Direct C2–H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

• Martina Mamone,
• Giuseppe Gentile,
• Jacopo Dosso,
• Maurizio Prato and
• Giacomo Filippini

Beilstein J. Org. Chem. 2023, 19, 575–581, doi:10.3762/bjoc.19.42

• both UV–vis and nuclear magnetic resonance (NMR) spectroscopy [29]. In particular, the optical absorption spectra of substrate 2a (green dotted line), DABCO (red dotted line), and the solution containing both 2a and DABCO (blue line) were recorded in acetonitrile (Figure 2). Specifically, it was

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

• cyclopropanation. Reaction conditions: alkene (0.15 mmol), diazo compound 5 (0.1 mmol), CuI (1 mol %), dry toluene, 111 °C, Ar atmosphere. aYields refer to isolated products; bdr ratio determined by 19F NMR spectroscopy. Scope of the cyclopropanation. Reaction conditions: alkene (0.15 mmol), diazo compound 5 (0.1

• mmol), CuI (1 mol %), dry toluene, 111 °C, Ar atmosphere. aYields refer to isolated products; bdr ratio determined by 19F NMR spectroscopy. Addition of CuI to the diazo compound 5. Possible addition of styrene to Int2 yielding Int4_1 and Int4_2 through Int3_1 and Int3_2. Possible addition of styrene to

Mechanochemical solid state synthesis of copper(I)/NHC complexes with K₃PO₄

• Ina Remy-Speckmann,
• Birte M. Zimmermann,
• Mahadeb Gorai,
• Martin Lerch and
• Johannes F. Teichert

Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34

• synthesized via the mechanochemical route is isolated as a CH2Cl2 adduct (5/CH2Cl2 = 1:1) as confirmed by NMR spectroscopy and elemental analysis. If complex 5 is formed via the liquid state synthesis [48][49], also a CH2Cl2 adduct is isolated, albeit with a 5/CH2Cl2 ratio of 2:1. In order to demonstrate the

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

• esters, lactones, and carbonates with HBpin under microwave irradiation (Scheme 13) [57]. When HBpin and boric acid were reacted together, BH3-coordinated HBpin and O(Bpin)2 were detected by 11B NMR spectroscopy. Supported by computational analysis and single-turnover experiments, the reaction was

Investigation of cationic ring-opening polymerization of 2-oxazolines in the “green” solvent dihydrolevoglucosenone

• Solomiia Borova and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2023, 19, 217–230, doi:10.3762/bjoc.19.21

• kinetic study of the polymerization was monitored by 1H NMR spectroscopy analysis. NMR spectra were recorded on a Fourier 300 spectrometer (1H; 300.12 MHz and 13C (1H); 75.48 MHz; Bruker Biospin; Rheinstetten, Germany) at a temperature of 298 K and evaluated using the MestReNova V.6.0.2.-5475 software

• full monomer conversion. Monomer conversion was monitored by 1H NMR spectroscopy. After complete monomer consumption, the reaction was terminated by adding 3.0 equiv of water and left to react overnight at 45 °C. The polymer was purified by precipitation from cold diethyl ether (Et2O) or direct

• polymerization at 90 °C. The initial monomer concentration was kept at 3 M and [M]0/[I]0 was kept at 50 for the initial kinetic investigation. The monomer conversion was followed by 1H NMR spectroscopy and plotted in the common semi-logarithmic kinetic plots (Figure 2). For the majority of initiators, the

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• Humulus lupulus, and the structures of both compounds were elucidated by 1H NMR spectroscopy and catalytic hydrogenation, yielding the same compound selinane in both cases [54]. Both compounds were later also isolated from Cannabis sativa [55]. Unfortunately, no optical rotations were given in these

• was determined by NMR spectroscopy and verified by the acid-catalysed conversion into δ-selinene (26) (Scheme 9A) [72]. The same compound 18 was also reported from the closely related alga Laurencia nipponica [73] and from lime oil (Citrus aurantifolia) [74]. Fully assigned 1H and 13C NMR data were

• assignments and even error propagation, and shows the importance of structure elucidation by classical methods, i.e., isolation and compound characterisation by NMR spectroscopy and determination of optical rotation. Compound 51 can be generated biosynthetically from I3a through 1,2-methyl migration to I3b

Total synthesis of insect sex pheromones: recent improvements based on iron-mediated cross-coupling chemistry

• Eric Gayon,
• Guillaume Lefèvre,
• Olivier Guerret,
• Adrien Tintar and
• Pablo Chourreu

Beilstein J. Org. Chem. 2023, 19, 158–166, doi:10.3762/bjoc.19.15

• RMgX:EtOMgX ratios, minor species possibly featuring alkoxide stabilized ferrous [FeII]-OEt intermediates were observed by paramagnetic 1H NMR spectroscopy. In line with this result, Fleischer and Lefèvre also recently demonstrated that the anionic thiolate leaving group EtS– released in Fukuyama cross

Synthesis and characterisation of new antimalarial fluorinated triazolopyrazine compounds

• Kah Yean Lum,
• Jonathan M. White,
• Daniel J. G. Johnson,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2023, 19, 107–114, doi:10.3762/bjoc.19.11

• (0.1% TFA) were held for the first 1 min, followed by a linear gradient to 100% MeOH (0.1% TFA) over 59 min, all at a flow rate of 9 mL/min. Sixty fractions (60 × 1 min) were collected from the start of the HPLC run. Fractions containing UV-active material were analysed by 1H NMR spectroscopy and LCMS

Improving the accuracy of ³¹P NMR chemical shift calculations by use of scaling methods

• William H. Hersh and
• Tsz-Yeung Chan

Beilstein J. Org. Chem. 2023, 19, 36–56, doi:10.3762/bjoc.19.4

• development nor in the energy benchmarks that are used. Instead, we looked at recent work, mostly on 13C NMR spectroscopy, for recommendations [7][90][91][96][97][98]. Results are collected in Table 4 for the chemical shifts for compounds 1a, 8, and 32, scaled using only the first and last points for the

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

• Alexios I. Vicatos,
• Zakiena Hoossen and
• Mino R. Caira

Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184

• 1H NMR spectroscopy. Subsequent measurements of the aqueous solubilities of the four complexes confirmed significant solubility improvements effected by encapsulation of the steroids within the CDs, yielding solubility enhancement factors for BES and PRO in the approximate range 5–20. Keywords

• derivatised CDs containing BES and PRO, thus confirming the sustained interest in this approach and its significance in drug delivery. Previous studies of the complexation of BES, PRO and related compounds by CDs in the solution phase have typically reported the use of NMR spectroscopy to investigate complex

• γ-CD·BES, which diffracted very weakly. Host–guest stoichiometric determination by 1H NMR spectroscopy The host–guest stoichiometries for these complexes were unambiguously determined via solution-state 1H NMR spectroscopy, the samples for the analyses being the complex product materials produced

Synthetic study toward tridachiapyrone B

• Morgan Cormier,
• Florian Hernvann and
• Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

• isolated in 41% yield [43] while cyclohexenone 18 was not observed in the crude reaction mixture (as analyzed by 1H NMR spectroscopy). Even though the mechanism was not investigated, the presence of oxygen during the rearrangement step was suspected to account for the oxidation of the enolate intermediate

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• a tertiary alcohol. The structures of compounds (+)-1 and (+)-2 were elucidated through a combination of HRMS and NMR spectroscopy, while the relative configuration of each compound was established through nuclear Overhauser effect (NOE) correlations. Additionally, the absolute configuration of each

Solid-phase total synthesis and structural confirmation of antimicrobial longicatenamide A

• Takumi Matsumoto,
• Takefumi Kuranaga,
• Yuto Taniguchi,
• Weicheng Wang and
• Hideaki Kakeya

Beilstein J. Org. Chem. 2022, 18, 1560–1566, doi:10.3762/bjoc.18.166

• synthesized compound 1 agreed with those of natural 1. At this stage the confirmation of the identity of natural and synthesized compounds by structural determination using NMR spectroscopy is often difficult because the NMR spectra of peptidic products vary depending on the conditions in the NMR tube [25][26

Efficient synthesis of aziridinecyclooctanediol and 3-aminocyclooctanetriol

• Emine Salamci and
• Ayse Kilic Lafzi

Beilstein J. Org. Chem. 2022, 18, 1539–1543, doi:10.3762/bjoc.18.163

• in 90% yield. Thus, the dimesylate 8, which is one of the most relevant precursors for the synthesis of aminocyclitols, was synthesized from the diol 7. The structure of compound 8 was assigned on the basis of NMR spectroscopy. In the 1H NMR spectrum, we observed that methyl signals of the mesylate

• the diazide 9 (Scheme 2). However, the product was determined to be the azidomesylate 10 instead of the expected diazide 9 based on NMR spectroscopy. The position of the azide functionality in 10 was determined from its COSY spectrum. The diagonal peak at 3.97 ppm has cross peaks with the protons

• a positive NOE clearly indicates that the protons H-2/H-7 should have a cis configuration relative to the protons H-1/H-8. Finally, benzyl deprotection with BCl3 of 14 afforded the product 16 in 84% yield. The structure of 16 was assigned on the basis of NMR spectroscopy. Conclusion In summary, we

One-pot synthesis of 2-arylated and 2-alkylated benzoxazoles and benzimidazoles based on triphenylbismuth dichloride-promoted desulfurization of thioamides

• Arisu Koyanagi,
• Yuki Murata,
• Shiori Hayakawa,
• Mio Matsumura and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 1479–1487, doi:10.3762/bjoc.18.155

• by 1H NMR spectroscopy, phenylbenzimidoyl chloride (17) was observed to be generated (Scheme 3a) (see Supporting Information File 1 for details). When o-aminophenol (1a) was reacted with 17 [41] in a 1:2 ratio, product 8a and diphenylbenzamidine (18) were obtained in 81% and 86% yields, respectively

Synthesis of the biologically important dideuterium-labelled adenosine triphosphate analogue ApppI(d₂)

• Petri A. Turhanen

Beilstein J. Org. Chem. 2022, 18, 1466–1470, doi:10.3762/bjoc.18.153

• (d2) opens possibilities to quantitative measurements of ApppI in biological samples by mass spectrometry. The synthesized target compound ApppI(d2) was purified by high-performance counter current chromatography and characterized by 1H, 13C, and 31P NMR spectroscopy as well as high-resolution mass

Sinensiols H–J, three new lignan derivatives from Selaginella sinensis (Desv.) Spring

• Qinfeng Zhu,
• Beibei Gao,
• Qian Chen,
• Tiantian Luo,
• Guobo Xu and
• Shanggao Liao

Beilstein J. Org. Chem. 2022, 18, 1410–1415, doi:10.3762/bjoc.18.146

• basis of 1D and 2D NMR spectroscopy as well as high-resolution mass spectrometry. The absolute configuration of 1 was established by ECD calculation. Compounds 2 and 3 represent rare examples of naturally occurring 9,9'-bisnorlignans. All the isolated compounds were assayed for their inhibitory effects

Cyclodextrin-based Schiff base pro-fragrances: Synthesis and release studies

• Attila Palágyi,
• Jindřich Jindřich,
• Juraj Dian and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2022, 18, 1346–1354, doi:10.3762/bjoc.18.140

• – cinnamaldehyde, cyclamen aldehyde, lilial, benzaldehyde, anisaldehyde, vanillin, hexanal, heptanal, citral, and 5-methylfurfural. Subsequently, the rate of release of the volatile compound from selected pro-fragrances, as a function of the environment (solvent, pH), was studied by 1H NMR spectroscopy (for

• stability towards hydrolysis. Kinetic studies of the imine hydrolysis by NMR For the kinetic studies of the hydrolysis of imino-CDs, we selected the pro-fragrance 3d made from the most common aldehyde – benzaldehyde. The release of the benzaldehyde (2d) was studied by 1H NMR spectroscopy. Aqueous 0.1 M

• phosphate buffer solutions of pH 1.08, 2.00, 3.00, 4.00, 5.00, 6.00, 7.00, 8.00, 9.00, 10.00 11.00, 12.00, and 12.80 were prepared (see Experimental section) using deuterium oxide instead of water to facilitate NMR spectroscopy experiments. Because of the low solubility of the pro-fragrance in water, it had

Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

• Almaz A. Zagidullin,
• Farida F. Akhmatkhanova,
• Mikhail N. Khrizanforov,
• Robert R. Fayzullin,
• Tatiana P. Gerasimova,
• Ilya A. Bezkishko and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139

• bromides from one starting aryl aldehyde. Diethyl phosphite was allowed to react with appropriately substituted benzaldehydes in THF for 48 hours at 25 °C to afford diethyl (hydroxy(aryl)methyl)phosphonates 1, which were detected by 31P NMR spectroscopy in THF (21.4 ppm for 1a, 21.0 ppm for 1b, and 21.5

• confirmed by 31P, 1H, and 13C NMR spectroscopy. The 31P{1H} NMR spectra of phosphonium bromides 6 showed a singlet at about 40 ppm, which is typical for phosphonium salts. The 13C{1H} NMR spectra consisted of a doublet at about 20 ppm, corresponding to the carbon atom C1, which is characteristic for the sp3

• (Scheme 3). The structure of 3,4,5-triaryl-1,2-diphosphaferrocene 8b was confirmed by 31P, 1H, and 13C NMR spectroscopy. The 31P{1H} NMR spectrum of 8b showed a singlet at about −10 ppm, shifted upfield by about 210 ppm in comparison to the starting 1,2-diphospholide anion 7b. In the 1H NMR spectra

B–N/B–H Transborylation: borane-catalysed nitrile hydroboration

• Filip Meger,
• Alexander C. W. Kwok,
• Franziska Gilch,
• Dominic R. Willcox,
• Alex J. Hendy,
• Kieran Nicholson,
• Andrew D. Bage,
• Thomas Langer,
• Thomas A. Hunt and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2022, 18, 1332–1337, doi:10.3762/bjoc.18.138

• mol %), Ar atm., 60 °C, 18 h, unless otherwise noted. Isolated yields are reported. a1.0 mmol scale. bHBpin (5.5 equiv). c80 °C. d40 °C. a) Proposed mechanism; b) H-B-9-BBN-catalysed heptanenitrile hydroboration (yield determined by 1H NMR spectroscopy using 1,3,5-trimethoxybenzene as an internal

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

• Merve Karaman,
• Abhishek Kumar Gupta,
• Subeesh Madayanad Suresh,
• Tomas Matulaitis,
• Lorenzo Mardegan,
• Daniel Tordera,
• Henk J. Bolink,
• Sen Wu,
• Stuart Warriner,
• Ifor D. Samuel and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

• synthetic strategy, which itself was synthesized from Br-DiKTa [28] following a Buchwald–Hartwig coupling. Details of the synthesis are found in Supporting Information File 1. The identity and purity of the molecules were verified using a combination of 1H and 13C NMR spectroscopy, high resolution mass

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

• nitrogen intermediate, see Scheme S1 in Supporting Information File 1). In any case, the N7-ferrocenoylation of adenine anion 3 is a viable process, as demonstrated by the 1H NMR spectroscopy evidence (see above), and by the isolation of the N7-ferrocenoylated product. We have continued our study with an

Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation

• Ashish Kumar Mazumdar,
• Gyana Prakash Nanda,
• Nisha Yadav,
• Upasana Deori,
• Upasha Acharyya,
• Bahadur Sk and
• Pachaiyappan Rajamalli

Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122

• Supporting Information File 1. Both compounds were further purified by temperature-gradient vacuum sublimation and characterized by 1H and 13C NMR spectroscopy (Figures S9–S12, Supporting Information File 1) as well as high-resolution mass spectrometry. Photophysical studies and DFT calculations The UV–vis

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

• . All products were fully characterized by HRMS as well as 1H and 13C NMR spectroscopy. Thus, this approach is valuable for promoting the synthesis of N-phenyl-1H-indazoles in a higher yield than that reported in the literature using copper catalysis and the same substrates. This study also prompted the

• of CuI, only the product 2i’ or 4i’, respectively, was detected by 1H NMR spectroscopy in the crude reaction mixture (Figures S7–S10 and Figures S11–S14, respectively, Supporting Information File 1). This result shows that o-fluorinated arylhydrazones may be suitable as starting materials to prepare

• determination of the amount of product and/or starting material in the crude mixture by 1H NMR spectroscopy was conducted by adding 1 equiv of trichloroethylene as calibration compound after diluting the crude mixture in CDCl3. The amounts were estimated by comparing the integral value of the product C3–H

Facile and diastereoselective arylation of the privileged 1,4-dihydroisoquinolin-3(2H)-one scaffold

• Dmitry Dar’in,
• Grigory Kantin,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1070–1078, doi:10.3762/bjoc.18.109

• substituent and an N-alkyl group (considering that N-aryl nitrophenyl-substituted compound 10o was obtained in a respectable 91% yield). The structures of compounds 10a–s were unequivocally confirmed by 1H and 13C NMR spectroscopy (paying a particular attention to the appearance of the C=N2 signal in the

• ). Using more reactive (electron-rich) arenes results in lower diastereoselectivity and regiospecificity of the reaction (cf. 9q, 9v, and 9w). The structure and the initially anticipated trans-configuration of the products 9 was unequivocally confirmed by 1H and 13C NMR spectroscopy as well as, in the case