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

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

• Vânia F. Pais,
• Tristan Neumann,
• Ignacio Vayá,
• M. Consuelo Jiménez,
• Abel Ros and
• Uwe Pischel

Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254

• -brown solution was kept under argon. 1-(4'-Methoxy-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-[1,1'-binaphthalen]-4-yl)isoquinoline (16) Following the above described general procedure for the Ir-catalyzed borylation starting from 12 (85 mg, 0.21 mmol) and after flash chromatography on silica gel

• borylation starting from 13 (95 mg, 0.25 mmol) and after flash chromatography on silica gel (n-hexane/EtOAc 4:1), 17 was obtained as light-yellow foam (105 mg, 83% yield). NMR spectra recorded at 25 °C showed a ca. 0.45:0.55 diastereomeric mixture of atropisomers. To simplify the spectra the measurements

• )naphthalen-1-yl)isoquinoline (19) Following the above described general procedure for the Ir-catalyzed borylation starting from 15 (84 mg, 0.21 mmol) and after flash chromatography on silica gel (toluene/EtOAc 20:1), 19 was obtained as a yellow foam (100 mg, 72% yield). NMR spectra recorded at 25 °C showed a

Chemical synthesis of the pentasaccharide repeating unit of the O-specific polysaccharide from Escherichia coli O132 in the form of its 2-aminoethyl glycoside

• Debasish Pal and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2019, 15, 2563–2568, doi:10.3762/bjoc.15.249

• also a thioglycoside, only the donor thioglycoside was activated in the NIS-catalyzed activation because of the higher reactivity of the furanosyl donor having benzyl protections [24][25]. The mixture of α-linked and β-linked disaccharides was separated by flash chromatography to yield 59% pure α

Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene

• Anna Kmieciak and
• Marek P. Krzemiński

Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242

• solution was filtered, the solvent evaporated on a rotary evaporator and the product was purified by flash chromatography on silica gel (dichloromethane/diethyl ether 10:90). Phosphine oxide 22 (0.825 g, 56%) was obtained as an oil. In a second oxidation procedure, methanol (5 mL) and a 3 M solution of

• brine (5 mL). After drying the solution with anhydrous magnesium sulfate and filtration, the solvent was evaporated and the product was purified by flash chromatography on silica gel (hexane/ethyl acetate 80:20). Phosphine 23 (0.131 g, 62%) was obtained as a colorless oil. 1H NMR (700 MHz, CDCl3) δ 0.93

Effect of ring size on photoisomerization properties of stiff stilbene macrocycles

• Sandra Olsson,
• Óscar Benito Pérez,
• Magnus Blom and
• Adolf Gogoll

Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233

• precoated silica gel 60 F254 plates, visualized with UV light and Hannessian's stain (5% ammonium molybdate, 1% cerium sulfate and 10% sulfuric acid in water). Flash chromatography (CC) was performed over Matrex silica gel (60 Å, 35–70 µm) on a regular column or on a Grace Reveleris X2 Flash chromatography

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

• Christoph W. Grathwol,
• Nathalie Wössner,
• Sören Swyter,
• Adam C. Smith,
• Enrico Tapavicza,
• Robert K. Hofstetter,
• Anja Bodtke,
• Manfred Jung and
• Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

• ionization single quadrupole MS (LCMS-2020) controlled by Shimadzu LabSolution software (Version 5.91). Chromatographic purification of products was performed by flash chromatography on silica gel (20–45 µm, Carl Roth) applying pressured air up to 0.8 bar. NMR spectra were recorded on a Bruker Avance III

Bipolenins K–N: New sesquiterpenoids from the fungal plant pathogen Bipolaris sorokiniana

• Chin-Soon Phan,
• Hang Li,
• Simon Kessler,
• Peter S. Solomon,
• Andrew M. Piggott and
• Yit-Heng Chooi

Beilstein J. Org. Chem. 2019, 15, 2020–2028, doi:10.3762/bjoc.15.198

• a light-yellow crude extract (205 mg), which was fractionated on a Reveleris flash chromatography (Grace) using gradient mode of H2O/MeOH equipped with the flash cartridge, UV and evaporative light scattering detector. The resulting fractions were further purified by RP-HPLC on gradient mode of H2O

Isolation and characterisation of irinans, androstane-type withanolides from Physalis peruviana L.

• Annika Stein,
• Dave Compera,
• Bianka Karge,
• Mark Brönstrup and
• Jakob Franke

Beilstein J. Org. Chem. 2019, 15, 2003–2012, doi:10.3762/bjoc.15.196

• /MeOH (3:1) and divided into fractions soluble in petroleum ether, chloroform, and n-butanol, respectively. The chloroform fraction was further separated by flash chromatography on a C18 stationary phase, resulting in three major subfractions F1–F3. Final purification by preparative HPLC followed by NMR

• ether fraction, 386 mg CHCl3 fraction and 1174 mg n-BuOH fraction. The CHCl3 fraction was separated via reversed-phase flash chromatography (Biotage SNAP KP-C18-HS 30 g column) with a H2O/MeOH gradient. Samples were adsorbed onto Celite under reduced pressure for dry loading. A gradient from 30% to 95

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• even after using sub-stoichiometric quantities in the reaction. Attempted purification via alumina flash chromatography returned material that was assigned as the triazolium chloride salt (i.e., Cl– salt of triazolium 12; based on chemical shifts in the 1H and 13C NMR that were consistent with a

Vicinal difunctionalization of alkenes by four-component radical cascade reaction of xanthogenates, alkenes, CO, and sulfonyl oxime ethers

• Shuhei Sumino,
• Takahide Fukuyama,
• Mika Sasano,
• Ilhyong Ryu,
• Antoine Jacquet,
• Frédéric Robert and
• Yannick Landais

Beilstein J. Org. Chem. 2019, 15, 1822–1828, doi:10.3762/bjoc.15.176

• obtained on a JASCO FT/IR-4100 spectrometer; absorptions were reported in reciprocal centimeters. High-resolution mass spectra were recorded on a JEOL MS700 spectrometer or Exactive Plus EMR (Thermo Fisher Scientific). The products were purified by flash chromatography on silica gel (Kanto Chem. Co. Silica

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• pyrrolidin-2-ones (3S,4R,5R,1'R)-183b (by crystallization from cold ethanol) and (3R,4S,5R,1'R)-183b (by flash chromatography). After reduction and hydrogenolysis they were converted into 1,4-dideoxy-1,4-imino-ᴅ-arabinitol and ((2R,3R,4R)-182) and 1,4-dideoxy-1,4-imino-ᴅ-xylitol ((2R,3S,4S)-182

An azobenzene container showing a definite folding – synthesis and structural investigation

• Abdulselam Adam,
• Saber Mehrparvar and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2019, 15, 1534–1544, doi:10.3762/bjoc.15.156

• -layer plates. Flash chromatography was carried out on silica gel 60 (230–400 mesh). 1H and 13C NMR spectra were measured with an Avance HD 600 spectrometer. All chemical shifts (δ) are given in ppm. The spectra were referenced to the peak for the protium impurity in the deuterated solvents indicated in

One-pot activation–alkynylation–cyclization synthesis of 1,5-diacyl-5-hydroxypyrazolines in a consecutive three-component fashion

• Christina Görgen,
• Katharina Boden,
• Guido J. Reiss,
• Walter Frank and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 1360–1370, doi:10.3762/bjoc.15.136

• acids 1, oxalyl chloride, arylacetylenes 2, and hydrazides 4 were reacted in 1,4-dioxane and in the presence of catalytic amounts of copper(I) iodide in a one-pot activation–alkynylation–cyclization sequence to give 1,5-diacyl-5-hydroxypyrazoline 5 after flash chromatography on silica gel in moderate to

• dried with anhydrous sodium sulfate and the solvents were removed in vacuo. The crude product was adsorbed on celite© and purified by flash chromatography on silica gel (petroleum ether 40–60 °C/ethyl acetate 5:1) to give analytically pure 1,5-dibenzoyl-5-hydroxy-3-phenylpyrazoline (5b, 291 mg, 78%) as

Bambusuril analogs based on alternating glycoluril and xylylene units

• Tomáš Lízal and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2019, 15, 1268–1274, doi:10.3762/bjoc.15.124

• referenced to solvent residual peaks [19], the coupling constants (J) are reported in hertz (Hz). The multiplicities of signals are reported as singlet (s), doublet (d), triplet (t), multiplet (m). The flash chromatography was performed on a Büchi Reveleris PREP Purification System using RP C18 40g

• evaporated under reduced pressure and precipitated solid material was filtered off. The crude product was dried under vacuum. The crude product was purified by GRACE flash chromatography using a C-18 reversed-phase cartridge and acetonitrile/water as mobile phase. The sample (350 mg of crude product) was

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• using an encapsulated solvent purification system and were further dried over 4 Å molecular sieves. The evolution of reactions was monitored by analytical thin-layer chromatography using silica gel 60 F254 precoated plates. Flash chromatography was performed employing 230–400 mesh silica using the

Towards the preparation of synthetic outer membrane vesicle models with micromolar affinity to wheat germ agglutinin using a dialkyl thioglycoside

• Dimitri Fayolle,
• Nathalie Berthet,
• Bastien Doumeche,
• Olivier Renaudet,
• Peter Strazewski and
• Michele Fiore

Beilstein J. Org. Chem. 2019, 15, 937–946, doi:10.3762/bjoc.15.90

• of 1a (47 mg, 0.24 mmol, 3 equiv), 2a (11.2 mg, 0.08 mmol, 1 equiv) and DPAP (7.71 mg, 0.024 mmol, 0.3 equiv) in MeOH (660 μL) was irradiated at room temperature for 30 min and then concentrated. The residue was purified by silica flash chromatography (gradient: 100:0–80:20 CHCl3/MeOH v/v). Yield: 77

• , 0.025 mmol, 0.3 equiv) in DMF (1 mL) was irradiated at room temperature for 30 min and then concentrated. The residue was purified by silica flash chromatography (gradient: 100:0–80:20 CHCl3/MeOH v/v). Yield: 55% (20.3 mg, 0.047 mmol). Chemical analyses are in agreement with what was previously reported

• [44]. Compound 5: A stirred solution of glycosyl thiol 1b (49.8 mg, 0.21 mmol, 3 equiv), 2b (13.7 mg, 0.07 mmol, 1 equiv) and DPAP (5.1 mg, 0.02 mmol, 0.3 equiv) in DMF (660 μL) was irradiated at room temperature for 30 min and then concentrated. The residue was purified by silica flash chromatography

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• concentrated under reduced pressure. The crude mixtures were then purified by flash chromatography using pentane/diethyl ether as eluent. General procedure for the combined carbocupration/oxidation sequence The reaction was performed on a 1 mmol scale. To a suspension of CuCN (2 equiv) in 8 mL of Et2O was

• solution of NH4Cl/NH4OH (2:1). The aqueous layer was extracted twice with Et2O and the combined organic phases were washed with brine, dried over MgSO4, filtered, and concentrated under reduced pressure. Crude mixtures were then purified by flash chromatography using pentane/diethyl ether as eluent

Efficient synthesis of 4-substituted-ortho-phthalaldehyde analogues: toward the emergence of new building blocks

• Clémence Moitessier,
• Ahmad Rifai,
• Pierre-Edouard Danjou,
• Isabelle Mallard and
• Francine Cazier-Dennin

Beilstein J. Org. Chem. 2019, 15, 721–726, doi:10.3762/bjoc.15.67

• without further purification. Microwave-assisted organic synthesis was carried out using a 400 W Biotage initiator oven. Samples were placed in a sealed vial and irradiated with a temperature control. Automated flash chromatography was performed on a Puriflash 430 (Interchim) incorporating a quaternary

• then purified by flash chromatography using a SiO2 cartridge (80 g) with a gradient of hexane/AcOEt from 2:1 to 1:1 (TLC hexane/AcOEt 2:1 Rf = 0.4). Pure 4,5-dihydroisobenzofuran-5-ol (3) was obtained as a yellow oil (12.0 g, 85%). 1H NMR (400 MHz, CDCl3) δ 7.31 (s, 1H), 7.19 (s, 1H), 6.51 (d, J = 9.8

• . The liquid phase was dried over MgSO4 and concentrated under reduced pressure to obtain a residue which was purified by two successive flash chromatography runs. The first one was run on 100% DCM mobile phase in order to eliminate DDQ residue (Rf = 0.9) and the second with ethyl acetate/hexane (3:1

Dirhodium(II)-catalyzed [3 + 2] cycloaddition of N-arylaminocyclopropane with alkyne derivatives

• Wentong Liu,
• Yi Kuang,
• Zhifan Wang,
• Jin Zhu and
• Yuanhua Wang

Beilstein J. Org. Chem. 2019, 15, 542–550, doi:10.3762/bjoc.15.48

• backfilling the tube with argon three times, cyclopropylamine (1 mmol) was added. The reaction mixture was stirred at room temperature for 24 hours. After the reaction was complete, the mixture was concentrated and the residue was purified by flash chromatography to obtain the desired allylic amine