Unveiling the regioselectivity of rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions for open-cage C₇₀ production

• Cristina Castanyer,
• Anna Pla-Quintana,
• Anna Roglans,
• Albert Artigas and
• Miquel Solà

Beilstein J. Org. Chem. 2024, 20, 272–279, doi:10.3762/bjoc.20.28

•  1), unveiled the following reaction mechanism: initially, an oxidative coupling of the two alkyne moieties of our model 1a leads to the formation of INT 1, as previously reported [33]. This step, with a Gibbs energy barrier of 25.7 kcal·mol−1, is the rate-determining step for this process. Next, INT

• isomers. B3LYP-D3/cc-pVTZ-PP(SMD=o-DCB)//B3LYP-D3/CC-pVDZ-PP Gibbs energy profile of the [2 + 2 + 2] cycloaddition between our model diyne 1a and C70. Comparison between α- and β-reaction pathways. Black line: α-pathway. Grey line: β-pathway. Molecular structures correspond to the α-pathway. [Rh] = [Rh

• between the rhodacyclopentadiene moiety and a [6,6]-α-bond of C70, yielding rhodabicyclo[3.2.0]heptadiene intermediate α-INT 3. This step has a cost of 9.5 kcal·mol−1. Alternatively, a [6,6]-β-bond of C70 can be involved in this step (grey line) to produce β-INT 3, albeit with a slightly higher Gibbs

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• that the formation of dications D does not take place. Species B should be the key reactive intermediates that undergo cyclization into indanones 3 with a negative Gibbs energy of −7 kJ/mol for the reaction Ba→3a. According to the calculations, the subsequent complete protonation of the hydroxy group

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• binding (∆rH). The reaction Gibbs energies (∆rG) were calculated by using the following equation: ∆rG = −RTln(Ka). The entropic contribution to the binding Gibbs energy was calculated by the equation: T∆rS = ∆rH − ∆rG. Confocal microscopy: HeLa cells were cultured and maintained in complete high glucose

Recommendations for performing measurements of apparent equilibrium constants of enzyme-catalyzed reactions and for reporting the results of these measurements

• Robert N. Goldberg,
• Robert T. Giessmann,
• Peter J. Halling,
• Carsten Kettner and
• Hans V. Westerhoff

Beilstein J. Org. Chem. 2023, 19, 303–316, doi:10.3762/bjoc.19.26

• the apparent equilibrium constant K′ and the standard transformed molar Gibbs energy of reaction (ΔrG'°) for biochemical reactions [11]. STRENDA does not aim at policing authors who report data on enzyme kinetic or on equilibrium measurements. The aim is to aid these researchers by providing

• discussed in reference [11]. Also, it is important to recognize that the Gibbs energy G and the transformed Gibbs energy G′, corresponding to chemical and biochemical reactions, respectively, are state functions. Therefore, values of equilibrium constants and apparent equilibrium constants, respectively

• , are both a property of the reaction itself and are independent of the catalyst used. Indeed, there are some enzyme-catalyzed reactions that will proceed without an enzyme, e.g., carbonic anhydrase or at an elevated temperature. At equilibrium, the molar Gibbs energy of a chemical reaction ΔrG equals

Synthesis of bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via cyclopropene cycloadditions to the stable azomethine ylide derived from Ruhemann's purple

• Alexander S. Filatov,
• Olesya V. Khoroshilova,
• Anna G. Larina,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2022, 18, 769–780, doi:10.3762/bjoc.18.77

• and TS-4'-exo associate with nitrogen invertomers 4'-endo and 4'-exo of cycloadduct 4', respectively. Next, we determined the Gibbs energy of activation for nitrogen inversion in cycloadducts 4 and 4' to figure out if the invertomers undergo rapid interconversion. Having carried out full geometry

• competing pathways is in good agreement with the experimental data and explains the reason why the cycloaddition reaction does not result in the exclusive formation of 4. Additionally, the reaction of PRP (1) with 1-chloro-2-phenylcyclopropene (2m) was investigated to calculate the Gibbs energy of

• states TS-5a-endo and TS-5a-exo that bring about invertomers 5a-endo and 5a-exo of cycloadduct 5a, respectively. According to the values of the Gibbs energy of activation, the endo cycloaddition (ΔG‡ = 12.2 kcal/mol) significantly prevails over the exo one (ΔG‡ = 14.5 kcal/mol). When comparing the values

Constrained thermoresponsive polymers – new insights into fundamentals and applications

• Patricia Flemming,
• Alexander S. Münch,
• Andreas Fery and
• Petra Uhlmann

Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138

• processes in general, and the mixing processes discussed here, has been thermodynamically formulated. Mathematically, this description results in the Gibbs energy of mixing ΔmG, which is linked to the enthalpy of mixing ∆mH and the entropy of mixing ∆mS via the following well-known connection: This means

• that for positive values of ΔmG, segregation occurs and for negative ΔmG, mixing occurs. For an ideal binary mixture of components A and B, this equation can be converted into the following form by comparing the Gibbs energy before and after mixing using the chemical potentials µ: with n = nA + nB. It

• energy for a heterogeneous system over the entire concentration range (illustrated in Figure 1a, curve α). The Gibbs energy of mixing cannot be reduced by demixing, so that A and B are miscible with each other in any ratio. The mixture is always more stable than the pure components. In contrast, the

Pentannulation of N-heterocycles by a tandem gold-catalyzed [3,3]-rearrangement/Nazarov reaction of propargyl ester derivatives: a computational study on the crucial role of the nitrogen atom

• Giovanna Zanella,
• Martina Petrović,
• Dina Scarpi,
• Ernesto G. Occhiato and
• Enrique Gómez-Bengoa

Beilstein J. Org. Chem. 2020, 16, 3059–3068, doi:10.3762/bjoc.16.255

• figure. The values for ΔG correspond to the Gibbs energy computed at the M06/def2tzvpp level of theory in a solvent model (IEFPCM, solvent = DCM). The intrinsic reaction coordinates (IRC) were followed to verify the energy profiles connecting the key transition structures to the correct associated local

Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

• Viola Kolaříková,
• Markéta Rybáčková,
• Martin Svoboda and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2020, 16, 2757–2768, doi:10.3762/bjoc.16.226

• ). The search for the saddle points (starting complexes of both unsaturated compounds 12b and 13, transition states 15A–D and the corresponding Diels–Alder products 14A–D (Figure 4)) showed that the reaction is strongly exergonic and irreversible with an activation free Gibbs energy in the range between

• 46 and 76 kJ/mol. From the activation free Gibbs energy results that two main stereoisomers should be formed, namely the endo-trans 14B (99%) and the exo-cis 14C (1%). The difference among the computed (99% and 1%) and experimentally observed values (29% and 16%) can be explained by a participation

Lipophilicity trends upon fluorination of isopropyl, cyclopropyl and 3-oxetanyl groups

• Benjamin Jeffries,
• Zhong Wang,
• Robert I. Troup,
• Anaïs Goupille,
• Jean-Yves Le Questel,
• Charlene Fallan,
• James S. Scott,
• Elisabetta Chiarparin,
• Jérôme Graton and
• Bruno Linclau

Beilstein J. Org. Chem. 2020, 16, 2141–2150, doi:10.3762/bjoc.16.182

• relates to the difference in Gibbs energy of the free ligand conformations of this solute in the respective solvents. Quantum chemistry calculations of Gibbs energies in octanol and water thus provide theoretical estimations of lipophilicities. Such estimations require systematic conformational analyses

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

• Carlos H. Escalante,
• Eder I. Martínez-Mora,
• Carlos Espinoza-Hicks,
• Alejandro A. Camacho-Dávila,
• Fernando R. Ramos-Morales,
• Francisco Delgado and
• Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

• cycloadditions, the relative energy is summarized in Table 6 and the geometry is displayed in Figure 3. The data indicate a single concerted TS not only for the cycloaddition of 8g/7c, but also for all the endo and exo processes (Supporting Information File 1, Appendix 5). The Gibbs energy was also calculated

• ratio determined through the Gibbs energy (endo/exo, 79.9:20.1) matched better. Actually, the reactivity of diene 8b would be expected to be lower due to a greater deactivation of the cyano group, as suggested by comparing the most stable HOMO of this diene with the values for dienes 8c and 8g

• (Supporting Information File 1, Table S1). Hence, the latter dienes should be more reactive than diene 8b, and consequently more stereoselective [54][55][56]. In contrast, the Gibbs energy for the diene/dienophile 8c/7b (88.8:11.2) did not completely match the experimental endo/exo (99:1) ratio, but the ZPE

Why do thioureas and squaramides slow down the Ireland–Claisen rearrangement?

• Dominika Krištofíková,
• Juraj Filo,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2019, 15, 2948–2957, doi:10.3762/bjoc.15.290

• reaction profile without catalyst is displayed in Figure 5b. In this case, the formation of a small amount of an unidentified byproduct was also observed. The rate constants for the uncatalyzed and catalyzed reaction are similar. The activation Gibbs energy was determined to be approximately 90 kJ·mol−1

Host–guest interactions between p-sulfonatocalix[4]arene and p-sulfonatothiacalix[4]arene and group IA, IIA and f-block metal cations: a DFT/SMD study

• Valya K. Nikolova,
• Cristina V. Kirkova,
• Silvia E. Angelova and
• Todor M. Dudev

Beilstein J. Org. Chem. 2019, 15, 1321–1330, doi:10.3762/bjoc.15.131

• of p-sulfonatocalix[4]arene and some inorganic and organic cations in aqueous solution [32]. The predicted ΔG value (relative Gibbs energy) of the complexation between the host calixarene molecule and hydrated La3+ cation (with an average coordination number of water molecules in the first hydration

• between the products and reactants of electronic energies, ΔEel, thermal energies, incorporating zero-point energy, ΔEth, and entropies, ΔS, in the gas phase (ε = 1) were used to evaluate the Gibbs energy of the complex formation, ΔG1, at T = 298.15 K according to the equation: The counterpoise procedure

Silanediol versus chlorosilanol: hydrolyses and hydrogen-bonding catalyses with fenchole-based silanes

• Falco Fox,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2019, 15, 167–186, doi:10.3762/bjoc.15.17

• hydrolysis to BIFOXSi(OH)2 (9) and comparison with glycoxydichlorosilane. The activation energy (Ea) is the difference of the free Gibbs energy of the educt and the TS and the reaction energy (Er) is the difference the free Gibbs energies of the educts and products of the respective steps side and front1

Synthesis and reactivity of aliphatic sulfur pentafluorides from substituted (pentafluorosulfanyl)benzenes

• Norbert Vida,
• Jiří Václavík and
• Petr Beier

Beilstein J. Org. Chem. 2016, 12, 110–116, doi:10.3762/bjoc.12.12

• selectivity of 16a (98:2) from the differences of Gibbs energy of the transition states. Geometries of the four transition states are depicted in Figure 1. The less abundant transition states (TS-endo-16b and TS-exo-16b) were asynchronous with the differences of bond lengths of 0.662 and 0.556 Å, respectively

Computational study of productive and non-productive cycles in fluoroalkene metathesis

• Markéta Rybáčková,
• Jan Hošek,
• Ondřej Šimůnek,
• Viola Kolaříková and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2015, 11, 2150–2157, doi:10.3762/bjoc.11.232

• inflexion when converted to free Gibbs energy at 25 °C (see Figure 1, dotted red line). At this stage only minimal relative energy differences were observed for the structures 1c and 2c. However, in the next step forming metallacyclobutane the transition state energy was by ca. 20 kJ/mol higher for the syn

Deproto-metallation of N-arylated pyrroles and indoles using a mixed lithium–zinc base and regioselectivity-computed CH acidity relationship

• Mohamed Yacine Ameur Messaoud,
• Ghenia Bentabed-Ababsa,
• Madani Hedidi,
• Aïcha Derdour,
• Floris Chevallier,
• Yury S. Halauko,
• Oleg A. Ivashkevich,
• Vadim E. Matulis,
• Laurent Picot,
• Valérie Thiéry,
• Thierry Roisnel,
• Vincent Dorcet and
• Florence Mongin

Beilstein J. Org. Chem. 2015, 11, 1475–1485, doi:10.3762/bjoc.11.160

• acidity ΔGacid was defined as the Gibbs energy of deprotonation of the particular substrate R–H (R–H(g) → R−(g) + H+(g)): ΔGacid = G0298(R−) + G0298(H+) − G0298(R–H). The solvent influence was simulated within the polarized continuum model (PCM) with the default parameters for THF. The cavity was built up

• using atomic radii from the UFF force field. The PCM energies EPCM were calculated at the B3LYP/6-311+G(d,p) level using geometries optimized for isolated structures. The Gibbs energy in solution Gsol was calculated for each species by the formula: Gsol = G0298 + EPCM − E. The following homodesmic

• substrates. Consequently, the Gibbs energy of the homodesmic reaction (ΔGr,sol) and the pKa value are related by the following equation: Biological evaluation. The antiproliferative activity of N-arylated pyrrole and indole derivatives was studied in the A2058 (ATCC® CRL-11147) cell line as described

First principle investigation of the linker length effects on the thermodynamics of divalent pseudorotaxanes

• Andreas J. Achazi,
• Doreen Mollenhauer and
• Beate Paulus

Beilstein J. Org. Chem. 2015, 11, 687–692, doi:10.3762/bjoc.11.78

• ; Gibbs energy; pseudorotaxanes; solvent effects; COSMO-RS; Introduction If two or more binding sites of a molecular system are involved in the association process, the interaction energy can be significantly increased compared to the sum of the individual binding energies. This effect is called

• contributions, enthalpic and entropic temperature effects as well as solvent effects are included in our simulations in order to compare to experimentally obtained Gibbs energy of association. Results and Discussion In order to investigate the cooperativity effects of the binding between divalent host molecules

• and divalent guest molecules it is important to firstly describe the monovalent binding motif computationally as accurately as possible and to understand the underlying effects that contribute to the binding. Three major terms have to be considered in the evaluation of the Gibbs energy of association

The Ugi four-component reaction as a concise modular synthetic tool for photo-induced electron transfer donor-anthraquinone dyads

• Sarah Bay,
• Gamall Makhloufi,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 1006–1016, doi:10.3762/bjoc.10.100

• for a rapid exergonic depopulation of the excited singlet states into a charge-separated state. Calculations of the Gibbs energy of photo-induced electron transfer from readily available UV–vis spectroscopic and cyclovoltammetric data applying the Weller approximation enables a quick evaluation of

• probability for charge separation by photo-induced electron transfer based upon its Gibbs energy calculated from the analytical data and donor–acceptor distances of lowest energy conformers from inexpensive force field computations. Results and Discussion Synthesis and structure Within the concept of

Synthetic scope and DFT analysis of the chiral binap–gold(I) complex-catalyzed 1,3-dipolar cycloaddition of azlactones with alkenes

• María Martín-Rodríguez,
• Luis M. Castelló,
• Carmen Nájera,
• José M. Sansano,
• Olatz Larrañaga,
• Abel de Cózar and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2013, 9, 2422–2433, doi:10.3762/bjoc.9.280

• outcome of the reaction. We also studied the last step of the catalytic cycle that ensures the recovery of the catalyst obtaining a favourable Gibbs energy of −55.3 kcal mol−1 (Scheme 5). No chemical reaction occurred when 5a was combined with other dipolarophiles such as fumarates, maleates, vinyl phenyl

True and masked three-coordinate T-shaped platinum(II) intermediates

• Manuel A. Ortuño,
• Salvador Conejero and
• Agustí Lledós

Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153

Complete σ* intramolecular aromatic hydroxylation mechanism through O₂ activation by a Schiff base macrocyclic dicopper(I) complex

• Albert Poater and
• Miquel Solà

Beilstein J. Org. Chem. 2013, 9, 585–593, doi:10.3762/bjoc.9.63

• the 18.3 kcal·mol−1 described in the mechanism in Figure 1. Thus, the reactivity towards the aromatic rings of the intermediate trans-peroxo (c) is worse with respect to the intermediate with a peroxo core (d). Finally, comparison of the Gibbs energy profiles of Figure 1 in the present work with those

Organocatalytic asymmetric addition of malonates to unsaturated 1,4-diketones

• Sergei Žari,
• Tiiu Kailas,
• Marina Kudrjashova,
• Mario Öeren,
• Ivar Järving,
• Toomas Tamm,
• Margus Lopp and
• Tõnis Kanger

Beilstein J. Org. Chem. 2012, 8, 1452–1457, doi:10.3762/bjoc.8.165

• were carried out for all favored conformers to verify their stability. The Boltzmann distribution of the Gibbs energy showed that one conformation out of six is dominant (84%). The experimental and calculated IR spectra match well in the range 1500–1800 cm−1 (both experimental and calculated spectra

Recent advances in direct C–H arylation: Methodology, selectivity and mechanism in oxazole series

• Cécile Verrier,
• Pierrik Lassalas,
• Laure Théveau,
• Guy Quéguiner,
• François Trécourt,
• Francis Marsais and
• Christophe Hoarau

Beilstein J. Org. Chem. 2011, 7, 1584–1601, doi:10.3762/bjoc.7.187

• calculations on oxazole-4-carboxylate; (b) Developed novel CMD direct arylation methodologies. aTS CMD Free Gibbs energy; bHOMO coefficient; cpartial charge (ESP). Pd(0)-catalyzed direct arylation of (benz)oxazoles with tosylates and mesylates [71]. Pd(0)-catalyzed direct arylation of oxazoles with sulfamates