Total synthesis of the O-antigen repeating unit of Providencia stuartii O49 serotype through linear and one-pot assemblies

• Tanmoy Halder and
• Somnath Yadav

Beilstein J. Org. Chem. 2021, 17, 2915–2921, doi:10.3762/bjoc.17.199

• , DEPT-135, 13C NMR, COSY, and HSQC as well as mass spectrometry using HRMS. The NMR data were found to correlate well with the data reported for the natural polysaccharide [38]. Conclusion In conclusion, the trisaccharide repeating unit of the O-polysaccharide of Providencia stuartii O49 in its p

Selective sulfonylation and isonitrilation of para-quinone methides employing TosMIC as a source of sulfonyl group or isonitrile group

• Chuanhua Qu,
• Run Huang,
• Yong Li,
• Tong Liu,
• Yuan Chen and
• Guiting Song

Beilstein J. Org. Chem. 2021, 17, 2822–2831, doi:10.3762/bjoc.17.193

• methides with TosMIC.a Supporting Information Supporting Information File 374: General information, characterization data, and copies of 1H and 13C NMR spectra. Acknowledgements We would like to thank Ms H. Z. Liu for obtaining the LC–MS and NMR data. Funding We gratefully acknowledge the National

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• were no significant differences in the chemical shift values between the quinoline precursor and new Schiff bases regarding the aromatic resonances in the 1H NMR and 13C NMR data. Studies in the literature have reported that the imine group may exist as E/Z geometrical isomers in the –CH=N double bond

Highly stereocontrolled total synthesis of racemic codonopsinol B through isoxazolidine-4,5-diol vinylation

• Lukáš Ďurina,
• Anna Ďurinová,
• František Trejtnar,
• Ľuboš Janotka,
• Lucia Messingerová,
• Jana Doháňošová,
• Ján Moncol and
• Róbert Fischer

Beilstein J. Org. Chem. 2021, 17, 2781–2786, doi:10.3762/bjoc.17.188

• -methoxycinnamaldehyde (6). Thus, the reaction of 6 with N-Cbz-protected hydroxylamine 7 catalyzed by ᴅʟ-proline in chloroform gave racemic 5-hydroxyisoxazolidine 8 in 77% yield almost as a sole trans isomer (dr > 9:1). Its structure was confirmed by comparison with already reported NMR data for the known (3S,5S

• -(hydroxyamino)-α,β-diol 4 (dr > 95:5) in 73% yield (Scheme 3). Its relative configuration was determined by comparison with already reported NMR data of related γ-(hydroxyamino)-α,β-diols [17]. More specifically, the value of the vicinal coupling constant J2,3 = 1.8 Hz and the chemical shift of the H-2 proton

Synthesis of new pyrazolo[1,2,3]triazines by cyclative cleavage of pyrazolyltriazenes

• Nicolai Wippert,
• Martin Nieger,
• Claudine Herlan,
• Nicole Jung and
• Stefan Bräse

Beilstein J. Org. Chem. 2021, 17, 2773–2780, doi:10.3762/bjoc.17.187

• -triazine derivatives. Molecular structures of compounds 12h (A) and 13c (B) representing both possible regioisomers of the alkylation reaction (displacement parameters are drawn at the 50% probability level). The X-ray data corroborate the obtained NMR data. Graphical overview about selected pyrazolo[1,2,3

Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 2450–2461, doi:10.3762/bjoc.17.162

• -layer chromatography (TLC). Organic compounds were purified using commercial Merck silica gel (0.043–0.06 mm) with a fluorescence indicator (the visualization was performed under UV light at 254 nm). All solvents for work-up and column chromatography were distilled before use. NMR data were recorded in

Synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

• Andrey I. Puzanov,
• Dmitry S. Ryabukhin,
• Anna S. Zalivatskaya,
• Dmitriy N. Zakusilo,
• Darya S. Mikson,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2417–2424, doi:10.3762/bjoc.17.158

• ), oxadiazole 3a gave the product of hydration of the acetylene bond (4d, yield of 65%) existing in solution as equilibrium between ketone and enol forms in a ratio of 1.2:1 according to NMR data (see Supporting Information File 1). Then, reactions of 5-acetylenyl-1,2,4-oxadiazole 3a–d with arenes (benzene and

Isolation and characterization of new phenolic siderophores with antimicrobial properties from Pseudomonas sp. UIAU-6B

• Emmanuel T. Oluwabusola,
• Olusoji O. Adebisi,
• Fernando Reyes,
• Kojo S. Acquah,
• Mercedes De La Cruz,
• Larry L. Mweetwa,
• Joy E. Rajakulendran,
• Digby F. Warner,
• Deng Hai,
• Rainer Ebel and
• Marcel Jaspars

Beilstein J. Org. Chem. 2021, 17, 2390–2398, doi:10.3762/bjoc.17.156

• secondary metabolites 1–5 including pseudomonin A–C (1–3) and pseudomobactins A and B (4 and 5). The two known compounds, pseudomonine (6) and salicylic acid (7) were also isolated as the major constituents of the extracts and their structures were determined by analysis of HRESIMS, 1D and 2D NMR data (see

• that revealed a molecular ion at m/z 237.0874 (calcd for C11H13N2O4−, 237.0880). A thorough analysis of 1H and 2D NMR data (see Table 1 and Supporting Information File 1) showed four aromatic methines, two aliphatic methines, one methyl, and four quaternary carbons signals at δC 162.9 (C-1), 113.2 (C-6

• −9.5 (c 0.02, MeOH); UV (MeOH) λmax, nm (log ε): 276 (3.23); IR (cm−1) νmax: 3333, 1677 1660, 1538, 1493, 1203, 1138; NMR data, see Table 1; HRESIMS (m/z): [M − 1]− calcd for C11H13N2O4, 237.0880; found, 237.0874, Δ = −2.53 ppm. Pseudomonin B (2): yellowish oil; [α]D25 −13.3 (c 0.05, MeOH); UV (MeOH

Phenolic constituents from twigs of Aleurites fordii and their biological activities

• Kyoung Jin Park,
• Won Se Suh,
• Da Hye Yoon,
• Chung Sub Kim,
• Sun Yeou Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2021, 17, 2329–2339, doi:10.3762/bjoc.17.151

• (1–3), a new phenolic glycoside (15), a new cyanoglucoside (16), and 14 known compounds (4–14 and 17–19) (Figure 1). Compound 1 was obtained as a colorless gum. The molecular formula was determined to be C25H32O11 from the [M + Na]+ molecular ion peak in the positive mode HRFABMS. The 1H NMR data

• 5.51 (d, J = 6.1 Hz, H-7)], an anomeric proton of a sugar [δH 4.27 (d, J = 7.8 Hz, H-1′′)], and a methoxy group [δH 3.84 (s, 3-OCH3)]. The 13C NMR data (Table 1) showed 25 peaks including 12 aromatic carbons [δC 147.6 (C-3), 145.9 (C-4), 145.1 (C-4′), 140.4 (C-3′), 135.2 (C-1′), 133.7 (C-1), 128.3 (C-5

• -rhamnopyranoside and was named as aleuritiside B. Compound 3 was obtained as a colorless gum after purification with a molecular formula of C26H36O11 as deduced from the positive molecular ion peak [M + Na]+ at m/z 547.2155 (calcd for C26H36O11Na, 547.2155) in the HRESIMS. Analysis of the 1H and 13C NMR data

Nomimicins B–D, new tetronate-class polyketides from a marine-derived actinomycete of the genus Actinomadura

• Zhiwei Zhang,
• Tao Zhou,
• Taehui Yang,
• Keisuke Fukaya,
• Enjuro Harunari,
• Shun Saito,
• Katsuhisa Yamada,
• Chiaki Imada,
• Daisuke Urabe and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2194–2202, doi:10.3762/bjoc.17.141

• ). Nomimicin B (1) Colorless amorphous solid; [α]D23 −29 (c 0.10, MeOH); UV (MeOH) λmax (log ε) 246 (3.83), 293 nm (3.71); ECD (c 9.5 × 10−5, MeOH) λext (Δε) 208 (−5.27), 247 (+3.72), 294 nm (−1.24); IR νmax: 3360, 2965, 1755, 1619, 1408, 1088, 998 cm−1; see Table 1 for 1H and 13C NMR data; HRESITOFMS (m/z

• , 1007 cm−1; see Table 1 for 1H and 13C NMR data; HRESITOFMS (m/z): [M + Na]+ calcd for C30H40O7Na, 535.2666; found, 535.2665. Nomimicin D (3) Colorless amorphous solid; [α]D23 −70 (c 0.10. MeOH); UV (MeOH) λmax (log ε) 243 (3.99), 302 nm (3.54); IR νmax: 3380, 2963, 1723, 1619, 1413, 1258, 1010 cm−1

• ; see Table 2 for 1H and 13C NMR data; HRESITOFMS (m/z): [M + Na]+ calcd for C30H40O6Na, 519.2717; found, 519.2717. Nomimicin A (4) Colorless amorphous solid; [α]D23 −87 (c 0.10. CHCl3, lit. [α]D23 −94 (c 0.10. CHCl3) [15]); UV (MeOH) λmax (log ε) 242 (3.73), 298 nm (3.59); ECD (c 1.0 × 10−4, MeOH) λext

2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli,
• Noureddine Chaaben,
• Kamel Alimi,
• Stefan Jopp and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 1629–1640, doi:10.3762/bjoc.17.115

• before use. NMR data were recorded on Bruker ARX 300 instruments in CDCl3 with tetramethylsilane as the internal standard (signals due to the solvent; CHCl3: δ 7.26 for 1H and δ 77.16 for 13C). The 1H NMR chemical shifts and coupling constants were determined assuming first-order behavior. Peak

Chemical synthesis of C6-tetrazole ᴅ-mannose building blocks and access to a bioisostere of mannuronic acid 1-phosphate

• Eleni Dimitriou and
• Gavin J. Miller

Beilstein J. Org. Chem. 2021, 17, 1527–1532, doi:10.3762/bjoc.17.110

• % NaHCO3, EtOH, THF, rt, 24 h, 72%. Supporting Information Supporting Information File 218: Detailed experimental protocols and characterisation data; spectral NMR data (1H, 13C, 31P and HSQC NMR for compounds 2–5, 7–14, 16–18, 20 and 21). Acknowledgements We thank the EPSRC UK National Mass Spectrometry

Total synthesis of ent-pavettamine

• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2021, 17, 1440–1446, doi:10.3762/bjoc.17.99

• : NMR data of all compounds. Supporting Information File 179: Crystal structure data for compound 4. Supporting Information File 180: Crystal structure data for compound 9. Funding The authors would like to thank the National Research Foundation (NRF) and the University of the Witwatersrand for

Analogs of the carotane antibiotic fulvoferruginin from submerged cultures of a Thai Marasmius sp.

• Birthe Sandargo,
• Leon Kaysan,
• Rémy B. Teponno,
• Christian Richter,
• Benjarong Thongbai,
• Frank Surup and
• Marc Stadler

Beilstein J. Org. Chem. 2021, 17, 1385–1391, doi:10.3762/bjoc.17.97

• like hercynolactone. However, NMR data analysis disclosed that the position C-9 (δC 70.8) is hydroxylated. The ROESY spectrum indicates H-9 (δH 4.88) to be cofacial with H-5 and H-13. Thus, fulvoferruginin F could also be named 9-hydroxyhercynolactone [9]. Assessing the bioactivity of the

• are provided in Supporting Information File 1. Fulvoferruginin B (2): faint yellow solid; [α]D20 +14 (c 1, MeOH); UV (MeOH) λmax (log ε) 200 (3.7), 249 (3.5) nm; 1H NMR and 13C NMR data (1H 700 MHz, 13C 175 MHz) in CD3OD: see Table 1; HRMS–ESI (m/z): [M + H]+ calcd for C15H21O3+, 249.1477; found

Nitroalkene reduction in deep eutectic solvents promoted by BH₃NH₃

• Chiara Faverio,
• Monica Fiorenza Boselli,
• Patricia Camarero Gonzalez,
• Alessandra Puglisi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2021, 17, 1041–1047, doi:10.3762/bjoc.17.83

• characterization and NMR data. Funding M. B. thanks MUR for the project PRIN 2017 “NATURECHEM. M. B. thanks Università degli Studi di Milano for the PSR 2019-financed project “Catalytic strategies for the synthesis of high added-value molecules from bio-based starting material”. M. B. and P. C. G. thank the ITN

Application of the Meerwein reaction of 1,4-benzoquinone to a metal-free synthesis of benzofuropyridine analogues

• Rashmi Singh,
• Tomas Horsten,
• Rashmi Prakash,
• Swapan Dey and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 977–982, doi:10.3762/bjoc.17.79

• . Electrophilic aromatic substitution of 6-hydroxybenzofuro[2,3-b]pyridine (13). Synthesis of isomeric oxazole-fused derivatives. Fused derivatives from 16. Supporting Information Supporting Information File 164: Experimental part as well as 1H and 13C NMR data. Funding We thank the KU Leuven for financial

A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson’s reagent

• Ke Wu,
• Yichen Ling,
• An Ding,
• Liqun Jin,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2021, 17, 805–812, doi:10.3762/bjoc.17.69

• phase separation. Modified process for the synthesis of pincer ligand 4. Modified process for the synthesis of pincer-type ligand 6. Synthesis of thioamides a. Supporting Information Supporting Information File 72: NMR data for compounds 2–6 and thiophosphonic acid. Funding This work was supported by

Effective microwave-assisted approach to 1,2,3-triazolobenzodiazepinones via tandem Ugi reaction/catalyst-free intramolecular azide–alkyne cycloaddition

• Maryna O. Mazur,
• Oleksii S. Zhelavskyi,
• Eugene M. Zviagin,
• Svitlana V. Shishkina,
• Vladimir I. Musatov,
• Maksim A. Kolosov,
• Elena H. Shvets,
• Anna Yu. Andryushchenko and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2021, 17, 678–687, doi:10.3762/bjoc.17.57

• ). Ugi product 6aaa (first letter – isocyanide code, second letter – amine code, third – carboxylic acid code) was the first to isolate in our trials and its structure was confirmed by X-ray analysis (Figure 3) in addition to mass spectrometry, elemental analysis, 1H and 13C NMR data. Compound 6

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• methanofullerene in the reaction mixture after the loss of H2 depends on the diazo compound used for the cycloaddition. According to 13C NMR data, the [6,5]-bridged compound 5 has an open transannular bond, while the [6,6]-bridged compound 6 has a closed trans-ring bond. A synthetically interesting building block

Menthyl esterification allows chiral resolution for the synthesis of artificial glutamate analogs

• Kenji Morokuma,
• Shuntaro Tsukamoto,
• Kyosuke Mori,
• Kei Miyako,
• Ryuichi Sakai,
• Raku Irie and
• Masato Oikawa

Beilstein J. Org. Chem. 2021, 17, 540–550, doi:10.3762/bjoc.17.48

• ) [10][11][12]. Since 10 was obtained as crystals, the configurational analysis was thereafter confirmed by single-crystal X-ray analysis, as shown in Figure 4. The conformational differences for 10 between the results of the calculations and the analysis of the NMR data compared to the situation in the

Synthesis of legonmycins A and B, C(7a)-hydroxylated bacterial pyrrolizidines

• Wilfred J. M. Lewis,
• David M. Shaw and
• Jeremy Robertson

Beilstein J. Org. Chem. 2021, 17, 334–342, doi:10.3762/bjoc.17.31

• a chemical and biosynthetic perspective. Their emergence dates back to 1977 with a patent filing from The Upjohn Company describing an unidentified ‘antibiotic 354’ isolated as a fermentation product of Streptomyces puniceus subsp. doliceus; spectroscopic characterization, including 1H NMR data, was

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• ether from 0 to 50%) afforded the pure ferulates 1a, 1b, 3–9, and 12. 5-Bromo-4-chloro-3-indolyl 5-O-trans-feruloyl-α-ʟ-arabinofuranoside (1a, 107 mg, 0.19 mmol, 73%). Green-yellow foam. The NMR data (CD3OD) were consistent with those previously reported [15]. 4-Nitrophenyl 5-O-trans-feruloyl-α-ʟ

• -arabinofuranoside (1b). The application of the general procedure for enzymatic transesterifications was used with commercial 4-nitrophenyl α-ʟ-arabinofuranoside (50 mg, 0.18, mmol, 1 equiv) and the vinyl ferulate 2 (61 mg, 0.28 mmol, 1.5 equiv) to give 1b (71 mg, 0.16 mmol, 86%) as a yellowish powder. The NMR data

• solid. [α]D20 0 (c 2.0, CH3OH). The NMR data (CD3OD) of the racemate 11 were consistent with those previously reported for the pure (S)-enantiomer [37] ([α]D20 −52 (c 2.0, CH3OH)). (±)-4-O-(2-Hydroxy-4-nitrophenyl)-1-O-trans-feruloyl-1,2,4-butanetriol (12). The application of the general procedure for

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

• all 3F-Phe labelled sites regardless of the temperature employed, signifying either a single state at low temperatures or fast exchange between the native and near-native states at higher temperatures (40–70 °C). The NMR data obtained also provided evidence of the rapid ring flipping of the 3-FPhe

• ). Each independent intermediate was characterized on the basis of its 19F NMR chemical shift and the kinetics by which each species formed or decayed were evaluated in real-time. By combining the 19F NMR data with that provided by complementary analytical techniques, mass spectrometry (electrospray

Total synthesis of decarboxyaltenusin

• Lucas Warmuth,
• Aaron Weiß,
• Marco Reinhardt,
• Anna Meschkov,
• Ute Schepers and
• Joachim Podlech

Beilstein J. Org. Chem. 2021, 17, 224–228, doi:10.3762/bjoc.17.22

• pressure (Scheme 4). The product 1 could now be purified by a simple chromatography on silica gel and was obtained in 88% yield. NMR spectroscopic data of the natural product had been published by Wang et al. [2] and by Xiao et al. [7] (Table 1). A comparison of the 13C NMR data of the now synthesized

• agreement with the NMR data measured by us, what leaves no reasonable doubt that the synthesized structure 1 is identical with the natural product. Decarboxyaltenusin (1) was screened for toxicity towards human HeLa cells but proved nontoxic at biologically relevant concentrations and showed an LD50 value

• , K2CO3, DMF/acetone 1:2, 80 °C, 43 h (98%). Final steps in the synthesis of biaryl 1. Conditions: h) Pd(OAc)2, SPhos, Cs2CO3, dioxane/H2O 7:1, 70 °C, 18 h, (R = TBS: 98%, containing non-separable impurities; R = Bn: 89%) ; i) R = Bn: Pd/C (10%), H2, THF, 8 bar, 24 h, 40 °C (88%). NMR data of natural and

Multiswitchable photoacid–hydroxyflavylium–polyelectrolyte nano-assemblies

• Alexander Zika and
• Franziska Gröhn

Beilstein J. Org. Chem. 2021, 17, 166–185, doi:10.3762/bjoc.17.17

• spectrum shows a small transformation to form B. The relatively weak intensity suggests that this was not due to the irradiation but the well-known hydrolysis. In case of form B, the 13C NMR data show that the irradiation leads to form Cc, which can be seen from the new peaks at 127 ppm, 134 ppm, and 175