Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• according to: where ΔGdiss(12) is the free-energy change for dissociation of 12 to 1• (dissociation energetics are not estimated in the present work, but have been estimated using DFT calculations for 1b–e2 in previous works [8][14] and, in favorable cases, can be experimentally estimated using electron

• of 1H dopants is given by: where ΔGdiss(1H) is the free-energy change for dissociation of 1H to 1• and H• (again, not discussed in this work), and ΔGdiss(H2) the free-energy change for dissociation of dihydrogen. The values of E(1+/1•) are also relevant to the kinetics of steps in doping reactions

Sulfur-containing spiroketals from Breynia disticha and evaluations of their anti-inflammatory effect

• Ken-ichi Nakashima,
• Naohito Abe,
• Masayoshi Oyama,
• Hiroko Murata and
• Makoto Inoue

Beilstein J. Org. Chem. 2023, 19, 1604–1614, doi:10.3762/bjoc.19.117

• ′, and 24 conformers for 3. The geometry of each conformer was optimized using DFT calculations at the B3LYP/6-31G(d) level of theory [20][21] with the conductor-like polarizable continuum model (CPCM) solvent model (MeOH) and Gibbs free energy was calculated subsequent frequency calculations. Time

• -dependent (TD)-DFT calculations at the B3LYP/6-31+G(d,p) level with CPCM solvent model (MeOH) [22] were performed for the optimized conformers. The resulting ECD spectra calculated for each conformer were averaged using Boltzmann populations evaluated at 300 K from Gibbs free energy calculated from the

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• negative free energy of polymerization and the latter an adequate reactivity of the monomer, stability of the derived free radical, and a low proportion of side reactions. A slow rate of chain initiation, a fast rate of chain propagation, and a rapid rate of chain termination are key features of

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• regeneration to occur. As shown in Figure 1, the scale of electrochemical potential measured in volts is an inverted scale of free energy. Therefore, it is thermodynamically favorable for electrons to be transferred from higher energy sacrificial donor orbitals with less positive oxidation potentials to lower

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• . The Gibbs free energy changes (ΔGCS) for charge separation (CS) as well as the energy of the charge transfer states (ECS) were calculated using the Rehm–Weller equation (Equations 1–3) and the obtained values are listed in Table 4 [62][63][64]. It should be noted that the E00 values used in the

Access to cyclopropanes with geminal trifluoromethyl and difluoromethylphosphonate groups

• Ita Hajdin,
• Romana Pajkert,
• Mira Keßler,
• Jianlin Han,
• Haibo Mei and
• Gerd-Volker Röschenthaler

Beilstein J. Org. Chem. 2023, 19, 541–549, doi:10.3762/bjoc.19.39

• adds to the diazo compound 5 under formation of zwitterionic Int1 (ΔG = 5.2 kcal/mol). Afterwards, copper carbene complex Int2 is formed after extrusion of nitrogen. The transition state of this metal carbene formation TS1 was calculated with an activation free energy of 16.4 kcal/mol (Scheme 5). Int2

• Int2 yielding Int4_3 and Int4_4 without further intermediates. Formation of the products Pr1 to Pr4. Optimization of the reaction conditionsa. Change in Gibbs free energy ΔG (kcal∙mol−1) from the CuI-catalyzed cyclopropanation of the diazo compound with styrene for possible stereoisomers Pr1 to Pr4

Group 13 exchange and transborylation in catalysis

• Dominic R. Willcox and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28

• kinetic and computational analyses, the B‒C(sp2)/B‒H transborylation transition state was determined to have a free energy barrier of approximately 20 kcal mol−1 (ΔG‡calc = 19.7 kcal mol−1; ΔG‡exp = 20.3 kcal mol−1) (Scheme 2). The borane-catalysed hydroboration of alkenes has been less explored, with

• experimentally determined free energy barrier of 28 kcal mol−1 for the second transborylation reaction (Scheme 3b) [60]. The seminal work from Fontaine reported that [1-(N-2,2,6,6-tetramethylpiperidinyl)-2-BH2-C6H4]2 catalysed the C–H borylation of heterocycles with HBpin [61], the first example of a catalytic

• discovered, leaving an exciting future for main group catalysis underpinned by group 13 exchange and transborylation reactions (Figure 1). a) The number of reports for a given group 13 exchange in catalysis. b) Average free energy barrier to group 13 exchange in catalysis (blank where no free energy value

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• process was explained by the unusual feature in the reactivity of the HSPyf/(SPyf)2 pair compared to other thiols and disulfides revealed by DFT calculations. In the case of the SPyf moiety the free-energy barrier for HAT between C-centered radicals and HSPyf is higher than the barrier for an SPyf group

• high hydrogen binding energy and low deprotonation free energy. N-Ammonium ylides were used for the electrochemical oxidation of unactivated C–H bonds (Scheme 37). Ylides showed good selectivity and an unusual reactivity pattern in comparison with known mediators for CH-oxidation. For example, a

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• , USA), to the two independent binding sites model. From the fit, the stoichiometry (n), binding enthalpy change (ΔH, kJ·mol−1), affinity constant (Ka, M−1), binding free energy change (ΔG, kJ·mol−1), and binding entropy change (ΔS, J·mol–1·K−1) for the first binding site were calculated. The

Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence

• Kaiyue Ye,
• Liyuan Cao,
• Davita M. E. van Raamsdonk,
• Zhijia Wang,
• Jianzhang Zhao,
• Daniel Escudero and
• Denis Jacquemin

Beilstein J. Org. Chem. 2022, 18, 1435–1453, doi:10.3762/bjoc.18.149

• , ΦΔ are much larger, up to 100% in dichloromethane (DCM) and ACN, likely due to the heavy-atom effect. Electrochemistry study The redox potentials of the dyads were studied with cyclovoltammetry (Figure 6, Table 3), and the Gibbs free energy changes of the charge separation (ΔGCS) and charge

Ferrocenoyl-adenines: substituent effects on regioselective acylation

• Mateja Toma,
• Gabrijel Zubčić,
• Jasmina Lapić,
• Senka Djaković,
• Davor Šakić and
• Valerije Vrček

Beilstein J. Org. Chem. 2022, 18, 1270–1277, doi:10.3762/bjoc.18.133

• 9H-purine structure. B3LYP/6-31+G(d)/SDD optimized transition state structures for N7- (6-TSN7) and N9-ferrocenoylation (6-TSN9) of the adenine anion 6. Two bulky tert-butyloxycarbonyl groups are displayed in the tube mode for clarity. Relation between the Gibbs free energy barrier (ΔG‡) for the N7

Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Nguyen Ngoc Tri,
• Luc Van Meervelt,
• Nguyen Tien Trung and
• Wim Dehaen

Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118

• reactants, intermediates, transition states, and products were optimized and are illustrated in Figure S7 in Supporting Information File 1. The relative free energy (ΔG, ΔG#) values for all species are presented in Figure 4, the reaction potential energy surface. This figure is a detailed reaction mechanism

• bond to N atom (Scheme 4). This process is thermodynamically favorable by a Gibbs free energy (ΔG) of −6.5 kcal·mol−1. In addition, a second way from 4a, through the TS5 transition state, to form the IS3 intermediate requires an activation energy of ca. 33.7 kcal·mol−1. IS3 could release one H2O

• favorable than from –OH and –NH groups. Moreover, the reaction mechanism in the chloroform and DMSO solvent model is also considered to confirm the main reaction pathway (Table S3 in Supporting Information File 1). The results indicate that the same trends and slight differences of free energy values are

A Streptomyces P450 enzyme dimerizes isoflavones from plants

• Run-Zhou Liu,
• Shanchong Chen and
• Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

• the 2 kJ/mol energy window were generated and optimized using DFT calculations at the B3LYP/6-31+G (d,p) level. Frequency calculations were performed at the same level to confirm that each optimized conformer was true minimum and to estimate the relative thermal free energy (ΔG) at 298.15 K. The two

Understanding the competing pathways leading to hydropyrene and isoelisabethatriene

• Shani Zev,
• Marion Ringel,
• Ronja Driller,
• Bernhard Loll,
• Thomas Brück and
• Dan T. Major

Beilstein J. Org. Chem. 2022, 18, 972–978, doi:10.3762/bjoc.18.97

• ). We studied the inherent chemistry of the reaction leading to HP and IE using gas-phase calculations. This provided the free energy of distinct carbocation intermediates and transition states along the proposed reaction path leading to products in the gas phase. The gas phase is a natural choice as a

• reference environment for terpene synthases [10][11][12][15][16][21][22][23][24][25]. The proposed reaction mechanisms yielding HP and IE and are presented in Scheme 1, while the reaction free energy profile is presented in Figure 2. Here, we modeled the transformations A→I (HP) and A’→E’ (IE). The gas

• any free energy barrier. The deprotonation and re-protonation steps are not included in our calculations. The overall exergonicity of this process which transforms four π-bonds to σ-bonds, with accompanying gains in intramolecular dispersion interactions, is −62.8 kcal/mol. IE pathway As described

Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds: density functional theory study on product selectivity

• Naoki Kise and
• Toshihiko Sakurai

Beilstein J. Org. Chem. 2022, 18, 956–962, doi:10.3762/bjoc.18.95

• step using the DFT method at the B3LYP/6-311+(2d,p)/IEFPCM(THF) level of theory (Supporting Information File 1). From the calculation results for the reactions of 1a–h with 2a summarized in Table 4, it was found that the ratio of D:E calculated from the free energy difference between D and E (∆G) and

• -oxobutyl)phthalides 5 were produced as the sole products by the reaction of 1 with methyl vinyl ketone (2b). It was found by DFT calculations for the cyclization step of the intermediate enolate anions that the product selectivity was in good agreement with the free energy differences (∆G) in the

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

• during protonation of Ruhemann's purple. Although there was conclusive evidence of the structure of PRP (1) in the Grigg's study (proven by X-ray analysis) [27], we aimed to establish a stability order of tautomers on the basis of calculated relative values of the Gibbs free energy. Upon treatment of

• the most basic site in the molecule. We carried out full geometry optimization of all possible tautomers 1, 1', 1'', and aza-allylic anion Ruhemann's purple to calculate the Gibbs free energy change for the corresponding acid–base reactions (Scheme 7). As expected, the calculation data showed that the

• , respectively. In turn, the Gibbs energies of activation corresponding to the endo approaches indicate that cycloadduct 4 (ΔG‡1+2j->4-endo = 19.3 kcal/mol) is more kinetically favorable than its epimer 4' (ΔG‡1+2j->4'-endo = 20.3 kcal/mol). The small free energy difference (1.0 kcal/mol) between the two

Terpenoids from Glechoma hederacea var. longituba and their biological activities

• Dong Hyun Kim,
• Song Lim Ham,
• Zahra Khan,
• Sun Yeou Kim,
• Sang Un Choi,
• Chung Sub Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2022, 18, 555–566, doi:10.3762/bjoc.18.58

• based on the Boltzmann populations of each conformer in the associated Gibbs free energy (Supporting Information File 1, Figure S45). The ECD spectra were Boltzmann-weighted and generated using SpecDis software (Version 1.71) [23] with a σ/γ value of 0.30 eV. The chemical shift values were calculated

Iridium-catalyzed hydroacylation reactions of C1-substituted oxabenzonorbornadienes with salicylaldehyde: an experimental and computational study

• Angel Ho,
• Austin Pounder,
• Krish Valluru,
• Leanne D. Chen and
• William Tam

Beilstein J. Org. Chem. 2022, 18, 251–261, doi:10.3762/bjoc.18.30

• iridium–hydride bond to form hydrometalated intermediates IN2a and IN2b (Figure 1). Two possible transition states, which exhibit a distorted Ir–H–C–C’ four-membered ring geometry, can be located. The concerning free energy barrier about IN1a to IN2a, via 1aTS2a is 8.6 kcal/mol whereas it is 4.9 kcal/mol

• last key step in the catalytic cycle involves the C–C bond-forming reductive elimination to form the final ketone intermediate IN3a or IN3b (Figure 1). Two possible transition states, 2aTS3a and 2bTS3b, can be located. The concerning free energy barrier about IN2a to IN3a, via 2aTS3a is 10.8 kcal/mol

• transition states in both reaction pathways, it is determined the reductive elimination step is the rate-determining step (RDS) for the active bond-forming hydroacylation catalytic cycle, as it possesses the greatest free energy barriers. This parallels that determined by Morehead and Sargent who

Mechanistic studies of the solvolysis of alkanesulfonyl and arenesulfonyl halides

• Malcolm J. D’Souza and
• Dennis N. Kevill

Beilstein J. Org. Chem. 2022, 18, 120–132, doi:10.3762/bjoc.18.13

• . However, if one is willing to settle for a classification of the mechanism as unimolecular or bimolecular accompanied by an approximate measure of the extents of bond-making and bond-breaking at the sulfur atom involved at the transition state, one can use a linear free energy relationship (LFER) approach

Efficient and regioselective synthesis of dihydroxy-substituted 2-aminocyclooctane-1-carboxylic acid and its bicyclic derivatives

• İlknur Polat,
• Selçuk Eşsiz,
• Uğur Bozkaya and
• Emine Salamci

Beilstein J. Org. Chem. 2022, 18, 77–85, doi:10.3762/bjoc.18.7

• reaction free energy and barrier are −9.5 and 14.5 kcal mol−1 with methanol, respectively and −11.1 and 13.5 kcal mol−1 with dichloromethane, respectively (Figure 3). For the formation of the five-membered lactone 18 (path a), 17 → 18, the reaction proceeds via a barrierless path and the solvent corrected

• reaction free energies are −17.2 and −18.0 kcal mol−1 with methanol and dichloromethane, respectively. For the formation of the six-membered lactone 19 (path b), 17 → 19, the solvent corrected reaction free energy and barrier are −5.4 and 14.5 kcal mol−1 in methanol, respectively and −7.1 and 13.4 kcal mol

• epoxide 7, the relative free energy of 7b is higher by 10.3 kcal mol−1 than that of 7a (Figure 5). Conclusion In summary, we successfully synthesized hydroxylated cyclooctane β-amino acid 6 and its derivatives 8, 10, and 13 starting from β-lactam 2. The regioselective synthesis of lactone 8, which is a

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• indicated in the two-dimensional projection in the space of PC1 and PC2, where colouring is made by relative free energy as obtained from Boltzmann reweighting using 10th order Maclaurin series expansion [92][93]. In both isomers, the first three clusters represent about 53% of the total conformational

• frame and is coloured according to its corresponding re-weighted relative free energy. Data is calculated on the cumulative last 500 ns of 15 accelerated molecular dynamics runs for each SMC peptide. Molecular modelling of the conformational preferences of the SMC stapled peptides P5 (with cis or trans

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

• , endergonic by 18.8 kcal·mol−1 (gas phase) and 20.1 kcal·mol−1 (1,4-dioxane with PCM); almost thrice the Gibbs free energy for the same reaction with DABCO as a HAT abstractor. The barrierless character is supported by NEB-TS calculations (vide infra) (Supporting Information File 1, Figure S16). Both these

• the Evans–Polanyi principle, that relates the rate coefficients of a reaction step to their free energy (for which the BDE difference is a proxy) [35][36][37]. When considered together with Hammond´s postulate [38], the Evans–Polanyi principle (E-PP) generates the often used rule-of-thumb that good

• catalysts and photocatalysts [9][10][11][12][21][22][23]. Previous reports of DABCO as hydrogen abstractor in HAT reactions and this work. Free energy profile for the HAT step reactions between isovaleraldehyde with (top) DABCO and (bottom) quinuclidine radical cations. The red lines are for the gas phase

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• the Michael adducts has the lowest Gibbs free energy of activation of 40.4 kJ·mol−1. The Gibbs free energies of activations for the (S,S)-C2 catalyst are only slightly higher than those for the (S,R)-C2 catalyst. These calculations support the experimental observation that the configuration of the

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• ; mechanisms of copper photocatalysis; photoinduced copper-based catalysis; photoredox catalysis; special features of copper photocatalysis; Introduction Solar light is an inexhaustible and free energy source for green plants and bacteria. Photosynthetic organisms absorb solar energy and convert it into