Functional characterisation of twelve terpene synthases from actinobacteria

• Anuj K. Chhalodia,
• Houchao Xu,
• Georges B. Tabekoueng,
• Binbin Gu,
• Kizerbo A. Taizoumbe,
• Lukas Lauterbach and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1386–1398, doi:10.3762/bjoc.19.100

• structures were elucidated by NMR spectroscopy, resulting in the discovery of the first terpene synthases for (+)-δ-cadinol and (+)-α-cadinene, besides the first two bacterial (−)-amorpha-4,11-diene synthases. For other terpene synthases with functions reported from bacteria before the products were

• ; biosynthesis; enzymes; NMR spectroscopy; terpenes; Introduction Terpene synthases are remarkable enzymes that can convert acyclic and achiral oligoprenyl pyrophosphates into terpene hydrocarbons or alcohols of high structural complexity. These enzymatic reactions are initiated by ionisation of the substrate

• accepted. A preparative scale incubation of FPP (80 mg, 185 μmol) allowed for the isolation of 10 (5.5 mg, 25 μmol, 14%) for structure elucidation through NMR spectroscopy (Table S2, Figures S3–S10, Supporting Information File 1), confirming the structure of δ-cadinol. The optical rotation of [α]D25

Consecutive four-component synthesis of trisubstituted 3-iodoindoles by an alkynylation–cyclization–iodination–alkylation sequence

• Nadia Ledermann,
• Alae-Eddine Moubsit and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2023, 19, 1379–1385, doi:10.3762/bjoc.19.99

• compounds 5 in yields between 11–69% after chromatographic workup. The structures of the products were unambiguously confirmed by 1H and 13C NMR spectroscopy, as well as by mass spectrometry. Assuming that four new bonds are being formed in this one-pot process, the range of yield from 11 to 69% (after

• -trisubstitued indoles 8 in good yield (Scheme 4). The 1,2,3-trisubstitued indoles 8 were unambiguously confirmed by 1H and 13C NMR spectroscopy, as well as by mass spectrometry and elemental analysis. Miura et al. could show that 1-alkyl-2,3-diarylindoles constitute a class of blue-emissive indole derivatives

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• , and 1H/13C NMR spectroscopy. Proton NMR shows a complicated set of overlapping multiplets indicating that the reaction results in the formation of various isomers (rotamers) which are different by relative orientation of the benzoguanidine donor moieties with respect to each other (Figure 2, see

Selective construction of dispiro[indoline-3,2'-quinoline-3',3''-indoline] and dispiro[indoline-3,2'-pyrrole-3',3''-indoline] via three-component reaction

• Ziying Xiao,
• Fengshun Xu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1234–1242, doi:10.3762/bjoc.19.91

• structures of the obtained dispiro compounds 3a–m were fully characterized by IR, HRMS, 1H and 13C NMR spectroscopy. Because of the three chiral carbon atoms in the product, several diastereomers might be formed in the reaction. However, TLC monitoring and 1H NMR spectra of the crude products clearly

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

• catalysts in an acetonitrile/water mixture [46]. They used combinations of deuterated solvents and 1H NMR spectroscopy to confirm that water was the main source of the protons for the regeneration. Furthermore, they successfully replaced ruthenium photosensitizers with organic dyes so that the system used

Cyanothioacetamides as a synthetic platform for the synthesis of aminopyrazole derivatives

• Valeriy O. Filimonov,
• Alexandra I. Topchiy,
• Vladimir G. Ilkin,
• Tetyana V. Beryozkina and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2023, 19, 1191–1197, doi:10.3762/bjoc.19.87

• pyrazoles has been thus synthesized. The structure of the reaction products was studied using NMR spectroscopy and mass spectrometry and confirmed by X-ray diffraction analysis. Keywords: aminopyrazoles; 2-cyanothioacetamides; enamines; hydrazines; Introduction Compounds containing a pyrazole cycle

• -diaminopyrazoles 4a–c (Scheme 2). The structures of compounds 4a–c were confirmed by 1H and 13C NMR spectroscopy data, as well as high-resolution mass spectrometry (HRMS). Compound 4a was previously obtained by another method [18]. The spectral characteristics of diaminopyrazole 4a reported in [18] correspond to

• group during the reaction. The structures of compounds 5a–e were confirmed by 1H and 13C NMR spectroscopy and HRMS, as well as X-ray diffraction analysis of a single crystal of compound 5b. The involvement of arylhydrazines 3b,c in the reaction with enamines 2a–d similarly leads to the formation of 1

Synthesis of imidazo[4,5-e][1,3]thiazino[2,3-c][1,2,4]triazines via a base-induced rearrangement of functionalized imidazo[4,5-e]thiazolo[2,3-c][1,2,4]triazines

• Dmitry B. Vinogradov,
• Alexei N. Izmest’ev,
• Angelina N. Kravchenko,
• Yuri A. Strelenko and
• Galina A. Gazieva

Beilstein J. Org. Chem. 2023, 19, 1047–1054, doi:10.3762/bjoc.19.80

• . However, we also detected by 1H NMR spectroscopy the formation of other minor products, presumably derivatives of a new heterocyclic system, imidazo[4,5-e][1,3]thiazino[2,3-c][1,2,4]triazines 5a,b (Scheme 2). To prepare the new compounds 5, the solvent, amount of KOH, reaction time, and temperature were

• with excess hydrochloric acid and further evaporation of the solvent at 40 °C led to decomposition products, two of which were isolated and characterized by NMR spectroscopy including 2D experiments and HRMS data. The target acids 5k,m were obtained using equivalent amounts of HCl at room temperature

• in the thiazine ring leads to the cleavage of the triazine C–N bond. Further proton transfer gives product 9. The structures of the synthesized compounds 3a,b,j and 5a–k,m were confirmed by IR, 1H and 13C NMR spectroscopy, and high-resolution mass spectrometry. the potassium salts 3c–i,k,m were

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

• cucurbit[6]uril (TMeQ[6]) and 1,2-bis(4-pyridyl)ethene (G) were used to construct a supramolecular fluorescent probe G@TMeQ[6]. The host–guest interaction between TMeQ[6] and G was investigated using 1H NMR spectroscopy, single-crystal X-ray diffraction and various experimental techniques. The results show

• unwanted data point, the data was analyzed using the independent model Launch Nano analysis software. 1H NMR spectroscopy The host–guest interaction between G and TMeQ[6] and the interaction mode between G@TMeQ[6] fluorescent probe and Hg2+ ion were studied by 1H NMR titration spectroscopy. All 1H NMR

• spectroscopy data were recorded on a JEOL JNM-ECZ400s spectrometer in D2O at 293.15 K [42]. X-ray crystallography Using single-crystal X-ray diffraction has been previously described in the literature [43]. The main crystal structure parameters are recorded in Table 2. In addition, CCDC-2225763 contains the

Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Mikhail E. Minyaev and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58

• result, both products could be isolated and characterized using 1H, 13C NMR spectroscopy and mass spectrometry. Moreover, the structure of product 11a was also confirmed by single-crystal X-ray diffraction analysis. It might be noted that precipitated crystals of 11a contained two polymorph modifications

• 11g–j were confirmed by 1H, 13C NMR spectroscopy and high-resolution mass spectrometry. In the 1H NMR spectra of the products, characteristic singlets corresponding to the protons of the dihydropyranone fragment in the region δ 5.3–5.4 ppm and the protons of the hydroxy group in the region δ 5.4–5.5

Bromination of endo-7-norbornene derivatives revisited: failure of a computational NMR method in elucidating the configuration of an organic structure

• Demet Demirci Gültekin,
• Arif Daştan,
• Yavuz Taşkesenligil,
• Cavit Kazaz,
• Yunus Zorlu and
• Metin Balci

Beilstein J. Org. Chem. 2023, 19, 764–770, doi:10.3762/bjoc.19.56

• temperatures yielding mixtures of addition products. The structural elucidations of the formed compounds were achieved by NMR spectroscopy. Particularly, the γ-gauche effect and long-range couplings were instrumental in assigning the stereochemistry of the adducts. However, in a recent paper, Novitskiy and

• erroneous mechanistic pathway. Keywords: bromination; computational NMR; γ-gauche effect; NMR; NOE-Diff experiments; Introduction Nuclear magnetic resonance (NMR) spectroscopy is one of the most important analytical tools used to determine the structure of organic compounds. NMR not only confirms the

Synthesis of imidazo[1,2-a]pyridine-containing peptidomimetics by tandem of Groebke–Blackburn–Bienaymé and Ugi reactions

• Oleksandr V. Kolomiiets,
• Alexander V. Tsygankov,
• Maryna N. Kornet,
• Aleksander A. Brazhko,
• Vladimir I. Musatov and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2023, 19, 727–735, doi:10.3762/bjoc.19.53

• target reaction product was observed by 1H NMR spectroscopy of the crude reaction mixture. It was found that in the case of Table 2, entry 6, the ratio of product 9b to acid 8b was approximately 1:3. The obtained results show that for the synthesis of new compounds containing precisely substituted

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

• through a butadiyne linker and aryl–C≡C–DMAN conjugation paths. A comprehensive study by X-ray diffraction, NMR spectroscopy and cyclic voltammetry revealed that the “butadiyne pathway” is realized in cases where the aryl substituent is p-methoxyphenyl, phenyl or p-(trifluoromethyl)phenyl. Oligomers 5

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