Substituent-controlled construction of A₄B₂-hexaphyrins and A₃B-porphyrins: a mechanistic evaluation

• Seda Cinar,
• Dilek Isik Tasgin and
• Canan Unaleroglu

Beilstein J. Org. Chem. 2023, 19, 1832–1840, doi:10.3762/bjoc.19.135

• , Kieselgel 60, F254, Merck) with visualization under UV light. Products were purified by silica gel flash column chromatography (0.05–0.63 mm, 230–400 mesh ASTM, E.Merck). N-Tosylimines 2a–m and 5,10-bis(pentafluorophenyl)tripyrromethane (1) were synthesized according to the previously reported literature

• )tripyrromethane (1, 0.090 mmol) in CH2Cl2 (1.5 mL) and the mixture was stirred at rt for 4 h. Afterwards, DDQ (0.180 mmol) was added to this solution and stirred for another 2 h. The resulting solution was eluted through a short silica gel column with EtOAc and the solvent was removed under reduced pressure. The

• residue was purified by silica gel column chromatography (EtOAc/hexane 1:50) or preparative thin-layer chromatography on silica gel (Silica gel 60, F254, Merck) where applicable to obtain A3B-porphyrins and A4B2-hexaphyrins. Yields of porphyrins 3a–k were between 9–22% and the yields of hexaphyrins 4b–g,j

A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen

• Gyula Dargó,
• Dóra Erdélyi,
• Balázs Molnár,
• Péter Kisszékelyi,
• Zsófia Garádi and
• József Kupai

Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133

• achieved, for example, by immobilizing the catalysts to a solid support [15], e.g., silica gel [16][17][18], organic polymers [19][20][21], magnetic nanoparticles [22][23], or by membrane separation, e.g., using organic solvent nanofiltration (OSN) [24][25][26], which methods can be easily implemented in

• menthol. The reactions under pressure were carried out in a 150 mL pressure flask (Synthware Glass). Thin-layer chromatography (TLC) was performed using silica gel 60 F254 (Merck) plates. The spots of the materials on TLC plates were visualized by UV light at 254 nm. The reactions were monitored by TLC

Active-metal template clipping synthesis of novel [2]rotaxanes

• Cătălin C. Anghel,
• Teodor A. Cucuiet,
• Niculina D. Hădade and
• Ion Grosu

Beilstein J. Org. Chem. 2023, 19, 1776–1784, doi:10.3762/bjoc.19.130

• experimental data Commercially available reagents were used without further purification. Compounds 1 [43][47], 4 [48], 9 [49], 10 [44] and M2 [44] were synthesized according to procedures reported in the literature. Thin-layer chromatography (TLC) was performed on silica gel 60 coated aluminium F254 plates

• and visualized by UV irradiation at 254 nm. Preparative column chromatography was carried out using silica gel 60 (0.040–0.063 mm) from Merck. The NMR spectra were recorded on Bruker Avance 400 MHz or Bruker Avance 600 MHz spectrometers. Chemical shifts (δ) are reported in parts per million (ppm

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• chromatography over silica gel eluting with CH2Cl2/hexane 1:4 to give white solids (2.11 g, 87%). 1H NMR (600 MHz, CDCl3) δ 8.12 (d, J = 7.7 Hz, 2H), 7.40 (t, J = 7.8 Hz, 2H), 7.34 (d, J = 8.2 Hz, 2H), 7.28 (t, J = 8.0 Hz, 4H), 7.24 (d, J = 8.1 Hz, 2H), 7.21–7.07 (m, 15H); 13C NMR (151 MHz, CDCl3) δ 143.55

• was washed with water, brine, dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The crude product was then purified by column chromatography over silica gel eluting with CH2Cl2/hexane 3:7 to give compound 3 as white solid (928 mg, 41% over two steps). 1H NMR (600 MHz

• purified by column chromatography over silica gel eluting with CH2Cl2/hexane 3:7, followed by recrystallization from a CH2Cl2/methanol mixture to obtain TPECNz as red solid (396.0 mg, 58%). Mp > 360 °C; 1H NMR (600 MHz, CDCl3) δ 8.43 (s, 2H), 8.15 (td, J = 7.1, 3.5 Hz, 4H), 7.74 (dd, J = 8.3, 1.7 Hz, 2H

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

• using an Agilent 6230 LC/TOF mass spectrometer. HPLC was performed on a Hitachi HPLC system equipped with an L-2130 pump, an L-2200 autosampler, an L-2300 column oven, and an L-2455 diode array detector. Silica gel AP-300 (Toyota Kako), Sephadex LH-20 (GE Healthcare), and Cosmosil 75C18-OPN (Nacalai

• Tesque) were used for column chromatography (CC). Silica gel 60 F254 and RP-18 F254S (Merck) were used for TLC analysis. Plant material B. disticha was cultivated in the greenhouse of Setsunan University medicinal plant garden (Osaka, Japan) in September 2014. Taxonomic identification was performed by an

• were concentrated in vacuo to yield the ethyl acetate fraction (11.8 g) and n-butanol fraction (7.4 g), respectively. The ethyl acetate fraction was separated by silica gel CC with CHCl3/MeOH (stepwise gradient of 100:1, 50:1, 30:1, 20:1, 15:1, 10:1, 8:1, and 0:1, v/v) as the eluent. The fractions were

Cyclodextrins permeabilize DPPC liposome membranes: a focus on cholesterol content, cyclodextrin type, and concentration

• Ghenwa Nasr,
• Hélène Greige-Gerges,
• Sophie Fourmentin,
• Abdelhamid Elaissari and
• Nathalie Khreich

Beilstein J. Org. Chem. 2023, 19, 1570–1579, doi:10.3762/bjoc.19.115

• introduced a new phase to the membrane referred to as “the liquid-ordered” (Lo) alongside with the gel phase and the liquid-disordered phase [18]. Besides, CHOL is a major component of the so-called “lipid rafts” which are perceived as membrane domains rich in CHOL and sphingomyelin and involved in various

• . Triton X-100, sodium chloride (NaCl), and Sephadex G25 gel were purchased from Sigma-Aldrich, Belgium. Ammonium molybdate, hydrogen peroxide, potassium dihydrogen phosphate, sodium sulfite, sodium bisulfite, chloroform, and methanol were purchased from Sigma-Aldrich, Germany. Cholesterol and

• , 4 °C) and a molecular sieves chromatography (using a Sephadex G25 gel filtration column). A Tris HCl buffer (0.1 M, pH 7.4) containing 150 mM NaCl was used for elution and liposome storage. Exposure of SRB-loaded liposomes to CDs The concentration of DPPC was determined for each formulation

Lewis acid-promoted direct synthesis of isoxazole derivatives

• Dengxu Qiu,
• Chenhui Jiang,
• Pan Gao and
• Yu Yuan

Beilstein J. Org. Chem. 2023, 19, 1562–1567, doi:10.3762/bjoc.19.113

• TLC monitoring. Upon completion, the solution was cooled to room temperature and the solvent was removed under vacuum directly. The crude residue was purified by column chromatography on silica gel (ethyl acetate/petroleum ether 40:1) to afford product 3a with 87% yield. Natural products and drug

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

• ) profile, was scale up fermented to give 12 g of culture extract. This extract was subjected to a silica gel column chromatography to give several fractions, which were further purified over normal and reversed-phase HPLC to yield 2-ethyl-2,6-dihydroxy-5,7-dimethylbenzofuran-3-one (1), 3,9

• . Experimental General experimental procedures Column chromatography (60.4 cm length × 5.5 cm inner diameter) was carried out on silica gel 230–400 mesh (Merck). Analytical TLC was performed on Merck pre-coated silica gel 60 F254 plates, and spots were detected using ceric sulfate spray reagent and/or diluted

• of this extract was subjected to a silica gel (230–400 mesh) column chromatography using a stepwise gradient of CH2Cl2/MeOH (ranging from 0 to 100% of MeOH, v/v), to afford a total of 8 main series (A–H) obtained on the basis of TLC analyses. However, series A (2.5 g) obtained with pure CH2Cl2 and

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

• chromatography was performed using silica gel 60 (0.040–0.060 nm) purchased from Merck (Darmstadt, Germany). NMR spectra were recorded on a Bruker Avance I 500 MHz spectrometer and a Bruker Avance III HD 700 MHz Cryo spectrometer. Chemical shifts were referenced to the residual proton signal of C6D6 (δ = 7.16

α-(Aminomethyl)acrylates as acceptors in radical–polar crossover 1,4-additions of dialkylzincs: insights into enolate formation and trapping

• Angel Palillero-Cisneros,
• Paola G. Gordillo-Guerra,
• Fernando García-Alvarez,
• Olivier Jackowski,
• Franck Ferreira,
• Fabrice Chemla,
• Joel L. Terán and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2023, 19, 1443–1451, doi:10.3762/bjoc.19.103

• reduced pressure to provide the crude product which was then purified by column chromatography on silica gel. 2. Procedure for the air-promoted 1,4-addition of dialkylzinc reagents to α-(aminomethyl)acrylates (preparation of compounds 11–13, 14a–c, and 15a). In a Schlenk-tube under argon, the appropriate

• (MgSO4), and concentrated under reduced pressure to provide the crude product which was then purified by column chromatography on silica gel. 3. Procedure for the air-promoted tandem 1,4-addition–aldol reaction between dialkylzinc reagents, α-(aminomethyl)acrylates and carbonyl derivatives (preparation

• aq NH4Cl (5 mL) at 0 °C. The aqueous layer was extracted with CH2Cl2 (2×). The combined organic layer was washed (brine), dried (MgSO4), and concentrated under reduced pressure to provide the crude product which was then purified by column chromatography on silica gel. Air-promoted radical chain

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

• removed under vacuo. The residue was purified by chromatography on silica gel (n-hexane/ethyl acetate 100:1 to 5:1) to give pure compound 5d (243 mg, 69%) as a beige solid. Mp 118.2 °C; Rf 0.50 (n-hexane/ethyl acetate 10:1); 1H NMR (600 MHz, CDCl3) δ 3.68 (s, 3H), 7.02–7.07 (m, 1H), 7.17–7.20 (m, 1H

• organic phases were dried with anhydrous sodium sulfate, filtered, and the solvent was removed under reduced pressure. The residue was purified by chromatography on silica gel (n-hexane/ethyl acetate 20:1 to 5:1) to give compound 6 (184 mg, 42%) as a colorless solid. Mp 204.5 °C; Rf 0.35 (n-hexane/ethyl

• combined organic phases were dried (anhydrous sodium sulfate), filtered, and the solvent was removed under vacuo. The residue was purified by chromatography on silica gel (n-hexane/ethyl acetate 20:1 to 5:1) to give compound 8b (105 mg, 71%) as a colorless solid. Mp 150.8 °C (lit.: 157 °C [38]); Rf 0.58 (n

Visible-light-induced nickel-catalyzed α-hydroxytrifluoroethylation of alkyl carboxylic acids: Access to trifluoromethyl alkyl acyloins

• Feng Chen,
• Xiu-Hua Xu,
• Zeng-Hao Chen,
• Yue Chen and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2023, 19, 1372–1378, doi:10.3762/bjoc.19.98

• LEDs (λmax = 399 nm) for 7 h. After the reaction was complete, the reaction mixture was poured into water and extracted with EtOAc. The combined organic phase was separated and washed with brine, dried over Na2SO4, and concentrated under vacuum. The resulting residue was purified by silica gel flash

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

• alcohol. This step was achieved by the deprotonation of 21.3 followed by the reaction with 1-bromooctadecane. Compound 21.4 was purified by chromatography on silica gel followed by a recrystallization in acetone. Deprotonation of the secondary alcohol present in 21.4 followed by the addition of

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

• under reflux (for 5a) or in a Dean–Stark apparatus (for 4a). After completion (TLC), the reaction mixture was cooled, washed with brine, and dried. The toluene was removed and the residue was purified by column chromatography on silica gel (acetone/ether 8:2) to give the pure N-substituted imidazole 6a

• mL) was added. The mixture was washed with brine and dried. Finally, the solvent was removed and the residue was purified by column chromatography on silica gel, using acetone/ether as eluent, to give the pure imidazole derivative 8. Medicines containing an imidazole nucleus. Synthesis of N

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

• solvent by rotatory evaporation at reduced pressure, the residue was subjected to column chromatography (silicon gel, 300–400 mesh) with petroleum ether and ethyl acetate (v/v = 1:1) to give the pure product for analysis. Ethyl rel-(3R,3'S,4'R)-1,1''-dibenzyl-5,5''-dichloro-7',7'-dimethyl-2,2'',5'-trioxo

• mixture was heated at 50 °C for seven hours. After removing the solvent by rotatory evaporation at reduced pressure, the residue was subjected to column chromatography (silicon gel, 300–400 mesh) with petroleum ether and ethyl acetate (v/v = 4:1) to give the pure product for analysis. rel-(3R,3'S,4'R)-1,1

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

• on silica gel 60 F254 (pre-coated aluminium) sheets from Merck. General procedure for the synthesis of copper(II) benzo[f]chromeno[2,3-h]quinoxalinoporphyrins 3–8 To a solution of copper(II) 2,3-diamino-meso-tetraarylporphyrin (1; 0.131 mmol) in chloroform (20 mL), 2-hydroxynaphthalene-1,4-dione (2

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

• chromatography (silica gel, DCM/PE 1:5, v:v). Compound NI-PTZ-F was obtained as orange solid. Yield: 40 mg (15%); mp 136.2–137.2 °C; 1H NMR (CDCl3, 400 MHz) δ 8.87 (d, J = 7.63 Hz, 1H), 8.70 (d, J = 7.25 Hz, 1H), 8.60 (d, J = 8.51 Hz, 1H), 8.00 (d, J = 7.63 Hz, 1H), 7.77–7.81 (m, 1H), 7.29–7.35 (m, 4H), 7.11 (d

• . Synthesis of NI-PTZ-Ph NI-PTZ-Ph was synthesized by a reported method [11][71] similar to that of NI-PTZ-F. The crude product was purified by column chromatography (silica gel, DCM/PE 1:3, v:v). Compound NI-PTZ-Ph was obtained as orange solid. Yield: 243 mg (52%); mp 126.2–127.2 °C; 1H NMR (CDCl3, 400 MHz

• product was purified by column chromatography (silica gel, DCM/PE 1:3, v:v). The product was obtained as orange solid. Yield: 230 mg (80%); mp 100.2–101.5 °C; 1H NMR (CDCl3, 400 MHz) δ 8.87 (d, J = 7.63 Hz, 1H), 8.69 (d, J = 8.38 Hz, 1H), 8.58 (d, J = 8.50 Hz, 1H), 7.98 (d, J = 7.76 Hz, 1H), 7.75–7.79 (m

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

• methods were used to purify the extract, such as MCI gel CHP 20, silica gel column, vacuum liquid chromatography, and semi-preparative HPLC purification, to obtain pure compounds. A total of ten compounds, including five new eudesmane-type sesquiterpenoids (1–5), and five known compounds were identified

• isolated by other researchers in the future, who could consider our conclusions and choose other aspects of biological activity to study. Experimental General procedures NMR spectra were recorded on a Bruker AV-500 or AV-600 spectrometer with TMS as an internal standard. Silica gel (200–300 mesh; Qingdao

• Marine Chemical Inc., Qingdao, China), RP-18 silica gel (40–60 µm; Daiso Co., Tokyo, Japan), and MCI gel CHP 20P (75–150 µm, Mitsubishi Chemical Industries, Tokyo, Japan) were used for column chromatography. Optical rotations were measured on an Anton Paar MCP-100 digital polarimeter. UV and CD spectra

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• -substituted pyrrole in 60–80% yields in very short reaction times [76] (Scheme 23). To optimize the reaction conditions, several green protocols were used, among these sulfuric acid-immobilised on silica gel (SSA) catalyst under solvent-free conditions was chosen for the synthesis of these N-substituted

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• preliminary conditions, albeit in low yield (35% yield) and low regioselectivity (1:1) (Table 1, entry 1). No regiocontrol was observed; but remarkably, the regioisomers exhibited distinct retention factors on silica gel, allowing 11 and 12 to be isolated separately in good yield as single trans diastereomers

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

• mixture by silica gel column chromatography (Scheme 3). In the subsequent reaction of the α-brominated product 6c with nitrostyrene 2a in the presence of triethylamine, the complete consumption of 2a was confirmed, however, the reaction mixture was complicated, and the desired cyclopropane 1c was not

• , and the residual yellow oil was subjected to column chromatography on silica gel to afford ethyl 2-benzoyl-3-(4-methylphenyl)-4-nitrobutanoate (4f) [28] (eluted with hexane/ethyl acetate 95:5, 1.43 g, 4.02 mmol, 67%) as a pale-yellow oil. Major isomer 1H NMR (400 MHz, CDCl3) δ 0.92 (t, J = 7.2 Hz, 3H

• was stirred at room temperature for 14 h. The solution was subjected to column chromatography on silica gel to afford ethyl 4,5-dihydro-4-(4-methylphenyl)-5-nitro-2-phenylfuran-3-carboxylate (8f) (eluted with hexane/ethyl acetate 95:5, 53 mg, 0.15 mmol, 9%) as a pale-yellow oil, ethyl 1-benzoyl-2-(4

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, 789–799, doi:10.3762/bjoc.19.59

• chromatography (CC) was performed using macroporous adsorbent resin Amberlite TM XAD 16N (particle size 20–60 mesh, Rohm and Haas Company), MCI gel CHP 20P (particle size 75–150 μm, Mitsubishi Chemical Industries, Japan), RP-18 (particle size 40–60 μm; Daiso Co.), C-18 silica gel (particle size 40–60 μm; Daiso

• Co., Japan), Sephadex LH-20 (Amersham Biosciences), and YMC gel ODS-A-HG (particle size 40–60 μm; YMC Co. Japan). A Saipuruisi chromatograph with a semi-preparative high-pressure infusion pump (SP-5030) and a semi-preparative UV–vis dual wavelength detector (UV200) were utilized for RP–HPLC. A YMC

• ) utilizing a macroporous adsorbent resin column eluted with gradient aqueous MeOH (0–100%). Fr. E (180 g) was separated into ten parts (Fr. E1–Fr. E9, Fr. EA) using an MCI gel CHP 20P column (MeOH/H2O, 60–100%). Fr. E2 (2.0 g) was further divided into six portions (Fr. E21–Fr. E26) by Sephadex LH-20 (MeOH

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

• Sarot Cheenpracha,
• Ratchanaporn Chokchaisiri,
• Lucksagoon Ganranoo,
• Sareeya Bureekaew,
• Thunwadee Limtharakul and
• Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

• P. macropterum were extracted using MeOH to give a crude extract. After removal of the organic solvent, the extract was separated by repeated silica gel column chromatography as well as by Sephadex LH-20 to afford two new and one known cassane diterpenoids, identified as 12α,14β-dihydroxycassa-13(15

• ) in the deuterated solvents (CDCl3) using TMS as an internal standard. An Agilent 1290 infinity II/Q-TOFMS mass spectrometer was employed to acquire HRESI–TOF–MS spectra. Column chromatography (CC) was carried out on silica gel 60 (70–230 mesh, Merck, Darmstadt, Germany), and Sephadex LH-20 (GE

• Healthcare). Thin-layer chromatography (TLC) was performed on silica gel 60 F254 plates (Merck, Darmstadt, Germany) using precoated aluminum plates for analytical purposes. Plant material Fresh fruits of Pterolobium macropterum Kurz were collected from Song Khwae District, Nan Province, Thailand (GPS: 19

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

• Grédy Kiala Kinkutu,
• Catherine Louis,
• Myriam Roy,
• Juliette Blanchard and
• Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

• starting material had proved to be the most reactive imine in batch, leading, in the presence of 5 mol % of [Ru3(CO)12] and 3 equivalents of triethoxyvinylsilane in toluene at 150 °C after 5 h, to the alkylated aldehyde 2a with 62% yield, after purification on silica gel (Scheme 2) [21][39]. The flow

• ligand was completely consumed (monitored by TLC, ≈10 min). The solvent was then evaporated under reduced pressure. The remaining crude was purified by silica gel column chromatography using pentane as eluent, leading to 1.3 g of the desired complex as an orange solid (68% yield). 1H NMR (400 MHz, CDCl3

• chemistry, residence time 1 = 18 min, residence time 2 = 50 min. An aliquot of 0.5 mL of the product mixture was evaporated (93% conv., 77% NMR yield), and the crude was purified by silica gel column chromatography eluting with a mixture of cyclohexane/EtOAc 9:1 to give 38 mg of the desired product as an

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• stem wood, a fraction was obtained using a Sephadex LH-20 column by partition chromatography to afford two active fractions. One of the fractions was chromatographed on a silica gel column to give compound 1 (180 mg). The other fraction was again chromatographed on a Sephadex LH-20 column and the

• resulting active fraction was chromatographed on a silica gel column to afford a new fraction. Re-chromatography in a silica gel column using gradient elution afforded combretastatin D-2 (2, 5.8 mg) [17]. The general structures of combretastatins D-1 (1) and D-2 (2) were established by Pettit and Singh [16

• fractions were re-chromatographed on Sephadex LH-20 and the obtained fractions were further purified by silica gel column chromatography. One of the obtained fractions contained pure compound 3 (10.6 mg), while another fraction was further purified by silica gel column chromatography to give compound 4 (6.8