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

• the ethyl acetate fraction (Figure 1). The structures of known compounds 5–7 were identified based on 1H and 13C NMR data [2][3][10]. Breynin J (1) was isolated as an amorphous, colorless powder. The HRESIMS spectrum exhibited a sodium adduct ion peak at m/z 1107.3177, consistent with a molecular

• . In addition, signals corresponding to a p-hydroxybenzoate group [δH 8.02 (d, J = 8.9 Hz, 2H, H-21, 25), 6.94 (d, J = 8.9 Hz, 2H, H-22, 24)] were observed. The 13C NMR spectrum (Table 1) suggested the presence of a breynogenin-α-S-oxide moiety, similar to that in breynins B, D, G, and I [2], with the

• aglycone of 2 also consisted of a breynogenin-S-oxide moiety. However, a comparison of the 1H and 13C NMR data for the aglycones of 1 and 2 revealed markedly different tetrahydrothiophene signals [for 2, δC 61.7 (C-2), 87.4 (C-3), 39.9 (C-4), 62.3 (C-17)] (Table 1). According to previous literature [2

Secondary metabolites of Diaporthe cameroonensis, isolated from the Cameroonian medicinal plant Trema guineensis

• Bel Youssouf G. Mountessou,
• Élodie Gisèle M. Anoumedem,
• Blondelle M. Kemkuignou,
• Yasmina Marin-Felix,
• Frank Surup,
• Marc Stadler and
• Simeon F. Kouam

Beilstein J. Org. Chem. 2023, 19, 1555–1561, doi:10.3762/bjoc.19.112

• (d, 2.0 Hz, 1H each), and at δH 7.57 and 6.62 (d, 1.0 Hz, 1H each), in addition to a singlet signal at δH 2.71 (s, CH3, 3H). The alternariol skeleton was further confirmed by the 13C NMR and HSQC spectra (Figures S10 and S11 in Supporting Information File 1), in conjunction with the HMBC spectrum

• overlapping at δH 2.28 due to two acetyl groups, which showed strong HMBC cross peaks with the carbonyl carbon signals at δH 169.0. The structure of 2 was fully assigned by using the 13C NMR spectrum which displayed sixteen carbon signals sorted into three methyl signals of which two overlapping ones at δC

• /USA) 500 MHz Avance III spectrometer with a BBFO (plus) Smart Probe (1H NMR: 500 MHz and 13C NMR: 125 MHz). Chemical shifts (δ) were reported in ppm using tetramethylsilane (TMS) (Sigma-Aldrich) as an internal standard, while coupling constants (J) were measured in hertz (Hz). Optical rotations were

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

• Tzu-Yu Huang,
• Mario Djugovski,
• Sweta Adhikari,
• Destinee L. Manning and
• Sudeshna Roy

Beilstein J. Org. Chem. 2023, 19, 1545–1554, doi:10.3762/bjoc.19.111

• . Proposed mechanism. Scale-up experiment. Optimization of reaction conditions.a Supporting Information Supporting Information File 2: General information, experimental procedures for all the substrates and intermediates, characterization data, and NMR spectra (1H, 19F, and 13C NMR). Funding Research

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

• -Hydroxymethylfurfurylidene)-2-thioxothiazolidin-4-one (3j). ochre yellow solid obtained after 1 h at 60 °C in 36% yield (two-step yield). Mp 149 °C; 1H NMR (400 MHz, DMSO-d6) δ (ppm) 4.49 (s, 2H), 5.52 (br s, 1H, OH), 6.58 (d, J = 3.6 Hz, 1H), 7.11 (d, J = 3.6 Hz, 1H), 7.44 (s, 1H, =CH), 13.62 (br s, 1H, NH); 13C NMR (100

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

• ) ppm; 13C NMR (100 MHz, DMSO-d6, T = 298 K) δ 152.0, 124.6, 123.3, 102.6, 43.7, 37.1, 30.7, 25.8, 22.8 ppm. 1:1 Complex of R[4]A with diethylamine: 68% yield; white solid; 1H NMR (400 MHz, DMSO-d6, T = 298 K) δ 7.16 (s, 4H, PhCH), 6.10 (s, 4H, PhCH), 5.6–3.6 (br s, 8H, OH), 4.34 (t, J = 7.70 Hz, 4H, CH

• , 4H, PhH), 4.43 (m, 4H, CH), 3.42 (q, J = 6.97 Hz, 2H, NCH2CH3), 3.41 (q, J = 6.97 Hz, 2H, NCH2CH3), 2.08 (m, 8H, CH2), 1.47 (m, 4H, CH), 1.24 (m, 3H, NCH2CH3), 0.97 (t, J = 6.60 Hz, 24H, CH3), 0.22 (br t, 3H, NCH2CH3) ppm; 13C NMR (100 MHz, DMSO-d6, T = 298 K) δ 151.8, 124.9, 123.2, 102.5, 42.9, 42.7

• , 2H, N(CH2)2(CH2)2), 1.49 (m, 4H, CH), 0.99 (t, J = 6.24 Hz, 24H, CH3), −0.7 (m, 4H, N(CH2)2(CH2)2) ppm; 13C NMR (100 MHz, DMSO-d6, T = 298 K) δ 152.0, 124.3 123.3, 102.7, 45.7, 42.5, 31.6, 25.7, 24.6, 22.7 ppm. 1:1 Complex of R[4]A with piperidine: 78% yield; white solid; 1H NMR (400 MHz, DMSO-d6, T

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• of enones 2a,e,n with an excess (5 equiv) of AlBr3 or AlCl3 in CH2Cl2 solution at room temperature for 3 days afforded complex mixtures of compounds. Then, the protonation of compounds 1 and 2 in TfOH was investigated by means of NMR spectroscopy. According to the 1H, 13C, and 19F NMR data, hydroxy

• to the 13C NMR spectra, the largest downfield shift was observed for the carbonyl carbon С1, with ∆δ = 17.7–21.1 ppm, showing a substantial degree of protonation of the carbonyl group in TfOH. The tendencies are the same for the protonation of enones 2a,c,d,m leading to cations Ba,c,d,m (Table 2

• ). Thus, in the 1H NMR spectra, downfield shifts of vinyl protons H2 and H3 upon protonation were 0.50–0.61 and 0.41–0.54 ppm, respectively. In the 13C NMR spectra, ∆δ values for carbons С1 and С3 were 12.7–21.3 and 6.0–13.4 ppm, respectively. The NMR data revealed that the positive charge in the O

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

• by the positioning of the ethyl groups in the products 2 and 3. Notably, the findings correspond to those made with the native substrate 2-Me-GPP in feeding experiments with (1-13C)-1-deoxyxylulose [30]. Conclusion In the present study we have investigated two aspects of 2-methylisoborneol

• ppm) for 1H NMR and the 13C signal of C6D6 (δ = 128.06 ppm) for 13C NMR [39]. Coupling constants are given in Hz. IR spectra were recorded on a Bruker α infrared spectrometer with a diamond ATR probehead. Peak intensities are given as s (strong), m (medium), w (weak) and br (broad). Optical rotations

• ; 13C NMR (126 MHz, D2O) δ 135.80 (Cq), 133.72 (Cq), 125.03 (d, 3JC,P = 8.5, CH), 124.26 (CH), 67.10 (d, 2JC,P = 5.6, CH2), 34.11 (CH2), 25.67 (CH2), 24.83 (CH3), 17.41 (CH3), 16.86 (CH3), 15.67 (CH3) ppm; 31P NMR (202 MHz, D2O) δ −7.90 (d, 2JP,P = 21.3), −10.40 (d, 2JP,P = 21.4) ppm; HRMS–TOF (m/z

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

• ), 7.23–7.26 (m, 1H), 7.46–7.54 (m, 5H); 13C NMR (150 MHz, CDCl3) δ 1.9 (Cquat), 32.4 (CH3), 106.7 (CH), 110.8 (CH), 111.5 (CH), 128.6 (Cquat), 129.3, 130.9, 131.5 (Cquat), 134.5 (Cquat), 143.5 (Cquat), 160.0 (Cquat); IR (cm−1) ν̃: 604 (w), 619 (w), 662 (w), 689 (s), 733 (m), 756 (s), 789 (m), 860 (w

Correction: Non-peptide compounds from Kronopolites svenhedini (Verhoeff) and their antitumor and iNOS inhibitory activities

• Yuan-Nan Yuan,
• Jin-Qiang Li,
• Hong-Bin Fang,
• Shao-Jun Xing,
• Yong-Ming Yan and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 1370–1371, doi:10.3762/bjoc.19.97

• HMBC correlations of H-2/C-1, C-3, C-4, C-8a, H-4/C-3, C-4a, C-5, C-8a, C-9, H-5/C-4, C-4a, C-6, C-7, C-8a, H-9/C-2, C-3, C-4, H-10/C-7, C-8, C-8a, H-11/C-6, and H-12/C-7. Table 1 provides the revised 1D 1H and 13C NMR data of compound 1. The structural revision of 1 also required recalculation of the

• compound 1 and key HMBC correlations. Recalculated and experimental ECD spectra of compound 1. Revised 1H (600 MHz) and 13C NMR (150 MHz) data of compound 1 (δ in ppm, J in Hz, methanol-d4).

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

• mineral oil with diethyl ether and dried prior to use. 5H-Benzo[d]benzo[4,5]imidazo[1,2-a]imidazole (benzoguanidine) was obtained according to the literature protocol [10] while 2,4,5,6-tetrafluoroisophthalonitrile was purchased from Fluorochem Ltd. and used as received. 1H and 13C{1H} NMR spectra were

• recorded using a Bruker AVIII HD 500 MHz NMR spectrometer. 1H NMR spectra (500.19 MHz) and 13C{1H} (125.79 MHz) were referenced to dichloromethane-d2 at δ 5.32 (13C, δ 53.84). All electrochemical experiments were performed using an Autolab PGSTAT 302N computer-controlled potentiostat. Cyclic voltammetry

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

• ) onto acyclic MBH alcohols 1a–f. Supporting Information Supporting Information File 69: Full experimental details and characterization data of all new compounds. Supporting Information File 70: 1H and 13C NMR and HRMS spectra of compounds. Acknowledgements We thank the Tunisian Chemical Society for

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

• , 1H, CH2), 2.46 (d, J = 16.0 Hz, 1H, CH2), 2.39 (d, J = 16.0 Hz, 1H, CH2), 2.37–2.34 (m, 2H, CH2), 1.30 (s, 3H, CH3), 1.15 (s, 3H, CH3), 0.76 (t, J = 7.2 Hz, 3H, CH3) ppm; 13C NMR (101 MHz, CDCl3) δ 193.0, 173.8, 171.9, 171.2, 155.6, 142.0, 141.8, 134.8, 134.1, 131.0, 129.3, 129.1, 128.8, 128.7, 128.6

• = 4.8 Hz, 1H, CH2), 4.43 (d, J = 5.2 Hz, 1H, CH2), 2.41 (d, J = 26.8 Hz, 1H, CH2), 2.40 (s, 3H, CH3), 2.21 (d, J = 18.4 Hz, 1H, CH2), 2.10 (s, 1H, CH3), 2.05 (s, 1H, CH2), 1.87 (d, J = 16.0 Hz, 1H, CH2), 1.00 (s, 3H, CH3), 0.99 (s, 3H, CH3) ppm; 13C NMR (101 MHz, CDCl3) δ 197.5, 181.6, 177.4, 177.2

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• copper(II) porphyrins 3–8. Finally, the structures of all newly synthesized benzo[f]chromeno[2,3-h]quinoxalinoporphyrins 3–16 and benzo[f]quinoxalinoporphyrin 17 were assigned on the basis of IR, 1H and 13C NMR, and HRMS data analysis. Photophysical characteristics The UV–vis spectra of the newly

• MHz) and 13C NMR (100 MHz) spectra were recorded in CDCl3 on a Jeol ECX-400P (400 MHz) NMR spectrometer. Chemical shifts are reported in δ scale in parts per million (ppm) relative to CDCl3 (δ = 7.26 ppm for 1H NMR and δ = 77.00 ppm for 13C NMR). The coupling constants are expressed as (J) and are

• ]chromeno[2,3-h]quinoxalinoporphyrin 3. Optimization of the reaction conditions for the synthesis of copper(II) benzo[f]chromeno[2,3-h]quinoxalinoporphyrin 3.a Supporting Information Supporting Information File 186: Characterization data, 1H and 13C NMR spectra of newly prepared porphyrin products

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

• -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

• upon addition of hydrochloric acid. This is probably due to the protonation of the dimethylamino moiety or/and that dimethylamine hydrochloride is a better leaving group than the free base. The structures of compounds 6a–f were confirmed by 1H and 13C NMR spectroscopy and HRMS, as well as X-ray

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

• unsaturation in its structure. The 1H, 13C NMR, and HSQC spectral data of compound 1 (Table 1) revealed the presence of forty-three carbon resonances sorted into eight methyl, fourteen methylenes (one olefinic), ten methine and eleven unprotonated carbon atoms. This includes three carbonyl carbons at δC 177.4

• (C-21), 175.0 (C-5'), and 172.4 (C-1') as well as four olefinic carbon signals at δC 156.7 (C-24), 136.3 (C-9), 135.2 (C-8), and 107.4 (C-31). The 1H and 13C NMR spectral data of compound 1 (Table 1) also revealed the presence of a sugar moiety through the presence of the characteristic anomeric

• and 13C NMR data (Table 1) of the sugar moiety with that reported for a related fungal lanostanoside, ganosinoside A [26] and other glycosidic moieties [27], it was confirmed to be a β-ᴅ-glucopyranosyl residue. The HMBC spectrum of compound 1 (Figure 2) also revealed key correlations from two

New one-pot synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones based on 5-aminopyrazoles and azlactones

• Vladislav Yu. Shuvalov,
• Ekaterina Yu. Vlasova,
• Tatyana Yu. Zheleznova and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2023, 19, 1155–1160, doi:10.3762/bjoc.19.83

• Information Supporting Information File 124: Experimental procedures, characterization data, and 1H and 13C NMR spectra for all new compounds. Funding This work was supported by the Russian Science Foundation (grant No. 22-13-00356).

Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light

• Damiano Diprima,
• Hannes Gemoets,
• Stefano Bonciolini and
• Koen Van Aken

Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82

• the addition of 1 equivalent of aromatic molecules to the standard solution using tetrahydrothiophene as the substrate. Supporting Information Supporting Information File 104: General procedures, product characterization, and copies of 1H NMR and 13C NMR spectra of compounds. Funding We are grateful

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

• 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

• characterized by their 1H and 13C NMR spectra. In the 1H NMR spectra, the doublets of the bridging hydrogen atom C(9a)H in compound 4 and C(10a)H in compound 5 are characteristic signals which allow to attribute the synthesized compounds to one of the two heterocyclic systems, i.e., imidazo[4,5-e]thiazolo[2,3-c

• closer location in structures 5 (Figure 3). In the downfield region of the 13C NMR spectra registered without proton decoupling for isomeric acids 4a and 5a, the carbon atom doublets of the carboxyl groups, carbonyl groups of thiazole (for 4a) or thiazine (for 5a) cycles, as well as multiplets of

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

• by 1H NMR, 13C NMR, and HRMS spectra (Experimental section). UV–vis absorption and fluorescence emission spectra The UV–vis absorption spectra of the compounds were studied (Figure 1 and Figure S29 in Supporting Information File 1). For the compounds without an oxidized PTZ unit, there are

• , J = 7.51 Hz, 2H), 6.85–6.88 (m, 2H), 6.77–6.80 (m, 2H), 6.08 (d, J = 8.13 Hz, 2H); 13C NMR (CDCl3, 125 MHz) δ 162.9, 158.1, 151.9, 142.6, 138.2, 138.2, 130.8, 130.3, 128.0, 127.6, 124.6, 123.5, 121.1, 117.5, 116.4, 111.8; HRMS–ESI (m/z): [M + H]+ calcd for C30H17FN2O2S, 489.0995; found, 489.1072

• ) δ 8.87 (d, J = 7.63 Hz, 1H), 8.70 (d, J = 7.13 Hz, 1H), 8.59 (d, J = 8.38 Hz, 1H), 7.99 (d, J = 7.63 Hz, 1H), 7.76–7.80 (m, 1H), 7.57–7.61 (m, 2H), 7.52 (d, J = 7.38 Hz, 1H), 7.35 (d, J = 7.25 Hz, 2H), 7.11 (d, J = 7.50 Hz, 2H), 6.77–6.87 (m, 4H), 6.09 (d, J = 7.76 Hz, 2H); 13C NMR (CDCl3, 125 MHz

Five new sesquiterpenoids from agarwood of Aquilaria sinensis

• Hong Zhou,
• Xu-Yang Li,
• Hong-Bin Fang,
• He-Zhong Jiang and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 998–1007, doi:10.3762/bjoc.19.75

• , 273.1461), 13C NMR, and DEPT spectra, indicating 5 degrees of unsaturation. The 1H NMR spectrum of 1 (Table 1) shows one methyl group at δH 1.16 (s, 3H), two olefinic protons [δH 5.05 (d, J = 1.4 Hz, 1H), δH 4.05 (d, J = 1.4 Hz, 1H)], and an oxygenated methylene at δH 4.06 (s, 2H). The 13C NMR and DEPT

• 259.1671 [M + Na]+ (calcd 259.1669). The 13C NMR and DEPT spectra (Table 1) of 2 indicate 4 degrees of unsaturation. Compound 2 is similar in structure to 1 by analysis of their NMR data. There are two differences between 2 and 1. One is that at C-4 in 2 a methyl group is attached instead of a carboxyl

• 2 was eventually clarified to be 7S,8R,10S, and it was named aquisinenoid G. Compound 3 was isolated as pale yellow gum, and its molecular formula was determined to be C15H24O3 based on its HRESIMS m/z 275.1622 [M + Na]+ (calcd for C15H24O3Na, 275.1618), 13C NMR and DEPT spectra (Table 2

Synthesis of tetrahydrofuro[3,2-c]pyridines via Pictet–Spengler reaction

• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2023, 19, 991–997, doi:10.3762/bjoc.19.74

• . Reactivity of tetrahydrofuro[3,2-c]pyridine 4a. Optimization of reaction conditionsa. Supporting Information Supporting Information File 47: Experimental procedures, characterization data, copies of 1H and 13C NMR spectra, HRMS of new compounds, and X-ray crystallography data. Supporting Information File 48

The unique reactivity of 5,6-unsubstituted 1,4-dihydropyridine in the Huisgen 1,4-diploar cycloaddition and formal [2 + 2] cycloaddition

• Xiu-Yu Chen,
• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 982–990, doi:10.3762/bjoc.19.73

• temperature for two hours. After removing the solvent by rotatory evaporation at reduced pressure, the residue was subjected to column chromatography with petroleum ether and ethyl acetate (v/v = 5:1) as eluent to give the pure product for analysis. Trimethyl 4-benzyl-3-methyl-1-phenyl-4,4a,13b,13c-tetrahydro

• Hz, 1H, CH), 2.44 (s, 3H, CH3) ppm; 13C NMR (100 MHz, CDCl3) δ 168.7, 166.2, 164.9, 150.2, 146.1, 145.7, 138.7, 129.3, 128.8, 128.1, 128.0, 127.8, 127.5, 127.3, 127.0, 126.3, 126.1, 125.1, 124.7, 124.6, 106.3, 104.6, 102.8, 61.3, 57.6, 56.0, 53.0, 51.6, 50.0, 44.8, 39.5, 17.9 ppm. IR (KBr) ν: 3732

• ), 7.13–7.10 (m, 2H, ArH) 4.86 (d, J = 15.2 Hz, 1H, CH2), 4.59 (s, 1H, CH), 4.48 (d, J = 15.2 Hz, 1H, CH2), 4.37–4.34 (m, 1H, CH), 4.34–4.31 (m, 2H, CH2), 4.31–4.26 (m, 2H, CH2), 3.71 (d, J = 4.4 Hz, 1H, CH), 3.63 (s, 3H, OCH3), 2.51 (s, 3H, CH3), 1.40–1.37 (m, 3H, CH3), 1.37–1.33 (m, 3H, CH3) ppm; 13C

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

• formula of 1 was assigned to be C15H19NO3S by high-resolution (HR) ESIMS (m/z 294.1180 [M + H]+; calcd. 294.1169 for C15H20NO3S), which indicated the presence of seven double bond equivalents (DBEs). Upon analyzing the 13C NMR spectrum, the DBEs were assigned to two ring structures, two carbon–heteroatom

• structures of compounds 1–6 isolated in this study and of the structurally related siderophores massiliachelin (7) and (S)-dihydroaeruginoic acid (8). 1H,1H-COSY and selected 1H,13C-HMBC correlations in 1. Proposed origin of the isolated compounds 1–6 as well as massiliachelin (7). Domain notation of the

• conversion of a thiazoline into a thiazolidine ring. 1H and 13C NMR spectroscopic data for 1–6 in DMSO-d6. Supporting Information Supporting Information File 90: UV and total ion chromatograms of culture extracts from Massilia sp. NR 4-1. Copies of MS/MS and NMR spectra for new compounds. Acknowledgements

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

• was not given for the different coupling constants between diester 1a and diketone 1b’. In the 13C NMR spectrum of diester 1a, two separate signals of carbonyl groups were observed at 163.2 and 163.3 ppm, indicating that the two ester functionalities were not equivalent. Moreover, the spectrum of

• ) in CDCl3 using TMS as an internal standard. The assignments of the 13C NMR signals were performed by DEPT experiments. IR spectra were recorded on a JASCO FT/IR-4200 spectrometer equipped with an ATR detector. High-resolution mass spectra were obtained on AB SCIEX Triplet TOF 4600 and Bruker Compact

• ), 4.17 (q, J = 1.8, 7.2 Hz, 2H), 4.48–4.37 (m, 1H), 4.81–4.72 (m, 1H), 4.97–4.88 (m, 2H), 7.09 (d, J = 8.0 Hz, 2H), 7.18 (d, J = 8.0 Hz, 2H), 7.48 (dd, J = 7.6, 7.2 Hz, 2H), 7.61 (t, J = 7.6 Hz, 1H), 8.05 (d, J = 7.2 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ 13.6 (CH3), 21.1 (CH3), 42.8 (CH), 57.1 (CH), 61.9

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

• commercially available benzonitriles [39] or by thionation of the corresponding N-substituted amides [40] using pyridine–P4S10 as sulfurization agent. Other chemicals and solvents were purchased from Acros Organics, Sigma-Aldrich, and Fluorochem and were used as received. 1H and 13C (APT) NMR spectra were

• recorded on a Bruker Avance III 400 MHz or on a Bruker Ascend 500 MHz instrument. Chemical shifts (δ) are referenced to TMS (δ = 0) or solvent residual peaks δ(CDCl3) = 7.24 ppm (1H) and 77.0 ppm (13C), δ(DMSO-d6) = 2.50 ppm (1H) and 39.6 ppm (13C). High-resolution mass spectra were recorded on a MALDI LTQ