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

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• acids, 0.5 g/L glucose, 0.5 g/L soluble starch, 0.3 g/L KH2PO4, 0.05 g/L MgSO4 × 7 H2O. The pH of the medium was adjusted to pH 7.2. The cultivation was conducted on a rotary shaker at 130 rpm and 30 °C for one week. Afterwards adsorber resin (XAD-7, 20 g/L) was added to the culture broth to bind the

First synthesis of acylated nitrocyclopropanes

• Kento Iwai,
• Rikiya Kamidate,
• Khimiya Wada,
• Haruyasu Asahara and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

• the literature [26]. To a solution of ammonium acetate (2.63 g, 36 mmol) in acetic acid (10 mL), were added 4-methylbenzaldehyde (2 mL, 15 mmol) and nitromethane (5.3 mL, 98 mmol), and the resultant mixture was heated at 100 °C for 6 h. After adjusting the pH value to 7 by 2 M sodium hydroxide (40 mL

A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

• Xiaoqian Chen,
• Naqin Yang,
• Yue Ma,
• Xinan Yang and
• Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

• supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via https://www.ccdc.cam.ac.uk/data_request/cif. Supramolecular assembly of TMeQ[6] and 1,2-bis(4-pyridyl)ethene (G). (a) UV–vis titration of G (3.0 × 10−5 mol·L−1, pH

• 6.5) in aqueous solution with the increase of TMeQ[6] concentration; (b) plots of n(TMeQ[6])/n(G) vs ultraviolet absorption of G. (a) Fluorescence spectra (U = 550 V, pH 6.5) of G (3.0 × 10−5 mol·L−1) in aqueous solution with increasing TMeQ[6] concentration; (b) plots of n(TMeQ[6])/n(G) vs

• solution; (b) fluorescence response (λmax,em = 380 nm) of G@TMeQ[6] (1:1, 3.0 × 10−5 mol·L−1) to metal cations in aqueous solution. (c(other metal cations) = 3.0 × 10−4 mol·L−1, U = 520 V, pH 6.5). Influence of coexisting ions on Hg2+ detection by G@TMeQ[6]. (a) Fluorescence titration curve (U = 500 V, pH

Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?

• Lukáš Marek,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61

• structurally related S-ethyl ethanimidothioate and S-ethyl benzimidothioate in aqueous solution, such reaction pathway begins to open [33] at pH > 6 and 8, respectively. The subsequent formation of imidothioates 6a,b''' and their base-catalyzed elimination (Scheme 3) takes place easily, especially in MeCN

• . Experiments as well as quantum calculations have shown that the acidifying effect of a solitary phenyl group (Z = Ph in Scheme 2 and in Figure 2) is not sufficient to enable a successful ECR. On the other hand, if the free rotation of phenyl group (Z) is restricted by its further bonding through a group Y

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• glum of (P,P,M/M,M,P)-117 was measured as 2 × 10−4. Cyclooctatetraphenylene (COT-Ph) is a π-conjugated scaffold, whose three-dimensional (3D) geometry is based on its saddle shape. Martín and co-workers reported the 3D NG 121 by the introduction of four HBC units into COT-Ph [60]. As shown in Scheme 14

• , functionalized COT-Ph reacted with compound 50 through Sonogashira cross-coupling reaction affording compound 119 in a 73% yield. Then Diels–Alder reaction between 119 and 2 gave structure 120 as NG precursor. Compound 120 underwent intramolecular cyclodehydrogenation mediated by FeCl3, affording the final NG

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• , compounds 5a–c (Ar = Ph, 4-MeOC6H4, 4-CF3C6H4) were red-shifted by 18–39 nm relatively to the corresponding monomers. Their absorption maxima were rather close to those of butadiyne 1 end-capped by two DMAN residues. In doubly protonated tetrafluoroborate salts of the oligomers, conjugation between the aryl

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

• Sarot Cheenpracha,
• Ratchanaporn Chokchaisiri,
• Lucksagoon Ganranoo,
• Sareeya Bureekaew,
• Thunwadee Limtharakul and
• Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

• according to experimental literature with slight modification [20]. α-Glucosidase (0.05 U/mL) and substrate, p-nitrophenyl-α-ᴅ-glucopyronoside (p-NPG) (1 mM) were dissolved in 0.1 M sodium phosphate buffer (pH 6.9). Fifty μL of sample (1 mg/mL in 10% DMSO) and 50 μL of α-glucosidase were preincubated at 37

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• , PR China 10.3762/bjoc.19.45 Abstract We synthesized a new tetraphenylethylene-modified chitosan bioconjugate, CS-TPE, that shows the aggregation-induced emission effect. It can self-assemble into fluorescent polymeric nanoparticles in an aqueous solution at pH 5.3 either alone or with the water

• -soluble bowl-shaped six-fold carboxylated tribenzotriquinacene derivative TBTQ-C6 via host–guest binding. The spherical nanoparticles formed by CS-TPE amphiphiles or TBTQ-C6/CS-TPE supra-amphiphiles disintegrated under alkaline stimulation at pH 10.4 and the dispersion of the aggregates after the collapse

• in the presence of TBTQ-C6 was greatly improved. In addition, the fluorescence of CS-TPE was significantly enhanced by introducing TBTQ-C6, and remained relatively stable with variations in pH for both CS-TPE and TBTQ-C6/CS-TPE. Such pH-responsive supramolecular spherical nanoparticles with stable

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

• a pH-dependent excimer formation that is significantly red-shifted relative to the pyrene and phenanthridine fluorescence. While the conjugate with a short linker showed negligible spectrophotometric changes due to the polynucleotide addition, the conjugate with a longer and more flexible linker

• combine to produce an excimer, which is identifiable by a certain fluorescence band [11][12]. Some of the pyrenes and phenanthridines exhibited meaningful biological activity. Several pyrene-guanidiniocarbonylpyrrole derivatives have been found to exhibit the affinity for ds-DNA that is strongly pH

• were moderately soluble in DMSO (up to c = 1 × 10−3 mol dm−3) and their stock solutions were stable during a few months. All measurements were recorded in the Na cacodylate buffer (Ic = 0.05 mol dm−3) both at pH 5.0 and pH 7.0 for comparison, since the phenanthridine heterocyclic nitrogen becomes

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• used directly which showed comparable yields. The authors also reported preliminary results for an asymmetric variant of the reaction using (R,R)-Ph-BPE as a chiral ligand. Although the use of the chiral phosphine ligand resulted in slightly diminished yields, the authors were able to achieve ees up to

• triisopropylsilyl (TIPS) group in 63a was swapped for a Ph (63b). Mechanistically, the reaction operates in a similar manner reported by Hirano and Miura (Scheme 9) [43]; however, the alkyl–Cu species 60 is intercepted by the bromoalkyne rather than an O-benzoylhydroxylamine. In the same year, the Brown laboratory

Dipeptide analogues of fluorinated aminophosphonic acid sodium salts as moderate competitive inhibitors of cathepsin C

• Karolina Wątroba,
• Małgorzata Pawełczak and
• Marcin Kaźmierczak

Beilstein J. Org. Chem. 2023, 19, 434–439, doi:10.3762/bjoc.19.33

• analogues of fluorinated aminophosphonic acid sodium salts 9, 11 with phenylalanine at the N-terminus and evaluated their inhibitory activity against bovine cathepsin C. Inhibition kinetics were carried out at 37 °C for 10 minutes in acetate buffer at pH 5. Changes in product concentration versus time were

• monitored spectrophotometrically at λ = 405 nm. Seven of the tested compounds were moderate competitive inhibitors with millimolar inhibitory activity (Table 2). Three of them at higher concentrations precipitated from 0.1 M acetate buffer at pH 5.0. Dipeptide analogues of α-fluorinated aminophosphonic acid

• of more effective fluorinated inhibitors of cathepsin C in our laboratory. Dixon plot for the hydrolysis of Gly-Phe-pNA substrate catalyzed by bovine cathepsin C in the presence of 9b (T = 37 °C, pH 5.0). Synthetic strategy towards 5 and 7. Synthesis of 9 and 11. (a) R = -CH3; (b) R = -CH(CH3)2; (c

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• Sigma-Aldrich, St. Louis, MO, USA). Finally, 2-propanol (ACS reagent, Reag. Ph. Eur.) used for FTIR cleaning was obtained from Merck & Co., Inc., Rahway, NJ, USA. Gas chromatography–mass spectrometry (GC–MS) The FA profile of the hazelnut oil was determined by GC–MS, after derivatization to FAMEs

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• constructed from the corresponding rhenium complexes by using [99mTc(CO)3(H2O)3]+ at pH 7.4 and 90 °C temperature. Santos et al. [39] reported in 2008 the synthesis of CuAAC-ensembled 1,2,3-triazole-linked porphyrin-quinolone conjugates 70a–e by considering the biological significance of both the porphyrin

• microwave irradiation conditions. The prepared nanoparticles from free-base PPCs showed colorimetric aqueous pH sensing, which suggests that the PPC nanoparticles could serve as chemical sensing applications. In 2008, the Crossley’s group [59] reported the synthesis of a ‘capped’ porphyrin 142 forming a

• -triazol-4-yl)methyl]amine, MW, 70 °C (iii) LiOH, water, room temperature, 3 h (iv) phosphate buffer pH 7, [Re(CO)3Br3][NEt4]2, 65 °C, 2 h (v) [99mTc(CO)3(H2O)3]+, pH 7.4, 90 °C, 30 min. Synthesis of meso-triazole-bridged porphyrin-quinolone conjugates 70a–e. Synthesis of meso-triazole-linked porphyrin

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

• -hydroboration of the enone 29 with H-B-9-BBN to give an O-B-9-BBN enolate 30. Electrophilic cyanation of the enolate 30 with NCTS 31, and elimination gave the β-ketonitrile 33 and TsN(Ph)-9-B-BBN 34, which underwent B‒N/B‒H transborylation with HBpin to regenerate the catalyst and give TsN(Ph)-Bpin 35 (Scheme 8

• isotopic labelling and proposed to proceed by hydroboration of the allene 62 by the borane catalyst (H-B-9-BBN or 10-phenyl-9-borabicyclo[3.3.2]decane [Ph-BBD]) followed by rapid isomerisation from the (Z)-63 to (E)-allylborane 64 which underwent allylation of the ketone 65 to give an allylic borinic ester

• carbonates and the proposed mechanism. H-B-9-BBN-catalysed reductive aldol-type reaction and the proposed mechanism. H-B-9-BBN-catalysed diastereoselective allylation of ketones and the Ph-BBD-catalysed enantioselective allylation of ketones and the proposed mechanism. H-B-9-BBN-catalysed C–F arylation of

Synthesis and reactivity of azole-based iodazinium salts

• Thomas J. Kuczmera,
• Annalena Dietz,
• Andreas Boelke and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27

• used to create dicationic iodonium salts. The N-Me and N-Ph-iodonium-benzimidazolium salts 5av and 5aw were obtained in 47% and 36% yield, respectively. The introduction of additional ortho-methyl groups resulted in the formation of the σ-hole-protected N-substituted salts 5ax–az in up to 97% yield

• TsNH2 in combination with NaOCl as an oxidant was investigated next. Under these conditions, the N-Me salts 5ax and 12 gave the desired products 14a and 14b in 55% and 26% yield, respectively. The corresponding N-Ph- and N-Mes-derivatives 5ay and 5az failed to give products 14c and 14d and only