Competing electrophilic substitution and oxidative polymerization of arylamines with selenium dioxide

• Vishnu Selladurai and
• Selvakumar Karuthapandi

Beilstein J. Org. Chem. 2024, 20, 1221–1235, doi:10.3762/bjoc.20.105

• environment. Acetonitrile (99.9%) was bought from Avra Chemicals Private Ltd. and used without any further purification. Selenium dioxide and a range of reactants were purchased from Sigma-Aldrich. TLC was performed using silica-gel-coated aluminum sheets (TLC silica gel 60 F254). 1H, 13C, and 77Se NMR (500

• in a different round-bottom flask, and the solvent was evaporated in a rotary evaporator. The resulting solid was dissolved in DCM, and silica gel was added to the DCM layer. This slurry was subjected to column chromatography on silica gel (100–200 mesh) using petroleum ether and ethyl acetate as

• solid. The filtrate was evaporated and column-chromatographed on silica gel (100–200 mesh) using petroleum ether and ethyl acetate as an eluent. The initial yellowish orange fraction containing N1,N2-bis(2-methoxyphenyl)oxalamide, collected with 22% ethyl acetate, was recrystallized from a chloroform

Introduction of peripheral nitrogen atoms to cyclo-meta-phenylenes

• Koki Ikemoto and
• Hiroyuki Isobe

Beilstein J. Org. Chem. 2024, 20, 1207–1212, doi:10.3762/bjoc.20.103

• overnight to give 3a in 6% yield (272 mg, 0.592 mmol) after the extraction. The latter was purified by silica gel short path and GPC (column: YMC-GPC T30000-40 + T4000-40 + T2000-40, eluent: CHCl3, flow rate: 30 mL/min) to give 3a in 1% yield (52.8 mg, 0.115 mmol) and 3b in 3% yield (118 mg, 0.193 mmol). In

Two-fold addition reaction of silylene to C₆₀: structural and electronic properties of a bis-adduct

• Masahiro Kako,
• Masato Kai,
• Masanori Yasui,
• Michio Yamada,
• Yutaka Maeda and
• Takeshi Akasaka

Beilstein J. Org. Chem. 2024, 20, 1179–1188, doi:10.3762/bjoc.20.100

• accompanied by mono-adduct 2 (22% yield) by silica gel flash column chromatography using mixed solvents of hexane/CH2Cl2 by changing the ratios of volumes from 10:1 to 3:1. In thin-layer chromatography (TLC) analysis using silica gel, the Rf values are 0.55 for 2 and 0.33 for 3, respectively, with hexane

Bismuth(III) triflate: an economical and environmentally friendly catalyst for the Nazarov reaction

• Manoel T. Rodrigues Jr.,
• Aline S. B. de Oliveira,
• Ralph C. Gomes,
• Amanda Soares Hirata,
• Lucas A. Zeoly,
• Hugo Santos,
• João Arantes,
• Catarina Sofia Mateus Reis-Silva,
• João Agostinho Machado-Neto,
• Leticia Veras Costa-Lotufo and
• Fernando Coelho

Beilstein J. Org. Chem. 2024, 20, 1167–1178, doi:10.3762/bjoc.20.99

• different compounds containing the indanone moiety. Synthesis of unsaturated β-ketoesters (Knoevenagel derivatives). aIsolated yield after purification using silica gel column chromatography. Synthesis of 3-aryl-2-ethoxycarbonyl-1-indanones mediated by bismuth triflate. aIsolated yield after purification

• using silica gel column chromatography. bExtensive degradation. cRecovery of starting material. Basic protocol: The Knoevenagel product 9 (0.5 mmol), dry acetonitrile (2 mL), and Bi(OTf)3 (0.05 mmol) were added to a sealed tube. The reaction mixture was stirred at 60 °C and monitored by TLC. Controlled

• decarboxylation directed by bismuth triflate at 100 °C. Synthesis of 3-aryl-1-indanones. aIsolated yield after purification using silica gel column chromatography. bReaction performed at 60 °C. cFrom tert-butyl Knoevenagel derivative. Basic protocol: The Knoevenagel product 9 (0.5 mmol), dry acetonitrile (2 mL

Kinetically stabilized 1,3-diarylisobenzofurans and the possibility of preparing large, persistent isoacenofurans with unusually small HOMO–LUMO gaps

• Qian Liu and
• Glen P. Miller

Beilstein J. Org. Chem. 2024, 20, 1099–1110, doi:10.3762/bjoc.20.97

• obtained using a solvent purification system (Innovative Technologies, Inc.) and handled under a nitrogen atmosphere, unless otherwise noted. Flash chromatography was performed using SiliaFlash® F60 40–63 µm (230–400 mesh) 60 Å silica from Silicycle Inc. and RediSep® Rf Silica Flash Columns (12 g, 24 g or

• 40 g) on a CombiFlash® Rf 200 instrument (Teledyne Isco, Inc.). Evaporation of solvents was accomplished using an IKA® RV 10 digital rotary evaporator. Baker-flex® silica gel IB2-F thin-layer chromatography (TLC) plates were purchased from J.T. Baker. A 4 watt 254 nm lamp (Analtytik Jena Co.) and a

• . The contents of the flask were transferred to a 125 mL separatory funnel and extracted twice with 20 mL of CH2Cl2. The organic extracts were combined, dried over anhydrous Na2SO4 and gravity filtered. The solvent was evaporated at reduced pressure leaving a yellow oil. The oil was purified by silica

Synthesis of 1,4-azaphosphinine nucleosides and evaluation as inhibitors of human cytidine deaminase and APOBEC3A

• Maksim V. Kvach,
• Stefan Harjes,
• Harikrishnan M. Kurup,
• Geoffrey B. Jameson,
• Elena Harjes and
• Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2024, 20, 1088–1098, doi:10.3762/bjoc.20.96

• /Et3N, followed by silica gel column chromatography, led to the triethylammonium salt of 2-N-Boc-aminoethylphosphinic acid 5 in 50 % yield. Alkylation of acid 5 with methyl chloroacetate in the presence of TMSCl and Et3N took five days at room temperature, and compound 6 as triethylammonium salt was

• obtained in 84% yield after silica gel purification. Removal of the Boc protecting group from 6 in the presence of trifluoroacetic acid in DCM at room temperature overnight, followed by cyclisation in boiling pyridine/triethylamine, led to 4-hydroxy-1,4-azaphosphinan-2,4-dione (7) in 84% yield. The free

• phosphinic acid 7 was further protected with benzyl alcohol by a procedure adopted from reference [67] using TBTU and Et3N in refluxing dichloroethane. Compound 8 was obtained in 65% yield after silica gel column chromatography. To synthesise a nucleobase for nucleosides Va and Vb, we first obtained

Light on the sustainable preparation of aryl-cored dibromides

• Fabrizio Roncaglia,
• Alberto Ughetti,
• Nicola Porcelli,
• Biagio Anderlini,
• Andrea Severini and
• Luca Rigamonti

Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95

• the addition was complete, the mixture was left under stirring for 1 h and 30 min. After the workup, operated as described previously, a brown slurry was obtained. Yield: 42%. The crude product was purified via column chromatography on silica gel 60, eluting with petroleum ether. The pure product

Spin and charge interactions between nanographene host and ferrocene

• Akira Suzuki,
• Yuya Miyake,
• Ryoga Shibata and
• Kazuyuki Takai

Beilstein J. Org. Chem. 2024, 20, 1011–1019, doi:10.3762/bjoc.20.89

• mesoporous silica (MCM-41) [18]. So, ferrocene is expected to exhibit strong host–guest interactions with a nanographene host through π–π stacking. Regarding ferrocene as a guest molecule for nanocarbon hosts, carbon nanotubes (CNTs) have been used to accommodate guest ferrocene molecules, where the amount

Enantioselective synthesis of β-aryl-γ-lactam derivatives via Heck–Matsuda desymmetrization of N-protected 2,5-dihydro-1H-pyrroles

• Arnaldo G. de Oliveira Jr.,
• Martí F. Wang,
• Rafaela C. Carmona,
• Danilo M. Lustosa,
• Sergei A. Gorbatov and
• Carlos R. D. Correia

Beilstein J. Org. Chem. 2024, 20, 940–949, doi:10.3762/bjoc.20.84

• products) were found to be somehow unstable when concentrated to dryness during work-up. We hypothesize that a possible cause of such instability might consist in the formation of a highly electrophilic iminium ion upon protonation of the hemiaminal ether by silica or glassware acidity and further

Synthesis and properties of 6-alkynyl-5-aryluracils

• Ruben Manuel Figueira de Abreu,
• Till Brockmann,
• Alexander Villinger,
• Peter Ehlers and
• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 898–911, doi:10.3762/bjoc.20.80

• was performed on Merck Silica gel 60 (particle size 63–200 μm). Solvents for extraction and column chromatography were distilled prior employment. Representative method for the preparation of starting materials 5-Bromo-6-chloro-1,3-dimethyluracil (2). Uracil 1 (22.9 mmol; 4.00 g) was dissolved in

Skeletal rearrangement of 6,8-dioxabicyclo[3.2.1]octan-4-ols promoted by thionyl chloride or Appel conditions

• Martyn Jevric,
• Julian Klepp,
• Johannes Puschnig,
• Oscar Lamb,
• Christopher J. Sumby and
• Ben W. Greatrex

Beilstein J. Org. Chem. 2024, 20, 823–829, doi:10.3762/bjoc.20.74

• , although 11a was sufficiently stable for filtration through a pad of silica. Applying these conditions and isolation protocols to all 3,3-disubstituted alcohols 10c–f gave moderate to excellent yields of the rearrangement products 11c–f as single stereoisomers. The reactions of alcohols 10b,d,e also gave

• sulfites were not intermediates in the reaction manifold. Furthermore, the isolation of some starting alcohols in the reactions of 10b and 10d following chromatography was attributed to hydrolysis of the corresponding dialkyl sulfite 13b and 13d on silica, a process that can be acid or base-catalysed [26

• during chromatography, and so an alternate method was developed to generate a single product by promoting the formation of the hemiacetal series 12a–f. Following the rearrangement reaction, chromatography of the chlorides using silica with 2% water added led to the isolation of 12a,c–f in good yield

Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• -workers [10][58]. They observed that silica gel and alumina, when thermally equilibrated (120 °C, 48 h), facilitated efficient hydrochlorinations when treated with HCl or reactive chlorides. A compelling demonstration of the potent role of silica gel is presented in Table 4. In the absence of silica gel

• , cycloheptene (61), when exposed to a concentrated solution of HCl in dichloromethane, did not show any reaction (Table 4, entry 1). Under the same conditions, in the presence of silica gel, they observed 97% conversion and a GC yield of 62% for chloride 62 (Table 4, entry 2). Further optimization identified

• and the surface area of the silica gel or alumina. Ethereal solvents were found to yield hydrochlorination reactions only with highly reactive alkenes, such as pinene. Subsequent studies revealed the need to adapt the hydrochlorination procedure for each substrate (e.g., Table 5). For instance, the

Isolation and structure determination of a new analog of polycavernosides from marine Okeania sp. cyanobacterium

• Kairi Umeda,
• Naoaki Kurisawa,
• Ghulam Jeelani,
• Tomoyoshi Nozaki,
• Kiyotake Suenaga and
• Arihiro Iwasaki

Beilstein J. Org. Chem. 2024, 20, 645–652, doi:10.3762/bjoc.20.57

• hexane. The aqueous MeOH portion was purified by reversed-phase column chromatography (ODS silica gel, MeOH/H2O), automated flash chromatography (hexane/EtOAc), and repeated reversed-phase HPLC to give polycavernoside E (1, 0.5 mg as a colorless oil). The isolation of compound 1 was directed by its

• based on HMBC and HMQC experiments. HRESIMS spectra were obtained on a Bruker timsTOF mass spectrometer. For reversed-phase column chromatography, ODS silica gel Cosmosil 75C18-OPN (Nacalai Tesque) was used. For medium pressure column chromatography, AFCS (Smart Flash AKROS, Yamazen) consisting of a

Chemical and biosynthetic potential of Penicillium shentong XL-F41

• Ran Zou,
• Xin Li,
• Xiaochen Chen,
• Yue-Wei Guo and
• Baofu Xu

Beilstein J. Org. Chem. 2024, 20, 597–606, doi:10.3762/bjoc.20.52

• extract was partitioned between EtOAc and H2O. The EtOAc fraction was chromatographed repeatedly over silica gel and reversed-phase high-performance liquid chromatography (RP-HPLC), resulting in the isolation of pure compounds 1–12 (Figure 2). According to literature reports of known compounds, some of

• IMS Q-Tof liquid chromatograph mass spectrometer. For NMR analysis, we utilized an AVANCE II 600 spectrometer, referencing residual solvent peaks at δH/δC 7.27/77.0 ppm in CDCl3 for chemical shift calibration. We utilized commercial silica gel from Yantai Xinnuo New Material Technology Co., Ltd

• EtOAc extracts were dried using a rotary evaporator to obtain the final EtOAc extract, which was stored at −80 °C until further isolation process. Compounds purification The EtOAc extract (3.5 g) obtained from the fermentation broth of XISR I medium underwent column chromatography on silica using a

A myo-inositol dehydrogenase involved in aminocyclitol biosynthesis of hygromycin A

• Michael O. Akintubosun and
• Melanie A. Higgins

Beilstein J. Org. Chem. 2024, 20, 589–596, doi:10.3762/bjoc.20.51

• . Reactions for thin-layer chromatography analysis were carried out using the same general reaction conditions reported above. Six μL of each reaction were spotted on the TLC silica gel 60 F254 (Sigma) and run with a solvent system containing butanol/ethanol/water 5:4:3. The TLC was stained using a solution

Synthesis and biological profile of 2,3-dihydro[1,3]thiazolo[4,5-b]pyridines, a novel class of acyl-ACP thioesterase inhibitors

• Jens Frackenpohl,
• David M. Barber,
• Guido Bojack,
• Birgit Bollenbach-Wahl,
• Ralf Braun,
• Rahel Getachew,
• Sabine Hohmann,
• Kwang-Yoon Ko,
• Karoline Kurowski,
• Bernd Laber,
• Rebecca L. Mattison,
• Thomas Müller,
• Anna M. Reingruber,
• Dirk Schmutzler and
• Andrea Svejda

Beilstein J. Org. Chem. 2024, 20, 540–551, doi:10.3762/bjoc.20.46

• -ynylcarbamoyl)-1,3-dioxolane-2-carboxamide [3] and FAM azide, 5-isomer (Broadpharm BP-22544, San Diego, CA) by click chemistry [29] and was purified by flash column chromatography on silica gel. Preemergence efficacy of 2,3-dihydro[1,3]thiazolo[4,5-b]pyridine-based FAT inhibitors 7b, 7c, and 13b as well as

A new analog of dihydroxybenzoic acid from Saccharopolyspora sp. KR21-0001

• Rattiya Janthanom,
• Yuta Kikuchi,
• Hiroki Kanto,
• Tomoyasu Hirose,
• Arisu Tahara,
• Takahiro Ishii,
• Arinthip Thamchaipenet and
• Yuki Inahashi

Beilstein J. Org. Chem. 2024, 20, 497–503, doi:10.3762/bjoc.20.44

• flowthrough fraction was adjusted to 3 with formic acid (FA) and chromatographed again on HP20 column. Now, 1 was retained in the resin and eluted by 50% MeOH with 0.05% FA. Then 1 was purified by silica gel and ODS column chromatography, and ethyl acetate extraction under acidic conditions. As the result of

• and extracted with ethyl acetate. The ethyl acetate layer was purified using a silica gel column (25 i.d. × 300 mm) by eluting with CHCl3/MeOH (100:0, 100:1, 100:2, 10:1, 1:1, and 0:100). The 10:1 fraction was purified with an ODS column (47 i.d. × 260 mm) by eluting with MeOH/H2O (0%, 10%, 20%, 30

Pseudallenes A and B, new sulfur-containing ovalicin sesquiterpenoid derivatives with antimicrobial activity from the deep-sea cold seep sediment-derived fungus Pseudallescheria boydii CS-793

• Zhen Ying,
• Xiao-Ming Li,
• Sui-Qun Yang,
• Hong-Lei Li,
• Xin Li,
• Bin-Gui Wang and
• Ling-Hong Meng

Beilstein J. Org. Chem. 2024, 20, 470–478, doi:10.3762/bjoc.20.42

• Discussion For chemical investigation, the solvent EtOAc was used to extract the fermentation culture of the fungus P. boydii CS-793 to afford an organic extract. Isolation and purification of the crude extract with a combination of column chromatography (CC) by Lobar LiChroprep RP-18, silica gel, Sephadex

• by Chromeleon software (version 6.80). LC–MS were obtained with a Bruker maXis plus Q-TOF. Column chromatography was carried out using commercially available silica gel (200–300 mesh, Qingdao Haiyang Chemical Co.), Lobar LiChroprep RP-18 (40–63 μm, Merck), and Sephadex LH-20 (Pharmacia). Thin-layer

• CC on silica gel eluting with a CH2Cl2/MeOH gradient (from 200:1 to 100:1) and then by preparative TLC (plate: 20 × 20 cm, developing solvents: ether/acetone 2:1) to afford compound 4 (8.6 mg). Fr. 5.4 (538 mg) was separated by CC on Si gel and Sephadex LH-20 (MeOH), after that compounds 1 (12.5 mg

Synthesis of 2,2-difluoro-1,3-diketone and 2,2-difluoro-1,3-ketoester derivatives using fluorine gas

• Alexander S. Hampton,
• David R. W. Hodgson,
• Graham McDougald,
• Linhua Wang and
• Graham Sandford

Beilstein J. Org. Chem. 2024, 20, 460–469, doi:10.3762/bjoc.20.41

• difluorinated product 5a in 85% isolated yield. Purification of 5a was achieved very readily by eluting the reaction mixture through a small quantity of silica gel with chloroform and evaporating the residual solvent to leave the crude product which could be further purified by recrystallization. Subsequently

• , a range of ethyl benzoylacetate derivatives was prepared (see Supporting Information File 1) [45][46] and successfully subjected to difluorination conditions (Table 3). Purification by column chromatography using the minimum amount of silica gel with chloroform as the eluent yielded 5c–g in high

Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives

• Nahed Ketata,
• Linhao Liu,
• Ridha Ben Salem and
• Henri Doucet

Beilstein J. Org. Chem. 2024, 20, 427–435, doi:10.3762/bjoc.20.37

• cartridges containing 40 μm irregular silica. General procedures General procedure for the palladium-catalyzed synthesis of fluoranthenes 1–18 via double C–H bond functionalization The reaction of 1,8-dibromonaphthalene (0.286 g, 1 mmol), (hetero)arene (1.5 mmol) and KOPiv (0.420 g, 3 mmol) in the presence

• of PdCl(C3H5)(dppb) (30.5 mg, 0.05 mmol) at 150 °C during 16 h in DMA (4 mL) under argon affords the coupling products 1–18 after evaporation of the solvent and purification on silica gel. Eluent EtOAc/heptane 1:9 for compounds 3–8, 10–18; heptane for compounds 1, 2, and 9. General procedure for the

• DMA (4 mL) under argon affords the coupling products 19–27 after evaporation of the solvent and purification on silica gel. Eluent EtOAc/heptane 1:9 for compounds 19–24; heptane for compounds 25 and 26; EtOAc/heptane 2:8 for compound 27. General procedure for the palladium-catalyzed synthesis of 9

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

• or Lewis acids as catalysts. In 2010, Shiri published a review, where the majority of the acidic catalysts that have been employed for the synthesis of these compounds were presented [12]. Since then, various alternative acids have been applied including protic acids, such as silica-bonded S-sulfonic

• acids, such as N-bromosuccinimide (NBS) [54], silica chloride [55], Ph3CCl [56], ZnO [57], La(NO3)3·6H2O [58], V(HSO4)3 [59], Cu(ClO4)2·6H2O [60], Fe/Al pillared clay [61], trimethylsilyl chloride (TMSCl) [62], BiCl3-loaded montmorillonite K10 [63][64][65][66][67], ZrO2-MgO [68] or CaO [69]. Silica gel

• facile recyclability, with the silica layer preventing the Fe3O4 from aggregation. The LPMNPs managed to provide impressive yields, while employing an amount of 2.5 mol % in water, with the help of conventional heating at 50 °C, which facilitated the organocatalytic process that required 1 to 1.5 hours

Additive-controlled chemoselective inter-/intramolecular hydroamination via electrochemical PCET process

• Kazuhiro Okamoto,
• Naoki Shida and
• Mahito Atobe

Beilstein J. Org. Chem. 2024, 20, 264–271, doi:10.3762/bjoc.20.27

• of 5 mA (3 F/mol, 57.9 C) through the CF anode (1 × 1 cm) and the Pt cathode (1 × 1 cm). The reaction mixture was concentrated in vacuo and Et2O (20 mL) was added. The resulting precipitate was removed by filtration through a short silica gel pad under reduced pressure. The filtrate was concentrated

• was removed by filtration through a short silica gel pad under reduced pressure. The filtrate was concentrated in vacuo and the resulting residue was subjected to 1H NMR spectroscopy or column chromatography. Application of amidyl radical species generated by PCET. (A) Effect of phosphate base on the

Chiral phosphoric acid-catalyzed transfer hydrogenation of 3,3-difluoro-3H-indoles

• Yumei Wang,
• Guangzhu Wang,
• Yanping Zhu and
• Kaiwu Dong

Beilstein J. Org. Chem. 2024, 20, 205–211, doi:10.3762/bjoc.20.20

• and the reaction mixture was stirred at room temperature for 3 h. After concentrating the mixture, the residue was purified by column chromatography on silica gel using a mixture of petroleum ether/ethyl acetate 30:1 (v/v) as the eluent to afford products 2. The yields were determined by 19F NMR

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• the stereoselectivity of sialylation, it is important to analyze anomeric ratio values (α/β) for the disaccharide fraction separated by size-exclusion chromatography since the retention values of different disaccharide anomers on silica gel may be surprisingly large and a minor isomer may be lost

• during purification by silica gel chromatography. On the other hand, NMR analysis of the crude reaction mixtures may be misleading due to possible overlap of the signals of H-3eq belonging both to disaccharide and monosaccharide derivatives sometimes present in such glycosylation mixtures. At low

• glycosylation reactions was distilled under argon over P2O5 and then over CaH2 and stored over molecular sieves (MS) 3 Å. Powdered MS 3 Å (Fluka) were activated before the reactions by heating at ≈220 °C in high vacuum for 6 h. Column chromatography was performed on silica gel 60 (40–63 μm, Merck). Gel

Synthesis of the 3’-O-sulfated TF antigen with a TEG-N₃ linker for glycodendrimersomes preparation to study lectin binding

• Mark Reihill,
• Hanyue Ma,
• Dennis Bengtsson and
• Stefan Oscarson

Beilstein J. Org. Chem. 2024, 20, 173–180, doi:10.3762/bjoc.20.17

• silica gel 60 F254. Visualisation was performed with UV-light (254 nm) fluorescence quenching, and/or by staining with an 8% H2SO4 dip (stock solution: 8 mL conc. H2SO4, 92 mL EtOH), ninhydrin dip (stock solution: 0.3 g ninhydrin, 3 mL AcOH, 100 mL EtOH) and/or ceric ammonium molybdate dip (stock

• solution: 25 g ammonium molybdate tetrahydrate, 0.5 g Ce(SO4)2, 50 mL H2SO4, 450 mL EtOH). Chromatography Silica gel flash chromatography was carried out using Davisil® LC60A (40–63 μm) silica gel or with automated flash chromatography systems, Buchi Reveleris® X2 (UV 200–500 nm and ELSD detection

• , Reveleris® silica cartiges 40 μm, Büchi Labortechnik AG®) and Biotage® SP4 HPFC (UV 200–500 nm, Biotage® SNAP KP-Sil 50 μm irregular silica, Biotage® AB). Instrumentation 1H NMR and 13C NMR spectra were recorded on Varian Inova spectrometers at 25 °C in chloroform-d (CDCl3), methanol-d4 (CD3OD), deuterium