Ligand effects, solvent cooperation, and large kinetic solvent deuterium isotope effects in gold(I)-catalyzed intramolecular alkene hydroamination

• Ruichen Lan,
• Brock Yager,
• Yoonsun Jee,
• Cynthia S. Day and
• Amanda C. Jones

Beilstein J. Org. Chem. 2024, 20, 479–496, doi:10.3762/bjoc.20.43

• both within the context of a classic gold π-activation/protodeauration mechanism and a general acid-catalyzed mechanism without intermediate gold alkyls. Keywords: alkene hydroamination; general acid catalysis; gold catalysis; isotope effect; phosphine ligand effect; solvent effect; Introduction

• correlation of faster rate with more electron-withdrawing ligand. Experiments with other substrates display consistent results (further discussion below, Table 6, catalyst 4a reacts faster than 4c in the reaction of carbamate 1b → 3b). Solvent effect For a screen of solvent effect on the rate of 1a

• gold alkyl was not detected, even under these conditions where an isotope effect is observed or the solvent effect significantly slows the reaction. It is possible that incorporation of deuterated solvent is shifting the mechanism toward rate determining protodeauration, but this does not correspond to

Enhanced host–guest interaction between [10]cycloparaphenylene ([10]CPP) and [5]CPP by cationic charges

• Eiichi Kayahara,
• Yoshiyuki Mizuhata and
• Shigeru Yamago

Beilstein J. Org. Chem. 2024, 20, 436–444, doi:10.3762/bjoc.20.38

• . However, the low solubility and stability of the dication in polar solvents prevented confirmation of the solvent effect. To clarify the additional interaction in the complex, the electrochemical analysis of the [10]CPP⊃[5]CPP2+[B(C6F5)4–]2 was examined by using cyclic voltammetry, which was performed in

• present in solution when the solvent effect is negligible. Formation of complex 1 in the gas phase was highly exothermic with ΔG = −222 kJ mol−1 at 298.15 K and 1.00 atm, and this value is about two times higher than that of the complex formation of neutral [10]CPP⊃[5]CPP (ΔG = −114 kJ mol−1). Therefore

Chiral phosphoric acid-catalyzed transfer hydrogenation of 3,3-difluoro-3H-indoles

• Yumei Wang,
• Guangzhu Wang,
• Yanping Zhu and
• Kaiwu Dong

Beilstein J. Org. Chem. 2024, 20, 205–211, doi:10.3762/bjoc.20.20

• achieving high selectivity. Also, an obvious solvent effect on the enantioselectivity was observed (Table 1, entries 7–10). Very low ee values of product 2a were detected when the reaction was performed in DMSO or MeOH (Table 1, entries 7 and 8), while using DCE or toluene as the solvent the

A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen

• Gyula Dargó,
• Dóra Erdélyi,
• Balázs Molnár,
• Péter Kisszékelyi,
• Zsófia Garádi and
• József Kupai

Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133

• chosen as a precipitating solvent for the catalyst recycling. To investigate the solvent effect, the stereoselective Michael addition reaction was carried out in those solvents that dissolved the catalyst and from which the catalyst was successfully precipitated by adding methanol. Furthermore, a

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• control experiment, SO2F2 is essential for the reaction to proceed (Table 1, entry 2). Encouraged by the preliminary result, we then screened a large variety of conditions as shown in Table 1 in order to improve the efficiency of the transformation. The investigation of the solvent effect revealed that in

Synthesis of N-phenyl- and N-thiazolyl-1H-indazoles by copper-catalyzed intramolecular N-arylation of ortho-chlorinated arylhydrazones

• Yara Cristina Marchioro Barbosa,
• Guilherme Caneppele Paveglio,
• Claudio Martin Pereira de Pereira,
• Sidnei Moura,
• Cristiane Storck Schwalm,
• Gleison Antonio Casagrande and
• Lucas Pizzuti

Beilstein J. Org. Chem. 2022, 18, 1079–1087, doi:10.3762/bjoc.18.110

• 120 °C, which gave the product 2a in 32% yield. Increasing the time to 12 h led to a better yield of 40% (Table 1, entry 2). The best yield (60%) was reached after 24 h (Table 1, entry 3). The reduction of the temperature to 100 °C drastically decreased the yield of 2a (Table 1, entry 4). The solvent

• effect on the reaction yield was evaluated employing other aprotic solvents, but no improvement was observed compared to when DMF was used (Table 1, entries 5–7). When the reaction was carried out in NMP (N-methyl-2-pyrrolidone), the 1H NMR spectrum of the crude mixture obtained after extraction did not

Syntheses of novel pyridine-based low-molecular-weight luminogens possessing aggregation-induced emission enhancement (AIEE) properties

• Masayori Hagimori,
• Tatsusada Yoshida,
• Yasuhisa Nishimura,
• Yukiko Ogawa and
• Keitaro Tanaka

Beilstein J. Org. Chem. 2022, 18, 580–587, doi:10.3762/bjoc.18.60

• 464 to 468 nm. From calculations, a smaller solvent effect is seen in the Exmaxcalc values for compound 4a (484–488 nm) and 4e (404–407 nm), whereas the Exmaxobs were found at 476 nm in ethanol and 413 nm in water for 4a and at 378 nm in ethanol and 415 nm in water for compound 4e, respectively. This

DABCO-promoted photocatalytic C–H functionalization of aldehydes

• Bruno Maia da Silva Santos,
• Mariana dos Santos Dupim,
• Cauê Paula de Souza,
• Thiago Messias Cardozo and
• Fernanda Gadini Finelli

Beilstein J. Org. Chem. 2021, 17, 2959–2967, doi:10.3762/bjoc.17.205

• the reaction step with 1 in gas phase and in 1,4-dioxane. The HAT reaction step catalyzed with quinuclidine is exergonic (−8.0 kcal·mol−1), while the reaction step involving DABCO is endergonic (+6.8 kcal·mol−1), in agreement with what would be expected from BDE and BDFE analyses. The solvent effect

•  3. The energy profiles also show that when the solvent effect is included (blue lines), the RC and RP structures become less stable relative to the isolated reactants and products. As a result, for the DABCO cation radical, the reaction barrier relative to the RC structure is 14.07 kcal·mol−1, lower

Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

• Ilya A. P. Jourjine,
• Lukas Zeisel,
• Jürgen Krauß and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2668–2679, doi:10.3762/bjoc.17.181

• gives only a low cyclization yield (Table 1, entry 12). It is unclear, if water is directly involved with this mechanism, but studies indicate that water may lower the activation barrier for the radical cyclization owing to its solvent effect, as has been previously reported for the radical synthesis of

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

• Robin Klintworth,
• Garreth L. Morgans,
• Stefania M. Scalzullo,
• Charles B. de Koning,
• Willem A. L. van Otterlo and
• Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

• simply a thermally induced reaction, and supporting our premise that a unique protic solvent effect is crucial for facilitating this specific cyclization process. We extended the successful reaction to the 4-methoxyphenyl- and 4-nitrophenylenaminones 25b and 25c, which afforded tetrahydroindolizines 26b

A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids

• Li Liu,
• Yue Li,
• Tiao Huang,
• Dulin Kong and
• Mingshu Wu

Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150

• ) under solvent-free and catalyst-free conditions at room temperature (Table 1, entry 1). To our delight, the desired product 3a was obtained in 19% yield. To further improve the yield, we firstly probed the solvent effect using methanol, THF, toluene, ClCH2CH2Cl, 1,4-dioxane, chloroform, dichloromethane

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

• Anka Utama Putra,
• Deniz Çakmaz,
• Nurgül Seferoğlu,
• Alberto Barsella and
• Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

• all dyes were evaluated by thermogravimetric analysis (TGA). The TGA data showed that all dyes were thermally stable up to 250 °C. Keywords: DFT calculations; NLO; pH sensitive dyes; Schiff base; solvent effect; styryl dyes; Introduction Push-pull organic molecules are a class of organic dyes

• and 8 > 9 > 10 > 11 > 12 in DMSO, which was consistent with the experimental data (Table 1 and Table S1 in Supporting Information File 1). A solvent effect on the absorption spectra was observed for compound 4 resulting in a bathochromic shift of about 22 nm from PhMe to DMSO, whereas there was only a

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

• ] (Figure 2). Optimization and frequency calculation have been accomplished using the B3LYP/6-31+G (d,p) method [20][21][22], followed by single point energy calculation with the B3LYP/6-311++G (3df,3pd) method [23][24], considering the solvent effect of DCM with the IEFPCM implicit solvent model [25] in

• interconversion of these conformers is slow in the NMR time-scale. Although the NMR spectra have been measured in CDCl3, we are convinced that the conformations observed in CDCl3 are in good accordance with the ones computed considering the implicit solvent effect of DCM. Based on the structural similarity, the

• UV detector, under the conditions described below for compound 23b. The DFT level computations at the B3LYP/6-31+G (d,p) level of theory were performed considering the solvent effect of DCM using the IEFPCM solvent model with the Gaussian 09 program package. The geometries of the molecules were

Suzuki–Miyaura cross coupling is not an informative reaction to demonstrate the performance of new solvents

• James Sherwood

Beilstein J. Org. Chem. 2020, 16, 1001–1005, doi:10.3762/bjoc.16.89

• across the three case studies typify the lack of an obvious solvent effect. In one instance DMI is the best performing solvent (case study 1), then the worst aside from the reactive Cyrene™ (case study 2), and then somewhere in between (case study 3). To demonstrate that not even case study 3 is robust

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

• considered. To consider the solvent effect, the polarizable continuum model (PCM) for methanol was applied. ECD spectra were obtained using SpecDis 1.71 [57][58] and averaged using Boltzmann factors evaluated at 293 K. In the calculated/experimental ECD comparison, wavelength shifts and intensity scaling

Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red

• Aydan Yadigarli,
• Qimeng Song,
• Sergey I. Druzhinin and
• Holger Schönherr

Beilstein J. Org. Chem. 2019, 15, 2552–2562, doi:10.3762/bjoc.15.248

• decreases in the series of the spin-coating solvents dichloromethane, chloroform and 1,2-dichloroethane. The absolute value of the red drift rate dνf/dλe gradually grows up in the same series. This cast solvent effect of 200 and 130 cm−1 with low and high PMMA molar mass is more pronounced than 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

• calculations. As for the solvent effect, polarizable continuum model (PCM) [36] was employed for THF. X-ray crystallographic analysis for crystal of 1o was carried out at BL40XU beamline of SPring-8. Si(111) channel cut monochromator was used and the wavelength and the size of X-ray beam were 0.81106 Å and 150

Tautomerism as primary signaling mechanism in metal sensing: the case of amide group

• Vera Deneva,
• Georgi Dobrikov,
• Aurelien Crochet,
• Daniela Nedeltcheva,
• Katharina M. Fromm and
• Liudmil Antonov

Beilstein J. Org. Chem. 2019, 15, 1898–1906, doi:10.3762/bjoc.15.185

• mechanism [20][21][22][23][24][25]. The solvent effect was described using the Polarizable Continuum Model (the integral equation formalism variant, IEFPCM, as implemented in Gaussian 09) [26]. All ground state structures were optimized without restrictions, using tight optimization criteria and an

Synthesis of non-racemic 4-nitro-2-sulfonylbutan-1-ones via Ni(II)-catalyzed asymmetric Michael reaction of β-ketosulfones

• Alexander N. Reznikov,
• Anastasiya E. Sibiryakova,
• Marat R. Baimuratov,
• Eugene V. Golovin,
• Victor B. Rybakov and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2019, 15, 1289–1297, doi:10.3762/bjoc.15.127

• . The study of the solvent effect on the reaction are summarized in Table 2. As can be seen from Table 2, the dr value decreases when using more polar solvents. An individual diastereomer 8a is formed when toluene is used as a solvent (Table 2, entry 1). The highest reaction rate and enantioselectivity

• the asymmetric addition of 1-phenyl-2-(phenylsulfonyl)ethan-1-one (5) to ω-nitrostyrene (6a)a. Solvent effect on the reaction of 1-phenyl-2-(phenylsulfonyl)ethan-1-one (5a) with ω-nitrostyrene (6a)a. Asymmetric addition of β-ketosulfones to nitroalkenes in the presence of complex 7aa. Supporting

Precious metal-free molecular machines for solar thermal energy storage

• Meglena I. Kandinska,
• Snejana M. Kitova,
• Vladimira S. Videva,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• Stanislav B. Baluschev,
• Silvia E. Angelova and
• Aleksey A. Vasilev

Beilstein J. Org. Chem. 2019, 15, 1096–1106, doi:10.3762/bjoc.15.106

• solvent effect induced by the acetonitrile solvent environment, the equilibrium geometries of the host–guest constituents and complexes were reoptimized considering the PCM (polarizable continuum model) solvent model [31]. The so-called basis set superposition error (BSSE) was not taken into account for

Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells

• Ayato Yamada,
• Manabu Abe,
• Yoshinobu Nishimura,
• Shoji Ishizaka,
• Masashi Namba,
• Taku Nakashima,
• Kiyofumi Shimoji and
• Noboru Hattori

Beilstein J. Org. Chem. 2019, 15, 863–873, doi:10.3762/bjoc.15.84

• data for the new compounds 2a,b and 5a,b are summarized in Table 1. The absorption maxima of compounds 2 and 5 were observed at ≈370 nm with a molar extinction coefficient ε ≈20000 M−1 cm−1 in both benzene and DMSO. The emission profile showed a significant solvent effect. The fluorescence quantum

• kcal mol−1 more stable than BRb generated from 2b based on DFT calculations at the B3LYP/6-31G(d) level of theory. In DMSO, no significant difference between 2a and 2b was observed for the photochemical release of the TEMPO species, although the solvent effect is not clearly explained. As mentioned

Strong hyperconjugative interactions limit solvent and substituent influence on conformational equilibrium: the case of cis-2-halocyclohexylamines

• Camila B. Francisco,
• Cleverton S. Fernandes,
• Ulisses Z. de Melo,
• Roberto Rittner,
• Gisele F. Gauze and
• Ernani A. Basso

Beilstein J. Org. Chem. 2019, 15, 818–829, doi:10.3762/bjoc.15.79

• expected, due to classical steric effects (syn-1,3-diaxial repulsion). On the other hand, the amine group is usually very sensitive to the solvent effect. In addition, the increase in the halogen size could lead to a shift toward the ae conformer (equatorial halogen). In the studied system, no change was

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