Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• to a complex mixture of products, the transformation of phenylmalonate substrate 16 (n = 0, Ar1 = Ph) in the presence of nucleophile 5 allowed the formation of cyclized indanyl product 17 in a decent 54% yield. Conclusion During this work, we demonstrated that the prenyl motif can be used as a

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• : spectrum at the end of the irradiation. Photometric titration of ct DNA to 3c (A) 3e (B) 3f (C) and 3g (D) (c = 20 µM) in Na phosphate buffer (pH 7.0, T = 20 °C, cNa+ = 16 mM). The arrows indicate the development of the absorption bands during titration. Inset: plot of absorption versus cDNA. Fluorimetric

• titration of ct DNA to 3c (A), 3e (B), 3f (C), and 3g (D) (c = 20 µM) in Na phosphate buffer (pH 7.0, T = 20 °C, cNa+ = 16 mM). The arrows indicate the development of the emission bands during titration. Inset: plot of relative emission intensity versus cDNA. CD (A) and LD (B) spectra of 3f and ct DNA (cDNA

• = 20 µM) in Na phosphate buffer (pH 7.0, T = 20 °C, cNa+ = 16 mM) at LDR = 0 (black), 0.2 (red), 0.5 (green), 1.0 (blue), 1.5 (orange), and 2.0 (magenta). Changes of the absorption (A) and CD (B) spectra during the irradiation of 2e (1) and 2f (2) (c = 20 μM) in the presence of ct DNA (cDNA = 0.1 mM

Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor

• Pengcheng Li,
• Daniel Kowalczyk,
• Johannes Liessem,
• Mohamed M. Elnagar,
• Dariusz Mitoraj,
• Radim Beranek and
• Dirk Ziegenbalg

Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9

• ) processes, and photocatalysis. Upon upscaling, both PV-E and PEC reactors exhibit pH gradients at electrodes and elevated solution electrical resistivity. These challenges arise from the substantial separation between reduction and oxidation sites, alongside mass transport restrictions in the liquid phase

Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• , 4JP-C = 2.2 Hz, CCH3), 96.6 (d, 1JP-C = 99.0 Hz, C6), 124.6 (d, 1JP-C = 86.0 Hz, Ci-Ph), 127.3 (d, 2JP-C = 12.5 Hz, C5), 129.4 (d, 3JP-C = 11.9 Hz, C4), 131.3 (d, 4JP-C = 1.4 Hz, C3), 132.6 (d, 3JP-C = 9.3 Hz, C2), 132.9 (d, 3JP-C = 2.7 Hz, Cm-Ph), 133.4 (d, 2JP-C = 14.8 Hz, Co-Ph), 140.5 (d, 4JP-C

• = 8.0 Hz, Cp-Ph), 174.1 (d, 2JP-C = 4.4 Hz, C1), 174.8 (d, 3JP-C = 13.9 Hz, CO); 31P{1H} NMR (δ in ppm, 162 MHz, CDCl3, 298 K) 25.1; UV–vis (CHCl3): λmax = 352 nm (ε = 5.53 × 103 L mol−1 cm−1). 1H NMR spectrum of 2a recorded on a 300 MHz spectrometer in CDCl3 at 23 °C; the inset shows a 3D-model based

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

• Lorenzo Catti,
• Shinji Aoyama and
• Michito Yoshizawa

Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5

• , and graphene nanoplatelets) are achieved through noncovalent encircling with the bent amphiphiles. The resultant imidazole-modified nanocarbons display a pH-responsive surface charge, as evidenced by NMR and zeta-potential measurements. In addition, solubilization of a nitrogen-doped nanocarbon (i.e

• pyridinium-based amphiphiles (Figure 1c). The noncovalent modification of C60 with multiple imidazole side-chains is found to yield a pH-responsive surface charge, as evidenced by NMR and zeta-potential measurements. A nitrogen-doped nanocarbon, i.e., graphitic carbon nitride (g-C3N4), is likewise

• through the template effect of the hydrophobic nanocarbon guests (Table 2). Moreover, aromatic micelle (PA-Im)n and its host–guest composite (PA-Im)n·(C60)m were anticipated to provide pH-dependent ZPs via imidazole-based protonation/deprotonation. Micelle (PA-Im)n showed a significantly higher ZP (41.7

Identification of the p-coumaric acid biosynthetic gene cluster in Kutzneria albida: insights into the diazotization-dependent deamination pathway

• Seiji Kawai,
• Akito Yamada,
• Yohei Katsuyama and
• Yasuo Ohnishi

Beilstein J. Org. Chem. 2024, 20, 1–11, doi:10.3762/bjoc.20.1

• metabolites were extracted with 5 mL of ethyl acetate after adjusting the pH to approximately 4 by adding 6 M HCl. The ethyl acetate layer was collected, and it was washed with an equal volume of distilled water to remove the compounds that can be dissolved in water. The ethyl acetate layer was then collected

• (15 mg/L) was added to the culture, and the culture was continued for another 1 day. The pH was adjusted to 4 by adding 6 M HCl to the culture, and the metabolites were extracted by ethyl acetate. After the ethyl acetate was evaporated, the metabolites were absorbed for 5.0 g silica gel 60 (0.040

• were harvested by centrifugation and suspended in lysis buffer (20 mM HEPES-NaOH, 10% glycerol, and 200 mM NaCl2; pH 8.0). The cells were disrupted by sonication on ice, and cell debris was removed by centrifugation. The recombinant protein was purified using His60 Ni Superflow Resin (TaKaRa Bio Inc

Aldiminium and 1,2,3-triazolium dithiocarboxylate zwitterions derived from cyclic (alkyl)(amino) and mesoionic carbenes

• Nedra Touj,
• François Mazars,
• Guillermo Zaragoza and
• Lionel Delaude

Beilstein J. Org. Chem. 2023, 19, 1947–1956, doi:10.3762/bjoc.19.145

• of MIC precursors [24][25][26][27][28]. By analogy with the archetypical NHCs bearing mesityl (Mes) or 2,6-diisopropylphenyl (Dipp) substituents on their nitrogen atoms, we have prepared three triazole derivatives with mixed Mes/Ph, Mes/Bu, or Dipp/Ph substituents on N1 and C4, respectively (Scheme 3

• ) with thermal ellipsoids drawn at the 50% probability level. ORTEP representations of zwitterions 6b (MIC-Dip-Ph-Me·CS2, top) and 6e (MIC-Mes-Bu-Me·CS2, bottom) with thermal ellipsoids drawn at the 50% probability level. Synthesis of CAAC·CS2 zwitterion 2 from its free carbene parent 1. Synthesis of

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

• acid ester 9 was hydrolyzed under basic conditions in an ethanol/water mixture. After the reaction, the pH of the mixture was adjusted to 4 with hydrochloric acid, which resulted in the precipitation of the product 10 in excellent yield (95%). Next, carboxylic acid 10 was converted into the

• , trifluoroacetic acid (5.74 mL, 75 mmol, 63 equiv) was added dropwise. The reaction mixture was stirred at room temperature for 1 h. Then, it was cooled to 0 °C, and a 40% NaOH(aq) solution was added to set the pH to 13. To this mixture, water (60 mL) was added, and it was extracted with DCM/MeOH 20:1 (60 mL

Charge carrier transport in perylene-based and pyrene-based columnar liquid crystals

• Alessandro L. Alves,
• Simone V. Bernardino,
• Carlos H. Stadtlober,
• Edivandro Girotto,
• Giliandro Farias,
• Rodney M. do Nascimento,
• Sergio F. Curcio,
• Thiago Cazati,
• Marta E. R. Dotto,
• Juliana Eccher,
• Leonardo N. Furini,
• Hugo Gallardo,
• Harald Bock and
• Ivan H. Bechtold

Beilstein J. Org. Chem. 2023, 19, 1755–1765, doi:10.3762/bjoc.19.128

• scientifique avec le Brésil) (joint project Ph-C 962/20) for support.

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• stability in aqueous medium. Thus, the electronic absorption spectra of hdz-CH3 and hdz-NO2 were recorded in a 10% DMSO/buffer solution (pH 7.4) immediately after preparation and at regular time intervals. The UV–vis spectrum of hdz-CH3 between 250 and 450 nm (Figure 6A) shows two multicomponent absorptions

• of the resulting hydrazone: a considerable amount of hdz-NO2 deprotonates immediately upon dilution in the aqueous-rich medium at pH 7.4, affording a deep yellow solution due to phenolate-based absorptions centered at around 440 nm. For this reason, we decided to investigate this deprotonation by

• registering the UV–vis spectra of a series of hdz-NO2 10% DMSO/buffer (acetate, phosphate or Tris-HCl) solutions with different pH values, ranging from 3.8 to 8.2 (Figure 7A). By plotting the absorbance at λmax as a function of pH and then fitting the curve with a sigmoidal function (Figure 7A, inset), an

Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds

• Xiaofeng Zhang,
• Xiaoming Ma and
• Wei Zhang

Beilstein J. Org. Chem. 2023, 19, 1677–1693, doi:10.3762/bjoc.19.123

• , serine, and norvaline to give products 11a–f in 53–88% yields with greater than 8.5 dr (Scheme 7). The reactions with leucine and phenylglycine (R2 = iPr and Ph) as amino acids gave mainly mono-cycloaddition products and very little double cycloaddition products 11g and 11h due to the steric hindrance of

• -aminoisobutyric acid, phenylglycine and valine with Ph or iPr groups could also be used for the synthesis of the monocycloaddition products for the post-condensation reactions. It is worth noting that in the one-pot synthesis involving an intramolecular click reaction, no Cu catalyst was used. A similar reaction

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

• the aromatic ring of the 1g+I− is 41.5°, close to the range of values previously reported for 1b+ salts (42.5–52.5°) [19][34] and for salts of Y = Ph, R = R' = H cations with different counterions (42.0–54.9°) [51][52][53]. As expected, owing to reduced steric interactions associated with the five

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

• –substrate interface. The mfp's contain up to 27 mol % of DOPA (ʟ-3,4-dihydroxyphenylalanine), which plays a crucial role on mussel adhesion [11]. Although the crucial role of DOPA in mussel adhesion is not fully understood, a prevailing view suggests that DOPA can be oxidized to o-quinones at an acidic pH

• and the quinones react with unoxidized catechols to form o-semiquinone radicals afterwards [12]. The semiquinone radicals can help DOPA adhere onto organic surfaces. At a basic pH, the system is cured and mechanically stabilized through the formation of DOPA-metal coordination bonds. The cohesion of

Cyclodextrins permeabilize DPPC liposome membranes: a focus on cholesterol content, cyclodextrin type, and concentration

• Ghenwa Nasr,
• Hélène Greige-Gerges,
• Sophie Fourmentin,
• Abdelhamid Elaissari and
• Nathalie Khreich

Beilstein J. Org. Chem. 2023, 19, 1570–1579, doi:10.3762/bjoc.19.115

• ether/methanol 6:6:1 (v/v/v). After a short sonication, the aqueous phase made of SRB (150 mM) dissolved in Tris HCl buffer (0.1 M, pH 7.4) was added to the lipid solution and the mixture was sonicated at 60 °C under a nitrogen stream. The removal of organic solvents was achieved by evaporation at 45 °C

• , 4 °C) and a molecular sieves chromatography (using a Sephadex G25 gel filtration column). A Tris HCl buffer (0.1 M, pH 7.4) containing 150 mM NaCl was used for elution and liposome storage. Exposure of SRB-loaded liposomes to CDs The concentration of DPPC was determined for each formulation

• liposomes of each formulation treated or not with CDs were incubated in a water bath at 37 °C. Aliquots were taken from each sample at 0, 4, and 24 h and the fluorescence signal was measured after a dilution of 100 times in the Tris HCl (0.1 M, pH 7.4) buffer containing 150 mM NaCl. The measurements were

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

• Stéphanie Hesse

Beilstein J. Org. Chem. 2023, 19, 1537–1544, doi:10.3762/bjoc.19.110

• characterized; a pH value of 10.07 was measured at 30 °C by Shah et al. [16] and a viscosity of 750 cP at 25 °C was reported by Mjalli et al. [17] (Table 1). It remains today one of the most used DES and studies on it are still conducted [14]. ChCl/glycerol (ChCl/Gly; 1:2) is another classical DES with a

• synthesis of NaDES plays a major role in the resulting viscosity [20]. For example, ʟ-proline/glycerol (Pro/Gly; 1:2) was found to have a pH value of 7.25 and a viscosity of 5064 cP [20]. In 2018, Molnar et al. reported the antioxidant activity of a series of rhodanine derivatives synthesized by a

Complexes of resorcin[4]arene with secondary amines: synthesis, solvent influence on “in-out” structure, and theoretical calculations of non-covalent interactions

• Waldemar Iwanek

Beilstein J. Org. Chem. 2023, 19, 1525–1536, doi:10.3762/bjoc.19.109

• the amine nitrogen of the guest molecule. In addition to hydrogen bonding, other interactions such as π–π stacking and electrostatic interactions also play a role in the complexation process. These interactions can be modulated by changing the pH, solvent, and temperature of the solution. The binding

Functions of enzyme domains in 2-methylisoborneol biosynthesis and enzymatic synthesis of non-natural analogs

• Binbin Gu,
• Lin-Fu Liang and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1452–1459, doi:10.3762/bjoc.19.104

• added dropwise. The mixture was stirred overnight and the solvent was removed under reduced pressure. The resulting residue was dissolved in aqueous NH4HCO3 solution (0.25 M) and loaded onto a DOWEX 50WX8 ion-exchange column (NH4+ form, pH 7.0). The column was flushed slowly with 1.5 column volumes of

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• -butylthiolate clusters [41]. Following a similar strategy, a series of silyl and stannyl-substituted NHC–Cu(I) complexes were prepared through the reaction of [(NHC)Cu–Ot-Bu] with the respective silyl and stannylboranes. In addition, it was possible to obtain phenyl and alkynyl complexes [(NHC)Cu–R] (R = Ph, CC

• -Ph) in this manner (Scheme 29) [42]. The X-ray studies revealed two major structure types of the compounds [(NHC)Cu-ER3] in the solid state. In the case of bulky NHC ligands, such as IDipp, IMes, and It-Bu, the CuI complexes with ER3 = SiMe2Ph, SiPh3, SnMe3 as well as for Ph and CC-Ph, have monomeric

• , Me, C≡C-n-hep, Ph, CO2Me) and trialkylaluminum (alkyl = Me, Et, iBu) were used for the reactions. This approach is particularly attractive for asymmetric conjugate additions to pentenones, which are otherwise difficult to accomplish. 2.2.3 Reaction with organoboron reagents: In 2010, Hoveyda and co

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

Metal catalyst-free N-allylation/alkylation of imidazole and benzimidazole with Morita–Baylis–Hillman (MBH) alcohols and acetates

• Olfa Mhasni,
• Jalloul Bouajila and
• Farhat Rezgui

Beilstein J. Org. Chem. 2023, 19, 1251–1258, doi:10.3762/bjoc.19.93

• solvent of choice for the reaction using DABCO as additive. Next, the treatment of acrylate-derived alcohols 1b,c (1b, EWG = CO2Et, R = Ph; 1c, EWG = CO2Me, R = Me) [41], under the previously optimized conditions afforded the corresponding 1,4-adducts 8b,c in 70–75% yield (Table 3, entries 2 and 3), as 55

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

• ]. It is important to note that unless special electrodes (ultra microelectrodes) or cells are used, voltammetric measurements of redox potentials require an ionically conductive salt to be added to the solution [19]. Oxidation and reduction potentials can vary with factors such as pH [14][15] and

• NADH-analogues are the subject of most studies for recycling sacrificial donors. NADH has been electrochemically recycled but a careful control of pH is required to prevent dimerization reactions [44][45]. For example, Glusac and co-workers recycled BIH and acridine analogues using platinum electrodes

• photosensitizers is important for designing photocatalytic systems. Potential electron donors can be screened by comparing their oxidation potential to the redox potentials of the photosensitizer. Because redox potentials are solvent and pH-dependent, it is important to compare potentials recorded in conditions as

Two new lanostanoid glycosides isolated from a Kenyan polypore Fomitopsis carnea

• Winnie Chemutai Sum,
• Sherif S. Ebada,
• Didsanutda Gonkhom,
• Cony Decock,
• Rémy Bertrand Teponno,
• Josphat Clement Matasyoh and
• Marc Stadler

Beilstein J. Org. Chem. 2023, 19, 1161–1169, doi:10.3762/bjoc.19.84

• , cotton seed flour 5 g/L in distilled water), were mixed, pH adjusted to 7.2, and autoclaved. The media flasks were inoculated with 10 mycelial plugs (5 mm) each and incubated for 28 days, under shaking and static conditions for liquid and solid cultures, respectively. The cultures were extracted after

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

• substituents on the NI unit (NI-PTZ-F, NI-PTZ-Ph, NI-PTZ-CH3, NI-PTZ-OCH3), and the electron-donating ability of the PTZ unit was modified by oxidation of the sulfur atom to the sulfoxide (NI-PTZ-F-O, NI-PTZ-Ph-O, NI-PTZ-C5-O). The advantage of the oxidation approach is that almost only the energy of the 1CS

• unit (Figure 2e and 2f) [57]. Moreover, it is noted that the CS emission wavelength of NI-PTZ-F-O and NI-PTZ-Ph-O is different from a 4-diphenylamino-substituted NI [58]. These results indicate that the 1CS state of these two dyads involves the oxidized PTZ unit as a whole electron donor, not only the

• N atom of the PTZ unit [59][60]. Further, the NI-PTZ-F-O and NI-PTZ-Ph-O compounds adopt an orthogonal geometry, and the N atom in the PTZ unit is not in π-conjugation with NI moiety due to a conformational restriction [55]. Thus, it is not the ordinary intramolecular charge transfer (ICT) state

CO₂ complexation with cyclodextrins

• Cecilie Høgfeldt Jessen,
• Jesper Bendix,
• Theis Brock Nannestad,
• Heloisa Bordallo,
• Martin Jæger Pedersen,
• Christian Marcus Pedersen and
• Mikael Bols

Beilstein J. Org. Chem. 2023, 19, 1021–1027, doi:10.3762/bjoc.19.78

• change in spectrum of 7 provided 7 and CO2 compete for the binding site. To avoid problems with formation of hydrogencarbonate the experiments were conducted in a buffer at pH 3 where only a minor fraction of the carbonic acid (pKa1 = 3.6) is dissociated and since the hydration constant of CO2 is small

• (1.7 × 10–3) more than 99% of CO2 in solution is the dissolved gas at this pH. First the dissociation constants of 7–CD complexes at pH 3, were determined (Table 2). When a solution of 7 and excess cyclodextrin was subjected to a CO2 atmosphere at 2–8 bar in the pressure cell this gave, after

• coverage of the bottom. The analysis shown in Figure 3 was started at 28 °C, and was finished at a temperature of 150 °C with a heating rate of 5 °C/min. Determination of dissociation constants between 7 and CD’s. Samples were prepared that consisted of citrate-phosphate buffer (pH 3, 50 mM), 7 (40 μM) and