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

• with CH2Cl2/MeOH 97.5:2.5 (v/v) was subjected to a flash chromatography system (PLC 2020, Gilson) equipped with a VP Nucleodur C18 HTec column (10 µm, 250 × 40 mm). The chromatographic separation was performed by using a constant flow rate of 10 mL/min with the mobile phases made with solvent A

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• scent gland macrolides can be biosynthesized by the frogs [7], although the macrolides are produced from the fatty acid biosynthetic pathway. The gas chromatographic separation obtained with the chiral phase also allowed the determination of the identity of the minor diastereomers formed during the

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

• Bilge Banu Yagci,
• Selin Ezgi Donmez,
• Onur Şahin and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

• suitable mobile phase for the column chromatographic separation of the diastereomeric esters 16a and 16b. With the successful isolation of these esters in pure form, both were converted to the corresponding acyl chlorides 6ba and 6bb via an initial basic hydrolysis followed by treatment with oxalyl

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• containing a fused polyhistidine tag. The preceding examples clearly showcase the diversity of applications that have been developed by academic laboratories to enable a particular chromatographic separation. While early versions may still be complex and not trialed by many users outside these groups, it is

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

• step synthesis, though the former involved two extra steps for the synthesis of the first glycosidic donor and one chromatographic separation. The synthesis of the desired product was achieved through manipulations of the appropriate protecting group on the monosaccharides and subsequent realization of

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• oxathiolane derivative 4 with silylated cytosine, which afforded 79 as a mixture of the cis- and trans-nucleosides. The process used N-protected cytosine and further chromatographic separation. The deprotection with a methanolic ammonia solution provided racemic (±)-BCH-189 (1c). In vitro studies of (±)-BCH

• purine nucleobases via N-glycosylation. The anti-HIV activity of the nucleosides 83 was quantified by EC50 values of 94.7 µM and 11.6 µM when X = H or CH3 and Y = OH, respectively [33]. The α-anomers were also isolated by chromatographic separation methods. To study the structure–activity relationships

N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts

• Viera Poláčková,
• Dominika Krištofíková,
• Boglárka Némethová,
• Renata Górová,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176

• which the key intermediate, pyrrolidine derivative 2, can be obtained in three steps according to the literature procedure [32]. Using this method, we obtained the product 2 in a yield comparable (56% overall yield) to that described in the literature. However, the difficult chromatographic separation

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

• Information File 1). It should be noted that attempts of chromatographic separation of triflates 4a–c into individual E- and Z-isomers on silica gel led to a decrease of their yields and a change in E/Z-ratio. That reveals instability of these compounds on silica gel. In the same reaction in H2SO4 (Scheme 4

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• (7g, Scheme 11). However, dimetathesized product (±)-18c was not formed, and isolation of monometathesized products (±)-18a and (±)-18b (or a mixture thereof) in pure form failed despite repeated attempts of chromatographic separation. Finally, isoxazoline (±)-5 was subjected to CM with 4

• attempts of chromatographic separation. Finally, CM reactions between isoxazoline (±)-6 and 4-fluorostyrene (7h) were studied (Scheme 18 and Table 16). HG-2 catalyst provided monocoupled (±)-25a and dicoupled (±)-25c in a comparable amount. With G-2 catalyst, both products were formed in higher yield. G-3

Volatile emission and biosynthesis in endophytic fungi colonizing black poplar leaves

• Christin Walther,
• Pamela Baumann,
• Katrin Luck,
• Beate Rothe,
• Peter H. W. Biedermann,
• Jonathan Gershenzon,
• Tobias G. Köllner and
• Sybille B. Unsicker

Beilstein J. Org. Chem. 2021, 17, 1698–1711, doi:10.3762/bjoc.17.118

• detector (interface temp, 270 °C; quadrupole temp, 150 °C; source temp, 230 °C; electron energy, 70 eV). Chromatographic separation was achieved with an initial oven temperature of 45 °C held for 2 min, which was then increased to 180 °C with a gradient of 6 °C min−1, and then further increased to 300 °C

Copper-mediated oxidative C−H/N−H activations with alkynes by removable hydrazides

• Feng Xiong,
• Bo Li,
• Chenrui Yang,
• Liang Zou,
• Wenbo Ma,
• Linghui Gu,
• Ruhuai Mei and
• Lutz Ackermann

Beilstein J. Org. Chem. 2021, 17, 1591–1599, doi:10.3762/bjoc.17.113

• determined by 1H NMR spectroscopy. Chromatographic separation was carried out on silica gel 60H (200–300 mesh) manufactured by Qingdao Haiyang Chemical Group Co. (China). High-resolution mass spectrometry (HRMS) was measured on a Thermo-DFS mass spectrometer. NMR spectra were recorded on a JEOL 600 NMR

Synthesis of bis(aryloxy)fluoromethanes using a heterodihalocarbene strategy

• Carl Recsei and
• Yaniv Barda

Beilstein J. Org. Chem. 2021, 17, 813–818, doi:10.3762/bjoc.17.70

• undesired isomer were produced, recovery of unreacted 6 was simple and the quantity of 8 (<5%) was reduced compared to all previous attempts. Chromatographic separation permitted the removal of 8 and the isolation of a pure sample of compound 4. Synthesis of compound 1 Having produced the key intermediate 4

β-Lactamase inhibition profile of new amidine-substituted diazabicyclooctanes

• Zafar Iqbal,
• Lijuan Zhai,
• Yuanyu Gao,
• Dong Tang,
• Xueqin Ma,
• Jinbo Ji,
• Jian Sun,
• Jingwen Ji,
• Yuanbai Liu,
• Rui Jiang,
• Yangxiu Mu,
• Lili He,
• Haikang Yang and
• Zhixiang Yang

Beilstein J. Org. Chem. 2021, 17, 711–718, doi:10.3762/bjoc.17.60

• CH2Cl2. The low yield of this reaction was due to the formation of two isomeric products as revealed by TLC and subsequent analysis by analytical LC–MS. The NMR spectra of both isomers, after chromatographic separation, showed different chemical shifts for the protons at C2 position of the DBO ring

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

• be effective here (Scheme 2). Thus, the esterification mediated by 2-methyl-6-nitrobenzoic anhydride (MNBA, Shiina esterification) [9], followed by chromatographic separation of the diastereomers, successfully generated the (2S)-isomer 9* (tR 7.0 min) and the (2R)-isomer 9 (tR 11.5 min) in 45.3% and

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

• Dimas J. P. Lima,
• Antonio E. G. Santana,
• Michael A. Birkett and
• Ricardo S. Porto

Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4

• providing a mixture of monoprotected diols (−)-53 and 54 in a 10:1 ratio for the least sterically hindered alcohol in 98% yield. After chromatographic separation, (−)-53 underwent radical-induced Barton–McCombie deoxygenation (AIBN, Bu3SnH) to form (−)-55 in 82% yield. The double deprotection of (−)-55

• in a 9:1 ratio. After chromatographic separation, alcohol (−)-77a, isolated in 67% yield and >99% de was subjected to a Claisen rearrangement, leading to aldehyde (−)-78 in 79% yield (96% de determined by 1H NMR). (−)-78 was treated with vinylmagnesium bromide to give a mixture of allyl alcohols

• from the carbocupration of 85, a Grignard derivative of 1-heptyne [56]. After a lithium–halogen exchange, the corresponding vinyllithium was treated with p-menthane-3-carboxaldehyde to give the isomeric allylalcohols (−)-87a and (−)-87b in a 5:1 ratio. After chromatographic separation, (−)-adaline (1

Synthesis of tetrafluorinated piperidines from nitrones via a visible-light-promoted annelation reaction

• Vyacheslav I. Supranovich,
• Igor A. Dmitriev and
• Alexander D. Dilman

Beilstein J. Org. Chem. 2020, 16, 3104–3108, doi:10.3762/bjoc.16.260

• also evaluated the construction of fluorinated tetrahydroisoquinoline structures starting from nitrones, but this required four consecutive reactions with different conditions and chromatographic separation at each step [25] (Scheme 1). Herein we report a single-step protocol for the construction of

On the mass spectrometric fragmentations of the bacterial sesterterpenes sestermobaraenes A–C

• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2020, 16, 2807–2819, doi:10.3762/bjoc.16.231

• , Wilmington, USA). The gas chromatographic separation was done using a HP5-MS fused silica capillary column (30 m, 0.25 mm i.d., 0.25 μm film, Agilent). The GC settings were 1) inlet pressure: 77.1 kPa, He 23.3 mL min−1; 2) injector temperature: 250 °C; 3) injection volume: 2 μL; 4) injector operation mode

Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation

• Kumar Godugu,
• Venkata Divya Sri Yadala,
• Mohammad Khaja Mohinuddin Pinjari,
• Trivikram Reddy Gundala,
• Lakshmi Reddy Sanapareddy and
• Chinna Gangi Reddy Nallagondu

Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156

• in an adequate purity without the need for chromatographic separation, and the catalyst was reused 7 times without a significant loss of the catalytic activity. Hence, the catalyst is a greener alternative for the synthesis of 1,2-disubstituted benzimidazoles, dihydropyrimidinones/-thiones, and

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• DMF as the solvent was found to be an excellent sulfur activator, leading to the formation of the desired product 2bA in 50% yield after a short silica gel column chromatographic separation (Table 1, entry 1). The structure of 2bA was confirmed on the basis of spectroscopic data. The 1H NMR spectrum

Ferrocenyl-substituted tetrahydrothiophenes via formal [3 + 2]-cycloaddition reactions of ferrocenyl thioketones with donor–acceptor cyclopropanes

• Grzegorz Mlostoń,
• Mateusz Kowalczyk,
• André U. Augustin,
• Peter G. Jones and
• Daniel B. Werz

Beilstein J. Org. Chem. 2020, 16, 1288–1295, doi:10.3762/bjoc.16.109

• characteristic signals of both CO2Me groups located at 3.38 and 3.81 ppm. After chromatographic separation the expected tetrahydrothiophene 9a was isolated in only 23% yield. As the next model substrate, the sterically crowded diferrocenyl thioketone (8b) was tested as a structural analog of thiobenzophenone

Preparation of 2-phospholene oxides by the isomerization of 3-phospholene oxides

• Péter Bagi,
• Réka Herbay,
• Nikolett Péczka,
• Zoltán Mucsi,
• István Timári and
• György Keglevich

Beilstein J. Org. Chem. 2020, 16, 818–832, doi:10.3762/bjoc.16.75

• hydrolyzed to give the corresponding 3-methyl-2-phospholene oxides 4 in an isomeric ratio above 97:3 and in yields of 71–96% (Table 1). If necessary, the traces of starting material 1 could be removed by simple column chromatography. Efficient chromatographic separation of 2- and 3-phospholene oxide isomers

Isolation of fungi using the diffusion chamber device FIND technology

• Benjamin Libor,
• Henrik Harms,
• Stefan Kehraus,
• Ekaterina Egereva,
• Max Crüsemann and
• Gabriele M. König

Beilstein J. Org. Chem. 2019, 15, 2191–2203, doi:10.3762/bjoc.15.216

• chromatographic separation. RP-HPLC separation of VLC fraction 3.2 (MeOH/H2O 55:45 Phenomenex Luna column (250 × 10 mm, 5 µm, 2 mL/min) obtained 10 fractions (3.2H1–3.2H9). Further HPLC of 3.2H7 and 3.2H9 resulted in the isolation of 1 (3 mg) and 2 (4 mg). Heydenoic acid A (1): yellow oil; [α]D25 −50.0 (c 0.24

Analysis of sesquiterpene hydrocarbons in grape berry exocarp (Vitis vinifera L.) using in vivo-labeling and comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC–MS)

• Philipp P. Könen and
• Matthias Wüst

Beilstein J. Org. Chem. 2019, 15, 1945–1961, doi:10.3762/bjoc.15.190

• effect described by Matucha et al. which results in the gas chromatographic separation of isotopologic substances [28]. In the following, the fully deuterium-labeled compounds are examined and their possible biosynthesis pathways described. However, it was also possible to detect the peaks of the

Design, synthesis and biological evaluation of immunostimulating mannosylated desmuramyl peptides

• Rosana Ribić,
• Ranko Stojković,
• Lidija Milković,
• Mariastefania Antica,
• Marko Cigler and
• Srđanka Tomić

Beilstein J. Org. Chem. 2019, 15, 1805–1814, doi:10.3762/bjoc.15.174

• comparison to the control group. Synthesis of desmuramyl peptides modified at N-terminus. Reagents and conditions: a) TFA/DCM 1:2, rt, 1 h, quantitative; b) EDC·HCl, HOBt·H2O, Et3N, DCM/dioxane 1:1, 0 °C → rt, 48 h, 82%; c) TFA/DCM 1:2, rt, 1 h followed by chromatographic separation of isomers, 43

Synthesis of (macro)heterocycles by consecutive/repetitive isocyanide-based multicomponent reactions

• Angélica de Fátima S. Barreto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2019, 15, 906–930, doi:10.3762/bjoc.15.88

• obtained as a diastereomeric mixture via an Ugi–Nenajdenko reaction using the 4-methyl-2,6,7-trioxabicyclo[2,2,2]octyl (OBO) ester 46 to avoid epimerization of the isocyanide, followed by a reductive amination and chromatographic separation of the isomers; a Passerini–Dömling IMCR led to the heterocyclic