Using UHPLC–MS profiling for the discovery of new sponge-derived metabolites and anthelmintic screening of the NatureBank bromotyrosine library

• Sasha Hayes,
• Aya C. Taki,
• Kah Yean Lum,
• Joseph J. Byrne,
• Merrick G. Ekins,
• Robin B. Gasser and
• Rohan A. Davis

Beilstein J. Org. Chem. 2022, 18, 1544–1552, doi:10.3762/bjoc.18.164

• profiling reported here will be targeted for follow-up large-scale chemical investigations in the future. Experimental General experimental procedures Specific rotations were recorded using a JASCO P-1020 polarimeter. IR data were acquired on a Universal Attenuated Total Reflectance (UATR) Two attachment on

• film; UV (MeOH) λmax (log ε) 283 (3.02) nm; UV (MeOH + NaOH) λmax (log ε) 236 (3.53), 300 (2.94) nm; IR (UATR) vmax 3357, 1678, 1429, 1204, 1140 cm−1; 1H and 13C NMR data, Table 1; (+)-LRESIMS m/z 382/384 (1:1) [M + H]+; (−)-LRESIMS m/z 380/382 (1:1) [M − H]−; (+)-HRESIMS m/z 382.0507 [M + H]+ (calcd

A facile approach to spiro[dihydrofuran-2,3'-oxindoles] via formal [4 + 1] annulation reaction of fused 1H-pyrrole-2,3-diones with diazooxindoles

• Pavel A. Topanov,
• Anna A. Maslivets,
• Maksim V. Dmitriev,
• Irina V. Mashevskaya,
• Yurii V. Shklyaev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2022, 18, 1532–1538, doi:10.3762/bjoc.18.162

• the solution being turned from purple to red. The starting FPD 1a is bright violet; thus, the disappearance of the violet color was used as an indicator of the reaction’s completion. Product 3aa was isolated as yellow crystals in 73% yield and characterized by NMR, IR, and mass spectra, and single

Cyclometalated iridium complexes-catalyzed acceptorless dehydrogenative coupling reaction: construction of quinoline derivatives and evaluation of their antimicrobial activities

• Hongling Shui,
• Yuhong Zhong,
• Renshi Luo,
• Zhanyi Zhang,
• Jiuzhong Huang,
• Ping Yang and
• Nianhua Luo

Beilstein J. Org. Chem. 2022, 18, 1507–1517, doi:10.3762/bjoc.18.159

• as raw material. In order to solve such problems, chemists have developed ADC reactions catalyzed by metal complexes (such as Ir [18][19], Ru [20][21][22][23][24], Re [25], Mn [26][27], Pd [28], Ni [29], Cu [30], etc.) to synthesize quinolines using o-aminobenzyl alcohol as starting material. ADC

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• . Hydrazinium dihydrochloride was isolated in some cases (confirmed by X-ray, mp, and FT-IR data) demonstrating the degradation of the heteroadamantane cage. Deprotection of Cbz derivatives by hydrogenation over Pd–C was more productive. Thus, hydrogenolysis of product 8b delivered the 1N,2O-TAAD derivative 15

Mechanochemical synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalysts for the synthesis of α-aryloxy alcohols via asymmetric phenolic kinetic resolution of terminal epoxides

• Shengli Zuo,
• Shuxiang Zheng,
• Jianjun Liu and
• Ang Zuo

Beilstein J. Org. Chem. 2022, 18, 1416–1423, doi:10.3762/bjoc.18.147

• peak at around 13 ppm was assigned to the phenolic OH groups. The signal at around 1615 cm−1 in the IR spectrum could also indicate the formation of imine (see Supporting Information File 1). In addition to the use of grinding technology, a self-made ball mill was applied to the synthesis of

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

• yellow amorphous powder. The negative HRESIMS [M − H]− at m/z 371.1133 (calcd for 371.1136) suggested its molecular formula to be C20H20O7, corresponding to 11 degrees of unsaturation. The IR spectrum showed absorption bands characteristic of hydroxy group (3450 cm−1), carbonyl (1765 cm−1), and aromatic

• molecular formula was determined to be C20H24O6 by the HRESIMS peak at m/z 359.1497 [M − H]− (calcd for 359.1500). The IR spectrum of 2 showed the presence of hydroxy (3417 cm−1) and aromatic (1593, 1509 cm−1) groups. The 1H NMR spectrum recorded in MeOH-d4 (Table 1) of compound 2 displayed signals for two

• (Figure 2) from δH 3.76 (4-OCH3, 4′-OCH3) to δC 135.9 (C-4, C-4′). The absorption band near 999 cm−1 in the IR spectrum (Figure S26 in Supporting Information File 1) indicated that the double bond has an E configuration [16][17][18][19]. Therefore, the structure of compound 2 was established as shown in

Synthesis of meso-pyrrole-substituted corroles by condensation of 1,9-diformyldipyrromethanes with pyrrole

• Baris Temelli and
• Pinar Kapci

Beilstein J. Org. Chem. 2022, 18, 1403–1409, doi:10.3762/bjoc.18.145

• hertz (Hz). IR spectra were recorded on FTIR spectrometer (Thermo Scientific, Nicolet IS10). HRMS were measured in ESI mode and the mass analyzer of the HRMS was TOF (Agilent 6224 TOF LC–MS). Flash column chromatography was performed on silica gel (230–400 mesh). 5-Substituted dipyrromethanes [35] and

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

• (chlorophenyl)ethynes 3b,c to form triarylcyclopropenylium salts 5b,c in 22 and 15% yield (Scheme 2). Unfortunately, it was not possible to synthesize tris(2-chlorophenyl)cyclopropenylium bromide 5a using this method. The structures of 3–5 were confirmed by 1H and 13C NMR as well as IR spectroscopic methods and

Enantioselective total synthesis of putative dihydrorosefuran, a monoterpene with an unique 2,5-dihydrofuran structure

• Irene Torres-García,
• Josefa L. López-Martínez,
• Rocío López-Domene,
• Manuel Muñoz-Dorado,
• Ignacio Rodríguez-García and
• Miriam Álvarez-Corral

Beilstein J. Org. Chem. 2022, 18, 1264–1269, doi:10.3762/bjoc.18.132

• -methylhepta-5,6-dienoate (3, 225 mg, 81%) isolated as light yellow oil. IR (ATR) ν (cm−1): 3434, 2972, 2928, 1958, 1723, 1436, 1374, 1172, 1028, 925, 853; 1H NMR (300 MHz, CDCl3) δ 4.77 (dq, J = 2.3, 3.2 Hz, 2H), 4.12 (q, J = 7.1 Hz, 2H), 4.05 (m, 1H), 2.42 (t, J = 7.2 Hz, 2H), 2.18 (s, 1H), 2.04–1.77 (m, 2H

• is formed as side product (0–10%) when the HCl solution used for the workup has a concentration higher than 3%. Compound 5: IR (ATR) ν (cm−1): 2982, 2927, 1960, 1772, 1427, 1331, 1162, 974, 918, 855; 1H NMR (300 MHz, CDCl3) δ 4.89 (m, 1H), 4.86 (m, 2H), 2.55 (m, 2H), 2.30 (m, 2H), 1.79 (t, J = 3.1 Hz

• anhydrous MgSO4, and concentrated under reduced pressure. The residue was purified by silica gel flash column chromatography (n-hexane/EtOAc 9:1) to afford ethyl 3-(3-methyl-2,5-dihydrofuran-2-yl)propanoate (2, 57 mg, 88%) isolated as colorless oil. IR (ATR) ν (cm−1): 2969, 2927, 2849, 1731, 1442, 1376

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor: selectivity and utility

• Koichi Mitsudo,
• Haruka Inoue,
• Yuta Niki,
• Eisuke Sato and
• Seiji Suga

Beilstein J. Org. Chem. 2022, 18, 1055–1061, doi:10.3762/bjoc.18.107

• proton-exchange membrane reactor is described. The reduction of enones proceeded smoothly under mild conditions to afford ketones or alcohols. The reaction occurred chemoselectively with the use of different cathode catalysts (Pd/C or Ir/C). Keywords: enone; hydrogenation; iridium; palladium; PEM

• should be controllable by the cathode catalyst and electrochemical parameters. Fortunately, we found that chemoselective reduction of enones 1 can be carried out using different cathode catalysts (Pd/C or Ir/C). Results and Discussion Electroreduction of enones to ketones First, we chose cyclohex-2-en-1

• with Ru catalyst (Table 3, entry 3). Similarly, both 2a and 3a were obtained with Ir and Pt catalyst (Table 3, entries 4 and 5). In particular, 3a was obtained preferentially with the Ir catalyst. These results revealed that the cathode catalysts strongly affected the selectivity between 2a and 3a. Pd

Synthesis, optical and electrochemical properties of (D–π)₂-type and (D–π)₂Ph-type fluorescent dyes

• Kosuke Takemura,
• Kazuki Ohira,
• Taiki Higashino,
• Keiichi Imato and
• Yousuke Ooyama

Beilstein J. Org. Chem. 2022, 18, 1047–1054, doi:10.3762/bjoc.18.106

• OTT-2 to OTK-2. Experimental General methods Melting points were measured with an AS ONE ATM-02 apparatus. IR spectra were recorded on a SHIMADZU IRTracer-100 spectrometer by ATR method. 1H NMR and 13C NMR spectra were recorded on a Varian-500 FT NMR spectrometer. High-resolution mass spectral data by

Isolation and biosynthesis of daturamycins from Streptomyces sp. KIB-H1544

• Yin Chen,
• Jinqiu Ren,
• Ruimin Yang,
• Jie Li,
• Sheng-Xiong Huang and
• Yijun Yan

Beilstein J. Org. Chem. 2022, 18, 1009–1016, doi:10.3762/bjoc.18.101

• us to explore their biosynthesis, especially the mechanism of cyclopentenone formation in the diarylcyclopentenones. Experimental General experimental procedures IR spectra were measured on a Bruker Tensor 27 FTIR spectrometer using KBr disks. NMR spectra were performed with a Bruker AV600 MHz

• ): pale yellow solid; IR (KBr) νmax: 3468, 3287, 1731, 1702, 1631, 1398 and 1202 cm−1; UV (MeOH) λmax (log ε): 314 (0.48), 217 (0.28), 202 (0.48); 1H and 13C NMR, see Table 1; HRMS–ESI (m/z): [M + Na]+ calcd for C19H16O5Na+, 347.0890; found, 347.0893. Daturamycin B (2): white powder; 1H and 13C NMR, see

Automated grindstone chemistry: a simple and facile way for PEG-assisted stoichiometry-controlled halogenation of phenols and anilines using N-halosuccinimides

• Dharmendra Das,
• Akhil A. Bhosle,
• Amrita Chatterjee and
• Mainak Banerjee

Beilstein J. Org. Chem. 2022, 18, 999–1008, doi:10.3762/bjoc.18.100

• . Moreover, up to 95% of the side product succinimide was also isolated, and considering its possible conversion to NBS [44] it is an attribute to this green protocol by lowering the E-factor. The products were well-characterized by 1H NMR, 13C NMR, IR, and CHN analysis. The NMR spectra of the synthesized

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

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

Beilstein J. Org. Chem. 2022, 18, 991–998, doi:10.3762/bjoc.18.99

• in the reaction. Because there is only one chiral carbon atom in the molecule, there are no diastereoisomers in the obtained products 3a–l. The chemical structures of compounds 3a–l were fully characterized by IR, HRMS, 1H and 13C NMR spectra. As for an example, the 1H NMR spectrum of compound 3i

Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds: density functional theory study on product selectivity

• Naoki Kise and
• Toshihiko Sakurai

Beilstein J. Org. Chem. 2022, 18, 956–962, doi:10.3762/bjoc.18.95

• cyclization step. Experimental General information. The 1H NMR (500 MHz) and 13C NMR (125 MHz) spectra were measured on a JEOL GMX-500 spectrometer with tetramethylsilane (TMS) or the residual signals of protonated solvents as an internal standard: CDCl3 (δ = 77.0 in 13C NMR). IR spectra were recorded on a

Introducing a new 7-ring fused diindenone-dithieno[3,2-b:2',3'-d]thiophene unit as a promising component for organic semiconductor materials

• Valentin H. K. Fell,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Eman J. Hussien and
• Peter J. Skabara

Beilstein J. Org. Chem. 2022, 18, 944–955, doi:10.3762/bjoc.18.94

• V (ΔEp = 0.06 V), respectively. UV–vis absorption spectroelectrochemistry (see Figures S20 and S21 in Supporting Information File 1) shows the evolution of the dication and dianion states with the longest wavelength absorption band extending into the near-IR with broad features, characteristic of

Anti-inflammatory aromadendrane- and cadinane-type sesquiterpenoids from the South China Sea sponge Acanthella cavernosa

• Shou-Mao Shen,
• Qing Yang,
• Yi Zang,
• Jia Li,
• Xueting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 916–925, doi:10.3762/bjoc.18.91

• MeCN at 4 °C in the present study. Compound (+)-1 was obtained as an optically active colorless oil. Its molecular formula was deduced to be C15H22O2 on the basis of HRESIMS [quasi-molecular ion peak at m/z 235.1700 ([M + H]+, calcd for 235.1693)]. The IR spectrum displayed an absorption band of an α,β

• with 4. The IR absorption band at 3386 cm−1 suggested the presence of hydroxy groups. A careful analysis of its 1D and 2D NMR spectra revealed that the NMR spectroscopic features of compound 5 (Table 1 and Figures S24–S31 in Supporting Information File 1) extremely resembled those of 4. The main

• -4 micro-melting point apparatus (Shanghai Precision Scientific Apparatuses Co., Ltd, Shanghai, China). Optical rotations were measured on a Perkin-Elmer 241MC polarimeter (PerkinElmer, Fremont, CA, USA). IR spectra were recorded on a Nicolet 6700 spectrometer (Thermo Scientific, Waltham, MA, USA

Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

• Mengjie Wang,
• Lanping Dang,
• Wan Xu,
• Zhiying Ma,
• Liuliu Shao,
• Guangxia Wang,
• Chunli Li and
• Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

• employed. All starting materials and reagents were commercially available. 1H NMR and 13C{1H} NMR spectra were recorded on 300 or 400 MHz NMR instruments using CDCl3 as solvent. The chemical shift references were as follows: (1H) CDCl3, 7.26 ppm (CHCl3); (13C{1H}) CDCl3, 77.00 ppm (CDCl3). IR spectra were

• (d, J = 16.0 Hz, 2H), 6.93 (d, J = 16.0 Hz, 2H), 0.39 (s, 18H); 13C{1H} NMR (100 MHz, CDCl3) δ (ppm) 145.3, 144.7, 143.7, 140.7, 138.4, 137.8, 137.2, 129.1, 127.8, 125.5, 124.9, 124.4, 122.8, 118.0, −0.1; IR (KBr): 3018, 2958, 2849, 1631, 1408, 1360, 945, 837 cm−1; EIMS (70 eV) m/z: [M]+ 662.18 (40

• MHz, CDCl3) δ (ppm) 7.73 (s, 2H), 7.55 (d, J = 12.9 Hz, 3H), 7.38–7.32 (m, 5 H), 6.79 (d, J = 15.6 Hz, 2H), 0.38 (s, 18H); 13C{1H} NMR (100 MHz, CDCl3) δ (ppm) 151.6, 149.7, 144.5, 142.6, 141.1, 137.01, 136.98, 129.2, 128.6, 127.5, 125.6, 124.9, 124.4, 121.0, 0.2; IR (KBr): 3011, 2949, 2891, 1627

Copper-catalyzed multicomponent reactions for the efficient synthesis of diverse spirotetrahydrocarbazoles

• Shao-Cong Zhan,
• Ren-Jie Fang,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 796–808, doi:10.3762/bjoc.18.80

• , 121.8, 121.5, 120.2, 119.1, 110.7, 110.7, 109.0, 56.1, 50.0, 48.8, 43.6, 25.4; IR(KBr) υ: 3367, 3210, 3155, 3017, 2980, 2831, 2864, 1877, 1623, 1611, 1507, 1456, 1355, 1241, 1178, 1143, 955, 931, 849, 789 cm−1; HRMS–ESI (m/z): [M + Na]+ calcd for C39H30N2O2, 581.2199; found, 581.2191. 2. General

• , 29.1; IR(KBr) υ: 3355, 3207, 3117, 3048, 2963, 2831, 2167, 1871, 1641, 1633, 1554, 1431, 1370, 1240, 1131, 1100, 972, 961, 881, 764 cm−1; HRMS–ESI (m/z): [M + Na]+ calcd for C34H24N4O, 527.1842; found, 527.1849. 3. General procedure for the preparation of the tetrahydrospiro[carbazole-3,5'-pyrimidines

• , 129.1, 128.7, 128.3, 128.0, 126.3, 126.1, 125.5, 124.7, 124.2, 123.1, 120.8, 29.6, 28.8, 21.4, 21.3; IR (KBr) υ: 3219, 3158, 3043, 2966, 2900, 1843, 1755, 1648, 1617, 1537, 1466, 1358, 1318, 1266, 1150, 987, 899, 765 cm−1; HRMS–ESI (m/z): [M + Na]+ calcd for C31H25N3O3, 510.1788; found, 510.1788. 4

Synthesis of bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via cyclopropene cycloadditions to the stable azomethine ylide derived from Ruhemann's purple

• Alexander S. Filatov,
• Olesya V. Khoroshilova,
• Anna G. Larina,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2022, 18, 769–780, doi:10.3762/bjoc.18.77

• asymmetric 1,3-dipolar cycloaddition of azomethine ylides and cyclopropenes catalyzed by a chiral Cu-(CH3CN)4BF4/Ph-Phosferrox complex for the construction of 3-azabicyclo[3.1.0]hexane derivatives [25]. Another concise enantioselective approach towards 3-azabicyclo[3.1.0]hexanes is based on a Cp*Ir-catalyzed

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• temperature control can be ensured, e.g., by IR pyrometers. 2.2 Application of trickle bed reactor systems for isopulegol production Berenguer-Murcia et al. [25] developed a near isothermal micro trickle bed reactor operated by radiofrequency (RF; 300 kHz) heating of nickel ferrite particles (110 µm

• in that the actual temperature of the glass/metal surface could be determined locally using a high-resolution IR camera. It was found to be 950 °C and not 185 °C of the reaction mixture itself. These studies are noteworthy because it can be assumed that the temperatures determined by Organ locally on

Tri(n-butyl)phosphine-promoted domino reaction for the efficient construction of spiro[cyclohexane-1,3'-indolines] and spiro[indoline-3,2'-furan-3',3''-indolines]

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

Beilstein J. Org. Chem. 2022, 18, 669–679, doi:10.3762/bjoc.18.68

• of electron-donating methyl groups in the isatins gave higher yields than electron-withdrawing groups such as chloro and fluoro substituents. The structures of the spiro compounds 8a–m were fully characterized by their IR, HRMS, 1H and 13C NMR spectra. In addition, the single crystal structure of

• , 128.0, 127.1, 127.0, 123.0, 112.3, 110.9, 60.3, 49.0, 44.6, 44.4, 42.6, 21.4, 21.2; IR (KBr) ν: 3727, 3405, 3029, 2921, 2863, 2317, 1911, 1709, 1609, 1501, 1443, 1362, 1295, 1185, 1049, 1022, 959, 920, 820, 732 cm−1; HRMS–ESI (m/z): [M + Na]+ calcd for C38H31NaN3O2, 584.2314; found, 584.2306. 2. General

• ), 2.20 (s, 3H, CH3), 1.30 (t, J = 7.2 Hz, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ 200.0, 175.1, 170.6, 140.6, 139.0, 138.8, 136.8, 135.0, 134.8, 131.6, 131.2, 130.1, 129.8, 129.3, 129.0, 128.6, 128.5, 127.5, 127.4, 127.1, 124.5, 110.2, 61.8, 53.0, 50.7, 43.4, 42.5, 42.0, 21.4, 21.0, 14.1; IR (KBr) ν: 3723

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• of the guest molecule was proven by UV–vis and IR spectroscopy. The multicomponent prism (Figure 3) was finally utilized as a heterogeneous catalyst for Michael and Diels–Alder (DA) reactions in water, representing an uncommon hydrogen-bond donating heterogeneous catalyst [59]. Intrigued by the

Chemistry of polyhalogenated nitrobutadienes, 17: Efficient synthesis of persubstituted chloroquinolinyl-1H-pyrazoles and evaluation of their antimalarial, anti-SARS-CoV-2, antibacterial, and cytotoxic activities

• Viktor A. Zapol’skii,
• Isabell Berneburg,
• Ursula Bilitewski,
• Melissa Dillenberger,
• Katja Becker,
• Stefan Jungwirth,
• Aditya Shekhar,
• Bastian Krueger and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2022, 18, 524–532, doi:10.3762/bjoc.18.54

• (1H, 13C, 14N, 15N NMR, IR, MS and HRMS), copies of spectra, and detailed procedures of biological assays. Acknowledgements We thank Dr. G. Dräger (Leibniz University of Hannover, Germany) for HRMS measurements, Siegrid Franke (Biochemistry and Molecular Biology Interdisciplinary Research Center

Sesquiterpenes from the soil-derived fungus Trichoderma citrinoviride PSU-SPSF346

• Wiriya Yaosanit,
• Vatcharin Rukachaisirikul,
• Souwalak Phongpaichit,
• Sita Preedanon and
• Jariya Sakayaroj

Beilstein J. Org. Chem. 2022, 18, 479–485, doi:10.3762/bjoc.18.50

• ] (Figure 1). Their structures were elucidated on the basis of analysis of their spectroscopic data including IR, UV, NMR, and MS. The relative configuration was assigned based on NOEDIFF data. Furthermore, the absolute configuration of compound 1 was determined by comparison of its specific rotation and

• previously reported. Trichocitrinovirene A (1) was isolated as a colorless gum and had the molecular formula C15H22O5 on the basis of the HRESIMS peak at m/z 305.1359 [M + Na]+. The IR spectrum exhibited absorption bands at 3336, 1684, and 1649 cm−1 for hydroxy, conjugated carboxyl carbonyl, and double bond

• determined on the basis of the HRESIMS peak at m/z 321.1320 [M + Na]+. The IR spectrum was similar to that of compound 1, indicating that they possessed similar functional groups. The 1H NMR spectrum (Table 1) displayed characteristic signals for two geminal olefinic protons (δH 5.93 and 5.52, each s, 1H