Synthesis and late stage modifications of Cyl derivatives

• Phil Servatius and
• Uli Kazmaier

Beilstein J. Org. Chem. 2022, 18, 174–181, doi:10.3762/bjoc.18.19

• of 11 could be separated by reversed-phase flash chromatography. It was obviously the C-terminal unusual amino acid which underwent epimerization under the reaction conditions, since already the Pfp ester 10 was partially epimerized, as determined later on. To access the allylglycine motif for

First total synthesis of hoshinoamide A

• Haipin Zhou,
• Zihan Rui,
• Yiming Yang,
• Shengtao Xu,
• Yutian Shao and
• Long Liu

Beilstein J. Org. Chem. 2021, 17, 2924–2931, doi:10.3762/bjoc.17.201

• the filtrate was concentrated in vacuo to give a brown oil which was purified by flash chromatography (n-hexanes/EA 2:1), affording tripeptide 8 (1.87 g, 95%) as a white foam. 1H NMR (400 MHz, methanol-d4) δ 7.59 (d, J = 8 Hz, 2H), 7.45 (d, J = 8 Hz, 2H), 7.21–6.96 (m, 10H), 5.52 (m, 1H), 4.81 (s, 2H

Biological properties and conformational studies of amphiphilic Pd(II) and Ni(II) complexes bearing functionalized aroylaminocarbo-N-thioylpyrrolinate units

• Samet Poyraz,
• Samet Belveren,
• Sabriye Aydınoğlu,
• Mahmut Ulger,
• Abel de Cózar,
• Maria de Gracia Retamosa,
• Jose M. Sansano and
• H. Ali Döndaş

Beilstein J. Org. Chem. 2021, 17, 2812–2821, doi:10.3762/bjoc.17.192

• silica gel 60 (230–400 mesh). Kieselgel columns were packed with silica gel GF254 (Merck 7730). Flash chromatography was carried out on handpacked columns of Merck silica gel 60 (0.040–0.063 mm). Melting points were determined on a Stuart SMP3 hot stage apparatus. The structurally most important peaks 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

• treated with acetic anhydride at room temperature. After workup by adding water and diethyl ether, the reaction mass was filtered and distilled until a residue was obtained. The colorless liquid compound 8 was obtained in 64% yield (as 6:1 mixture of anomers) after flash chromatography with 20% ethyl

• was devised for targeting specific receptors on the leukocytes membrane. The crucial N-glycosylation reaction between 1,3-oxathiolane precursor 45 and silylated cytosine was carried out using TiCl4 as a catalyst. The N-acylation of compound 92a was performed for flash chromatography, and further

α,γ-Dioxygenated amides via tandem Brook rearrangement/radical oxygenation reactions and their application to syntheses of γ-lactams

• Mikhail K. Klychnikov,
• Radek Pohl,
• Ivana Císařová and
• Ullrich Jahn

Beilstein J. Org. Chem. 2021, 17, 688–704, doi:10.3762/bjoc.17.58

• solution (5 drops), diluted with diethyl ether (10 mL), and filtered through a pad of silica gel, which was washed with a fresh portion of diethyl ether. The filtrate was evaporated, and the crude inhomogeneous mixture was purified by flash chromatography (gradient, hexanes/EtOAc 20:1 to 5:1) to give pure

• extracts were dried over MgSO4 and filtered. The filtrate was evaporated and the diastereomeric ratio was determined by 1H NMR spectroscopy. The crude mixture was purified by flash chromatography (gradient, hexanes/EtOAc 10:1 to 1:1) to give lactam trans-12. Dess–Martin oxidation of hydroxylactams 12

Synthesis of (Z)-3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones using an Eschenmoser coupling reaction

• Lukáš Marek,
• Lukáš Kolman,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2021, 17, 527–539, doi:10.3762/bjoc.17.47

• ATR diamond crystal (neat solid samples). Flash chromatography was performed using a Büchi Reveleris® X2 flash chromatography system equipped with a UV–vis/ELSD detector and Reveleris Flash pure cartridges (12–40 g, 35–45 μm, 53–80 Å) or puriFlash® Alumine N 32/63 µm cartridges (12 g). General

• ) in dry DMF (5 mL) was added. The mixture was stirred overnight at room temperature and then evaporated in vacuum. The residue was dissolved in DCM (40 mL), evaporated with neutral alumina (5 g) and submitted to preparative flash chromatography (silica gel or alumina cartridge; mobile phase and

• × 60 mL) and the combined organic layers were washed with water (2 × 40 mL) and brine (40 mL), dried with anhydrous Na2SO4 and evaporated. The solid residue was dissolved in methanol and filtered through a plug of Celite. The filtrate was evaporated with silica gel and submitted to preparative flash

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

• 0.1% (w/v) orcinol solution containing a sulfuric acid/ethanol/water 3:72.5:22.5, v/v/v mixture, followed by charring. Purification by column chromatography was performed using a Reveleris® flash chromatography automated system (Büchi) equipped with prepacked irregular silica gel 40–63 μm cartridges

• . The residue was recovered in ethyl acetate, and washed three times with saturated aqueous sodium hydrogen carbonate. The combined organic phases were dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. Flash chromatography (gradient of ethyl acetate in petroleum

• aqueous sodium hydrogen carbonate solution, and brine. The combined organic phases were dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure. Flash chromatography (gradient of ethyl acetate in petroleum ether from 0 to 50%) afforded 10 (516 mg, 2.47 mmol, 38%) as a solid

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7

• others were finally resolved in this work. Subsequently, the Hatakeyama team converted their authentic (+)-82 into the (R)- and (S)-MTPA Mosher esters which provided well-matched NMR data to Hale’s previous synthesis [60]. Upon further purification using flash chromatography, the Hatakeyama team re

Deoxyfluorination of acyl fluorides to trifluoromethyl compounds by FLUOLEAD^®/Olah’s reagent under solvent-free conditions

• Yumeng Liang,
• Akihito Taya,
• Zhengyu Zhao,
• Norimichi Saito and
• Norio Shibata

Beilstein J. Org. Chem. 2020, 16, 3052–3058, doi:10.3762/bjoc.16.254

• flash chromatography (n-hexane) to afford the title compounds. Ratios of CF3-containing drugs in marketed fluoro-pharmaceuticals and registered fluoro-agrochemicals in the world. Selected examples of CF3-containing biologically active molecules. Transformation of acyl fluorides to trifluoromethyl

Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate

• Stéphane Menuel,
• Sébastien Saitzek,
• Eric Monflier and
• Frédéric Hapiot

Beilstein J. Org. Chem. 2020, 16, 2598–2606, doi:10.3762/bjoc.16.211

• every 3 cycles to limit agglomeration of the powder. The resulting powder was purified by flash chromatography on silica gel using acetonitrile/water 9:1 to 8:2 (v/v) as mobile phase. Isolated yield 21% (364 mg). All runs were performed at least twice in order to ensure reproducibility. X-ray powder

Selective preparation of tetrasubstituted fluoroalkenes by fluorine-directed oxetane ring-opening reactions

• Clément Q. Fontenelle,
• Thibault Thierry,
• Romain Laporte,
• Emmanuel Pfund and
• Thierry Lequeux

Beilstein J. Org. Chem. 2020, 16, 1936–1946, doi:10.3762/bjoc.16.160

• was slow at 20 °C and did not progress beyond 50% conversion even after the addition of excess LiBH4. After purification by flash chromatography starting lactone 21 was obtained in 49% yield and the desired diol 22 in 47% yield. When the reaction was carried out in refluxing THF, a complete conversion

Three new O-isocrotonyl-3-hydroxybutyric acid congeners produced by a sea anemone-derived marine bacterium of the genus Vibrio

• Dandan Li,
• Enjuro Harunari,
• Tao Zhou,
• Naoya Oku and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1869–1874, doi:10.3762/bjoc.16.154

• gradient of MeOH in CHCl3 and octadecyldimethylsilyl (ODS) flash chromatography with elution by acidic aqueous MeCN. One of the midpolar fractions was purified by reversed-phase HPLC to give 1 (1.5 mg), 2 (11.2 mg), 3 (4.3 mg), and 4 (135.6 mg) from a 3 L culture. The 1H NMR spectra of 1–4 similarly showed

Nonenzymatic synthesis of anomerically pure, mannosyl-based molecular probes for scramblase identification studies

• Giovanni Picca,
• Markus Probst,
• Simon M. Langenegger,
• Oleg Khorev,
• Peter Bütikofer,
• Anant K. Menon and
• Robert Häner

Beilstein J. Org. Chem. 2020, 16, 1732–1739, doi:10.3762/bjoc.16.145

• over MgSO4, and the volatile components were removed under reduced pressure. The yellowish residue (crude product) was purified by flash chromatography over silica gel, with a mixture of n-hexane/ethyl acetate 3:2, v/v as eluent. The fractions containing the product (Rf = 0.22 in n-hexane/ethyl acetate

• under argon. The crude product was then directly purified by flash chromatography using ethyl acetate/n-hexane 1:1, v/v + 2% triethylamine. The fractions containing the product (Rf = 0.40) were combined, and the solvents were removed under reduced pressure on a rotary evaporator. The product was

• under reduced pressure. The resulting material was then dissolved in DCM and purified by flash chromatography on silica gel using ethyl acetate/n-hexane 7:3, v/v as eluent. The fractions containing the intermediate α-4Ac-Man-P-Cit-BZP-yne (Rf = 0.33 using the same solvent system as for the column) were

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• diastereoselectivity [57][58]. In this work, Si−O tethered 1,7-enynes underwent the PKR after treatment with 1.05 equiv of Co2(CO)8 using 4-fluorobenzyl(methyl)sulfide (4-FBnSMe) as an additive, which is commercially available and can be easily recovered by flash chromatography. Under the aforementioned conditions

Rearrangement of o-(pivaloylaminomethyl)benzaldehydes: an experimental and computational study

• Csilla Hargitai,
• Györgyi Koványi-Lax,
• Tamás Nagy,
• Péter Ábrányi-Balogh,
• András Dancsó,
• Gábor Tóth,
• Judit Halász,
• Angéla Pandur,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2020, 16, 1636–1648, doi:10.3762/bjoc.16.136

• ). Purifications by flash chromatography were performed applying a Teledyne Isco Combiflash® Rf system (Thousand Oaks, CA, USA) with Redisep® Rf silica flash columns using a hexane–EtOAc solvent system. The preparative HPLC separation was carried out using a Merck LaPrep Sigma LP1200 pump and a Merck LaPrep P314

• solution (5%, 7 mL) and DCM (4 mL) were added. The aqueous layer was extracted with DCM (2 × 4 mL). The combined organic layer was dried over MgSO4. The solvent was evaporated and the residue purified by flash chromatography (5–30% EtOAc in hexane). The corresponding fractions were collected, evaporated

• solution (5%, 7 mL) and DCM (4 mL) were added. The aqueous layer was extracted with DCM (2 × 4 mL). The combined organic layer was dried over MgSO4. The solvent was evaporated and the residue purified by flash chromatography (5–30% EtOAc in hexane). The corresponding fractions were collected, evaporated

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

• thioketone 8 and a catalytic amount (ca. 5 mg) of Sc(OTf)3 was added to the stirred solution. The mixture was stirred at room temperature for 1 h. The progress of the reaction was monitored by TLC. The solvent was evaporated in vacuo and the crude mixture was purified by flash chromatography using

Synthesis of pyrrolidinedione-fused hexahydropyrrolo[2,1-a]isoquinolines via three-component [3 + 2] cycloaddition followed by one-pot N-allylation and intramolecular Heck reactions

• Xiaoming Ma,
• Suzhi Meng,
• Xiaofeng Zhang,
• Qiang Zhang,
• Shenghu Yan,
• Yue Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2020, 16, 1225–1233, doi:10.3762/bjoc.16.106

• ), K2CO3 (1 mmol) and NaOAc (0.5 mmol) in MeCN (3 mL) at 105 °C for 3 h under nitrogen atmosphere. After aqueous work up, the crude product was purified by flash chromatography to afford product 9 or 11. General procedure for the synthesis of pyrrolo[2,1-a]isoquinolines 12 To a solution of pyrrolidine

• -allylation intermediate which was then used for the Heck reaction with Pd(OAc)2 (10 mol %), PPh3 (20 mol %), K2CO3 (2 equiv) and NaOAc (1 equiv) in MeCN (3 mL) at 105 °C for 3 h under nitrogen atmosphere. After aqueous work-up, the crude product was purified by flash chromatography to afford product 12

Palladium-catalyzed regio- and stereoselective synthesis of aryl and 3-indolyl-substituted 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones

• Valeria Nori,
• Antonio Arcadi,
• Armando Carlone,
• Fabio Marinelli and
• Marco Chiarini

Beilstein J. Org. Chem. 2020, 16, 1084–1091, doi:10.3762/bjoc.16.95

• , and solvents were commercially available and were used as purchased. The reaction products were purified by flash chromatography on silica gel by elution with n-hexane/EtOAc mixtures. Compounds 1a [44], 1b,c [41], 1d [45], 1e [46] and 5a–c [47] are known products and were identified by comparison of

• , dried over Na2SO4 and concentrated under reduced pressure. The residue was purified by flash chromatography (silica gel, n-hexane/EtOAc, 65:35 v/v) to afford 1-(4-(3-(benzylamino)prop-1-yn-1-yl)phenyl)ethanone (1f, 385.0 mg, 85%). Typical procedure for the preparation of N-benzyl-2-iodobenzamides (2a–f

• starting propargylamine (monitored by TLC). Then the reaction mixture was diluted with ethyl acetate, washed with a solution of NH4Cl (0.5 M), dried over Na2SO4 and concentrated under reduced pressure. The residue was purified by flash chromatography (silica gel, n-hexane/EtOAc) to afford the N-benzyl-2

Pd-catalyzed asymmetric Suzuki–Miyaura coupling reactions for the synthesis of chiral biaryl compounds with a large steric substituent at the 2-position

• Yongsu Li,
• Bendu Pan,
• Xuefeng He,
• Wang Xia,
• Yaqi Zhang,
• Hao Liang,
• Chitreddy V. Subba Reddy,
• Rihui Cao and
• Liqin Qiu

Beilstein J. Org. Chem. 2020, 16, 966–973, doi:10.3762/bjoc.16.85

• mixture was cooled to room temperature and water was added. Then, the reaction mixture was extracted with ethyl acetate and the organic layer was dried over anhydrous Na2SO4 and concentrated under reduced pressure to obtain the crude product. The crude product was purified by flash chromatography using

Efficient synthesis of dipeptide analogues of α-fluorinated β-aminophosphonates

• Marcin Kaźmierczak and
• Henryk Koroniak

Beilstein J. Org. Chem. 2020, 16, 756–762, doi:10.3762/bjoc.16.69

• % v/v) was added. The solution was stirred under an atmosphere of hydrogen at room temperature for 3 days. After this time the catalyst was filtered off (Celite), the solvent was evaporated and the crude product was purified using flash chromatography (chloroform/methanol 100:0, v/v chloroform

• product was purified by flash chromatography (n-hexane/ethyl acetate 60:40 → 50:50). EDCI/HOBt conditions: To a cooled (0 °C) solution of amine 13 (1.05 equiv) in DMF, Boc-Phe-OH (1 equiv), TEA (1 equiv), HOBt (1.3 equiv) and EDCI (1.25 equiv) were added. Stirring was continued at this temperature for 30

• was purified by flash chromatography (n-hexane/ethyl acetate 60:40 → 50:50). EDCI/OxymaPure conditions: Boc-Phe-OH (1 equiv), OxymaPure (1.1 equiv), and EDCI (1.1 equiv) were mixed in DMF at 0 °C under an argon atmosphere. The reaction mixture was stirred for 5 min at 0 °C to preactivate the acid and

Combination of multicomponent KA² and Pauson–Khand reactions: short synthesis of spirocyclic pyrrolocyclopentenones

• Riccardo Innocenti,
• Elena Lenci,
• Gloria Menchi and
• Andrea Trabocchi

Beilstein J. Org. Chem. 2020, 16, 200–211, doi:10.3762/bjoc.16.23

• mixture was heated under microwave irradiation to 100 °C for 2 h. Then, EtOAc was added and the organic phase was washed with 5% NH4OH (3 × 20 mL) and brine. The organic phase was dried with Na2SO4 and concentrated under reduced pressure. The crude product was purified by flash chromatography using the

• . The organic phase was washed with 1 M HCl (3 × 20 mL), satd. Na2CO3 (3 × 20 mL) and brine. The organic phase was dried over Na2SO4 and concentrated under reduced pressure. The crude product was purified by flash chromatography using the indicated solvent mixture as eluent. General procedure for the

• stirred at 70 °C until disappearance of the starting material as monitored by TLC. Then, the mixture was filtered on Celite and concentrated under reduced pressure. The crude product was purified by flash chromatography using the indicated solvent mixture as eluent. Molecular modelling. Calculations were

Allylic cross-coupling using aromatic aldehydes as α-alkoxyalkyl anions

• Akihiro Yuasa,
• Kazunori Nagao and
• Hirohisa Ohmiya

Beilstein J. Org. Chem. 2020, 16, 185–189, doi:10.3762/bjoc.16.21

• were removed under reduced pressure, GPC (EtOAc) followed by flash chromatography on silica gel (0–1% EtOAc/hexane) gave product 3aa in 64% isolated yield (45.7 mg, 0.13 mmol). Our strategy. Allylic cross-coupling using aldehydes as α-alkoxyalkyl anions. Substrate scope and reaction conditions. a

Extension of the 5-alkynyluridine side chain via C–C-bond formation in modified organometallic nucleosides using the Nicholas reaction

• Renata Kaczmarek,
• Dariusz Korczyński,
• James R. Green and
• Roman Dembinski

Beilstein J. Org. Chem. 2020, 16, 1–8, doi:10.3762/bjoc.16.1

• product and purification by flash chromatography (2:1→3:2 petroleum ether/EtOAc) afforded 6a as a red-brown oil (0.0110 g, 16.3 μmol, 55%). 1H NMR (500 MHz, CDCl3) δ 8.85 (br s, 1H), 7.72 (s, 1H), 6.24 (dd, J = 8.0 Hz, 5.4 Hz, 1H), 5.93 (m, 1H), 5.22 (d, J = 6.3 Hz, 1H), 5.15 (d, J = 17.2 Hz, 1H), 5.05 (d

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• (5.00 mL), the solution was extracted with CH2Cl2 (3 × 50.0 mL). The combined organic layers were dried (anhydrous MgSO4) and the solvent was removed in vacuo. The residue was purified by flash chromatography on silica gel (n-hexane/EtOAc 12:1 to 5:1 to 0:1) and washed with hot ethanol (5 mL) to give

• purified by flash chromatography on silica gel (n-hexane/EtOAc 5:1 to 1:1 to 0:1) and washed with hot ethanol (2.00 mL) and compound 6c (37.0 mg, 12%) was obtained as deep purple solid. Mp 224–253 °C; 1H NMR (300 MHz, CDCl3) δ 3.10 (s, 6H), 6.69 (s, 1H), 6.69–6.75 (m, 2H), 7.51–7.58 (m, 3H), 7.67–7.73 (m

• solution was extracted with CH2Cl2 (3 × 50.0 mL). The combined organic layers were dried (anhydrous MgSO4) and the solvent was removed in vacuo. The residue was purified by flash chromatography on silica gel (n-hexane/EtOAc 5:1 to 1:1 to 0:1) and washed with hot ethanol (5.00 mL) to furnish compound 8a

Acid-catalyzed rearrangements in arenes: interconversions in the quaterphenyl series

• Sarah L. Skraba-Joiner,
• Carter J. Holt and
• Richard P. Johnson

Beilstein J. Org. Chem. 2019, 15, 2655–2663, doi:10.3762/bjoc.15.258

• minutes. After cooling, products were isolated by careful neutralization with saturated aqueous NaHCO3 and extraction with dichloromethane. The crude product mixture was purified by flash chromatography then analyzed using 1H NMR. The presence of oligomeric material was assessed on crude isolated product

• extracted with DCM. The organic extract was washed with water and brine and dried with Na2SO4. The crude product was purified by flash chromatography with hexanes to yield o,p’-quaterphenyl as a white solid (0.55 g, mp 107–109 °C, lit 117–120 °C, 90% yield). 1H NMR (400 MHz, CDCl3) δ 7.61–7.57 (m, 2H), 7.50

• Na2SO4. The crude product was purified by flash chromatography with hexanes to yield o,m’-quaterphenyl as a white solid (0.085 g, mp 84–86 °C, lit 90–91 °C, 33% yield). 1H NMR (400 MHz, CDCl3) δ 7.52–7.47 (m, 1H), 7.47–7.40 (m, 4H), 7.38–7.29 (m, 6H), 7.29–7.26 (m, 1H), 7.26–7.22 (m, 3H), 7.21–7.15 (m