
• Ion Grosu

Beilstein J. Org. Chem. 2018, 14, 1370–1377, doi:10.3762/bjoc.14.115

• , anthracene and 1,5-dihydroxynaphthalene have been obtained at density functional theory level, using the M11 [42] exchange-correlation functional and the def2-TZVP [43] basis set implemented in the Gaussian 09 program package [44]. In order to take into account the solvent effect induced by the DMSO solvent

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions

• Kendra Leahy Denlinger,
• Lianna Ortiz-Trankina,
• Preston Carr,
• Kingsley Benson,
• Daniel C. Waddell and
• James Mack

Beilstein J. Org. Chem. 2018, 14, 688–696, doi:10.3762/bjoc.14.57

• between the steps. LAG solvent effect on the mechanochemical Wittig reaction. Control reactions to determine the origin of the side product benzyl benzoate. Counter-ion partnerships. Counter-ion partnerships in the solvent-free mechanochemical Wittig reaction. How much 4-nitrobenzyl bromide adds to the

Regioselective decarboxylative addition of malonic acid and its mono(thio)esters to 4-trifluoromethylpyrimidin-2(1H)-ones

• Sergii V. Melnykov,
• Andrii S. Pataman,
• Yurii V. Dmytriv,
• Svitlana V. Shishkina,
• Mykhailo V. Vovk and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2017, 13, 2617–2625, doi:10.3762/bjoc.13.259

• is perfectly feasible with a precise control of the reaction conditions. A remarkable solvent effect has been observed which governs the ratio of the resulting regioisomeric decarboxylated adducts 4 and 5 and allows their preparative selective isolation. This effect may well be attributed to a two

Conformational impact of structural modifications in 2-fluorocyclohexanone

• Francisco A. Martins,
• Josué M. Silla and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2017, 13, 1781–1787, doi:10.3762/bjoc.13.172

• intramolecular forces, as well as the solvent effect, are affected by the different groups (CH2, NH, O and S) attached to these positions. Indeed, diverse conformational behaviors are observed when changing X and Y (Table 1). Nevertheless, it is worth noting that, in general, the axial population increases in

• of the studied compounds, according to the NBO analysis and in spite of some stabilizing electronic delocalization interactions from electron-donor orbitals to antiperiplanar antibonding orbitals. The electronic interactions mentioned above appeared to be sensitive to the solvent effect, since the

Base-promoted isomerization of CF₃-containing allylic alcohols to the corresponding saturated ketones under metal-free conditions

• Yoko Hamada,
• Tomoko Kawasaki-Takasuka and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2017, 13, 1507–1512, doi:10.3762/bjoc.13.149

• proton rather than the one in the propargylic position (ΔΔE of −0.321 and −7.869 kcal/mol for the allylic and propargylic series, respectively). Due to the unacceptable efficiency of K2CO3 and NaOH (Table 2, entries 3–5), the solvent effect was surveyed at the next stage with fixing the base to DBU

• 24.71 kcal/mol after the single point calculation by consideration of the solvent effect of toluene by the conductor-like polarizable continuum model (CPCM). This energy barrier is considered to qualitatively correspond to the requirement of toluene reflux temperature (110–111 °C) for promotion of the

Conformational study of L-methionine and L-cysteine derivatives through quantum chemical calculations and ³J_HH coupling constant analyses

• Weslley G. D. P. Silva,
• Carolyne B. Braga and
• Roberto Rittner

Beilstein J. Org. Chem. 2017, 13, 925–937, doi:10.3762/bjoc.13.94

• conformers of 1 are not very sensitive to the solvent effect. The same conformers were found in isolated phase and in solution for compound 2. Moreover, its four more stable geometries (2-Ib, 2-IIa, 2-IIIa and 2-IVa) represent approximately 80% of the conformational equilibrium (Table 2) in all different

• investigated media. As well as for 1, geometries of 2 do not present significant variations when ε is increased. It also demonstrates that the solvent effect does not affect the conformer populations of 2. To obtain more details about the solvent effect in the conformational isomerism of the studied compounds

• are not very sensitive to solvent effect. When it comes to the study of amino acids and their derivatives, some studies found in the literature explain the conformational stability of amino acids solely by the formation of an intramolecular hydrogen bonding (IHB) [2][8][13]. Thus, to investigate the

The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

• Erika Bálint,
• Ádám Tajti,
• Anna Ádám,
• István Csontos,
• Konstantin Karaghiosoff,
• Mátyás Czugler,
• Péter Ábrányi-Balogh and
• György Keglevich

Beilstein J. Org. Chem. 2017, 13, 76–86, doi:10.3762/bjoc.13.10

• B3LYP/6-31G (d,p) method. In the solvent-free reaction, the dielectric constant of the P reagent was estimated as 78.3553. This value was taken into account as an implicit solvent effect. First, the tautomeric equilibria of dialkyl phosphites and diphenylphosphine oxide were studied (Table 8). It was

Chromium(II)-catalyzed enantioselective arylation of ketones

• Gang Wang,
• Shutao Sun,
• Ying Mao,
• Zhiyu Xie and
• Lei Liu

Beilstein J. Org. Chem. 2016, 12, 2771–2775, doi:10.3762/bjoc.12.275

• substituted oxazoline proved to be the best ligand with a 42% ee. Afterwards, R2 (Table 1, entries 2, 5 and 6) and R3 (Table 1, entries 6–8) substituents were also examined, and L8 bearing a methyl group in both R2 and R3 gave the best enantiocontrol. The solvent effect was then investigated, and 1,2

Highly chemo-, enantio-, and diastereoselective [4 + 2] cycloaddition of 5H-thiazol-4-ones with N-itaconimides

• Shuai Qiu,
• Choon-Hong Tan and
• Zhiyong Jiang

Beilstein J. Org. Chem. 2016, 12, 2293–2297, doi:10.3762/bjoc.12.222

• dipeptide-based tertiary amine for this type of reaction. By modifying the thiourea moiety of III to urea lead us to catalyst DP-UAA IV, which could further increase the enantioselectivity (Table 1, entry 4). Subsequently, we screened the solvent effect with IV as the catalyst (Table 1, entries 5–7), and

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• more amenable to a wider range of groups on nitrogen, though a significant solvent effect was still observed in these cases. The mechanism of the reaction was then probed by performing the redox isomerization reaction on enantioenriched propargyl alcohols. While a significant matched/mismatched effect

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• amines. However, as can be seen from Table 1, the formation of the latter was not observed when ethanol was used as the solvent. To further test the solvent effect on the outcome of the reaction, we repeated the photolysis of azides 1a–f under the optimized conditions but in aqueous dioxane instead of

Synthesis and fluorosolvatochromism of 3-arylnaphtho[1,2-b]quinolizinium derivatives

• Phil M. Pithan,
• David Decker,
• Manlio Sutero Sardo,
• Giampietro Viola and
• Heiko Ihmels

Beilstein J. Org. Chem. 2016, 12, 854–862, doi:10.3762/bjoc.12.84

• , the limited solubility of the derivatives 6b–e did not permit to employ a large series of solvents that is required for such a multiparameter analysis of these compounds. Nevertheless, the separation of the solvents into protic and aprotic solvents reveals at least a general trend of the solvent

• effect on the emission properties of 6e. Namely, the emission maxima shift to lower energy with increasing polarity of the aprotic solvents (Figure 5). This qualitative relationship denotes a larger dipole moment of the molecule in the excited state than in the ground state, as usually observed in donor

Regioselective palladium-catalyzed ring-opening reactions of C1-substituted oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylates

• Michael Edmunds,
• Mohammed Abdul Raheem,
• Rebecca Boutin,
• Katrina Tait and
• William Tam

Beilstein J. Org. Chem. 2016, 12, 239–244, doi:10.3762/bjoc.12.25

• -opening of C1 substituted oxabenzonorbornadiene. Proposed mechanism for the palladium-catalyzed ring-opening reaction of oxanorbornadiene. Optimization of palladium catalyst, Lewis acid additive, and solvent. Effect of aryl iodide substitution on the ring-opening of oxanorbornadiene. Effect of C1

Co-solvation effect on the binding mode of the α-mangostin/β-cyclodextrin inclusion complex

• Chompoonut Rungnim,
• Sarunya Phunpee,
• Manaschai Kunaseth,
• Supawadee Namuangruk,
• Kanin Rungsardthong,
• Thanyada Rungrotmongkol and
• Uracha Ruktanonchai

Beilstein J. Org. Chem. 2015, 11, 2306–2317, doi:10.3762/bjoc.11.251

• /guest/co-solvent ternary complexes. In other studies, the co-solvent has been shown to compete with the drug molecules for the entry into the CD cavity, with the result of lower drug loadings (inclusion of drug molecules) in the system. Besides, the co-solvent effect was found as a factor that control

Copper-mediated synthesis of N-alkenyl-α,β-unsaturated nitrones and their conversion to tri- and tetrasubstituted pyridines

• Dimitra Kontokosta,
• Daniel S. Mueller,
• Dong-Liang Mo,
• Wiktoria H. Pace,
• Rachel A. Simpson and
• Laura L. Anderson

Beilstein J. Org. Chem. 2015, 11, 2097–2104, doi:10.3762/bjoc.11.226

• to the β-position of the conjugated olefin followed by nucleophilic attack of the enamine. Use of a Chan–Lam reaction for the synthesis of tetrahydroquinolines and potential extension to pyridines [8]. Examples of pyridine synthesis from oxime precursors [51][52]. Solvent effect on conversion of N

A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts

• Albert Poater and
• Luigi Cavallo

Beilstein J. Org. Chem. 2015, 11, 1767–1780, doi:10.3762/bjoc.11.192

• isomer plays a key role, especially if taking into account the solvent effect. Therefore, calculations indicate that the preferred reaction pathway is an equilibrium described by steric, electronic, and solvent effects. In spite of the expectation that the hydrogen atom is the less sterically demanding

• ligands [16] and bulky substrates make the bottom reaction pathway more likely surpassing the other effects. Finally the solvent effect helps the stabilization of the side-bound isomer, but at a higher degree for the high sterically demanding complexes. As already stated by Goddard, polar solvents favor

The enantioselective synthesis of (S)-(+)-mianserin and (S)-(+)-epinastine

• Piotr Roszkowski,
• Jan. K. Maurin and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2015, 11, 1509–1513, doi:10.3762/bjoc.11.164

• regardless of the solvent used, with the exception of acetonitrile (Table 1, entries 8–10). In CH3CN this catalyst is inactive and the product was not formed. The solvent effect on the chemical yield was similar to that observed with catalyst 11 (Table 1). Finally, the ruthenium complex 13 modified with

Antioxidant potential of curcumin-related compounds studied by chemiluminescence kinetics, chain-breaking efficiencies, scavenging activity (ORAC) and DFT calculations

• Adriana K. Slavova-Kazakova,
• Silvia E. Angelova,
• Timur L. Veprintsev,
• Petko Denev,
• Davide Fabbri,
• Maria Antonietta Dettori,
• Maria Kratchanova,
• Vladimir V. Naumov,
• Aleksei V. Trofimov,
• Rostislav F. Vasil’ev,
• Giovanna Delogu and
• Vessela D. Kancheva

Beilstein J. Org. Chem. 2015, 11, 1398–1411, doi:10.3762/bjoc.11.151

• the kinetic solvent effect of water is of great importance in this case. Hydrogen bonding can have a profound influence on the activity of phenols as antioxidants. It is generally recognized [28][29][30] that solvent effects and especially the ionization effect of the medium may alter the mechanism of

• dimers in terms of the HAT reaction mechanism. This could be explained by the solvent effect of water, blocking OH groups by H bonds and thus decreasing their antioxidant capacity. Another reason for the similar results obtained for the studied monomers/dimers is the fact that the process is monitored by

Properties of PTFE tape as a semipermeable membrane in fluorous reactions

• Brendon A. Parsons,
• Olivia Lin Smith,
• Myeong Chae and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2015, 11, 980–993, doi:10.3762/bjoc.11.110

• chemically more akin to the adsorbed solvent than its own fluorous structure. From the limited data available, it appears that this solvent effect can be related to the surface tension of the solvent and the polarity of the solvent relative to the reagent. If the surface tension is within the range necessary

Cathodic reductive coupling of methyl cinnamate on boron-doped diamond electrodes and synthesis of new neolignan-type products

• Taiki Kojima,
• Rika Obata,
• Tsuyoshi Saito,
• Yasuaki Einaga and
• Shigeru Nishiyama

Beilstein J. Org. Chem. 2015, 11, 200–203, doi:10.3762/bjoc.11.21

• inseparable mixture of 6 and 7, which were identified by 1H NMR spectroscopy. Subsequent treatment of the mixture with Et3SiH in the presence of BF3·OEt2 finally gave E-8. Conclusion The cathodic reduction of 1a using BDD electrode predominantly gave the dimeric product 2 in 85% yield. A remarkable solvent

• effect of MeCN was observed for this dimerization reaction, while stereoselectivity was unaffected among the conditions tested and the racemic form was predominant over the meso form in all cases. Electrochemically prepared (±)-2 was further converted into E-5 and E-8 as novel unprecedented neolignan

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• resolution of (±)-3 by using both Novozym 435 and Lipozyme TL IM preparations in the next optimization stages. Solvent effect on kinetic resolution of (±)-3 The next stage of enzymatic analytical scale studies was designed to find the most suitable co-solvent system for the enantioselective O-acylation of

Influence of cyclodextrin on the UCST- and LCST-behavior of poly(2-methacrylamido-caprolactam)-co-(N,N-dimethylacrylamide)

• Alexander Burkhart and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 1951–1958, doi:10.3762/bjoc.10.203

• solvent effect, α-D(+)-glucose was added to copolymer 6a in an equimolar amount to the caprolactam groups. As expected, turbidity measurements indicate, that there is no significant increase of the TC. Furthermore, it was found that the copolymer 6a is completely soluble in methanol. However, in less

An experimental and theoretical NMR study of NH-benzimidazoles in solution and in the solid state: proton transfer and tautomerism

• Carla I. Nieto,
• Pilar Cabildo,
• M. Ángeles García,
• Rosa M. Claramunt,
• Ibon Alkorta and
• José Elguero

Beilstein J. Org. Chem. 2014, 10, 1620–1629, doi:10.3762/bjoc.10.168

• calculations including DMSO solvent effect (compare eqs. 9 and 10) and also better with trimer B (in turn, slightly better than with trimer A, compare intercept and slopes of eqs. 12 and 13) than with the monomer (eq. 11). iii) Concerning 15N NMR (eqs. 14–21), the R2 values are lower than with 13C NMR. Both