Design and synthesis of a bis-macrocyclic host and guests as building blocks for small molecular knots

• Elizabeth A. Margolis,
• Rebecca J. Keyes,
• Stephen D. Lockey IV and
• Edward E. Fenlon

Beilstein J. Org. Chem. 2020, 16, 2314–2321, doi:10.3762/bjoc.16.192

• reaction with ethylene carbonate using a modified literature procedure (see Supporting Information File 1). Conversion of 7 to bismesylate 8 proceeded smoothly in 92% yield under standard conditions. The symmetry-breaking step in this route involved treatment of 8 with one equivalent of sodium azide in

• changing the order of these steps would be beneficial. Alkylation of terephthalate 12 with azido-bromide 6 using cesium carbonate as the base provided high yields (82%) of core diazide 14 (Scheme 3). Click cycloaddition of 14 with an excess of dialkyne 10 also proceeded in high yields (87%) to give diester

Chan–Evans–Lam N1-(het)arylation and N1-alkеnylation of 4-fluoroalkylpyrimidin-2(1H)-ones

• Viktor M. Tkachuk,
• Oleh O. Lukianov,
• Mykhailo V. Vovk,
• Isabelle Gillaizeau and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2020, 16, 2304–2313, doi:10.3762/bjoc.16.191

• . Average product yields of 38–69% were observed for the reaction run in methanol, dichloroethane, tetrahydrofuran, and ethyl acetate (Table 1, entries 13–15, 20 and 21). In dimethyl carbonate and DMSO solutions, the yields were reduced to 4 and 11%, respectively (Table 1, entries 22 and 23). In contrast

Azo-dimethylaminopyridine-functionalized Ni(II)-porphyrin as a photoswitchable nucleophilic catalyst

• Jannis Ludwig,
• Julian Helberg,
• Hendrik Zipse and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2119–2126, doi:10.3762/bjoc.16.179

• -epoxypropane to propylene carbonate using an aluminum porphyrin and a photoresponsive ligand. The catalytic activity of the metal porphyrin depended on the axial coordination of an azostilbene and coordination of the latter ligand was controlled by photoisomerization of the stilbene unit [9]. Hecht et al

Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2H-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction

• Alexander N. Reznikov,
• Dmitry S. Nikerov,
• Anastasiya E. Sibiryakova,
• Victor B. Rybakov,
• Evgeniy V. Golovin and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2020, 16, 2073–2079, doi:10.3762/bjoc.16.174

• detected in the reaction even after 72 h in the presence of 1 equiv of potassium phosphate or carbonate with TEBAC (0.1 equiv, Table 1, entries 4 and 5). If potassium fluoride or cesium carbonate were used as a base, the initial phosphonate 6e was consumed in a few hours, but unidentified products were

Design, synthesis and application of carbazole macrocycles in anion sensors

• Alo Rüütel,
• Ville Yrjänä,
• Sandip A. Kadam,
• Indrek Saar,
• Mihkel Ilisson,
• Astrid Darnell,
• Kristjan Haav,
• Tõiv Haljasorg,
• Lauri Toom,
• Johan Bobacka and
• Ivo Leito

Beilstein J. Org. Chem. 2020, 16, 1901–1914, doi:10.3762/bjoc.16.157

• interference from chloride. Chloride was at least partially responsible for the deviations observed above pH 8 and pH 9, but interference from hydroxide and/or carbonate cannot be ruled out. The selectivity of each membrane was evaluated with the separate solution method. The results for each interfering ion

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

• , the limited substrate scope, and complicated work-up processes; further, the products require chromatographic purification. The mineral NDL is an irregular combination of calcium and magnesium carbonate. It is water-insoluble, environmentally benevolent, inexpensive, nontoxic, and abundant in nature

• , Andhra Pradesh, India. The rock formation in the mineralized area of this village belongs to the Vempalli Formation (VF) of the Papaghni group of the lower Cuddapah Supergroup in the Cuddapah Basin (CB). The carbonate minerals, such as limestone and dolomite, are the most abundant ones and common

• asymmetric stretching vibration (ν3) of the carbonate group, respectively. The combined bands of the carbonate group, i.e., ν1 + ν4 and ν1 + ν3 were observed at 1798 and 2524 cm−1, respectively [76][77][81]. The IR bands at 3446 cm−1 (broad) and 1674 cm−1 (sharp) indicated the presence of stretching and

On the hydrolysis of diethyl 2-(perfluorophenyl)malonate

• Ilya V. Taydakov and
• Mikhail A. Kiskin

Beilstein J. Org. Chem. 2020, 16, 1863–1868, doi:10.3762/bjoc.16.153

• readily accessible compound. Diethyl 2-phenylmalonate (4) is usually obtained (Scheme 1) by condensation of ethyl phenylacetate (5) and diethyl carbonate under basic conditions [22] because of the low reactivity of bromobenzene in noncatalytic nucleophilic reactions with sodium salts of diethyl malonate

One-pot synthesis of oxazolidinones and five-membered cyclic carbonates from epoxides and chlorosulfonyl isocyanate: theoretical evidence for an asynchronous concerted pathway

• Esra Demir,
• Ozlem Sari,
• Yasin Çetinkaya,
• Ufuk Atmaca,
• Safiye Sağ Erdem and
• Murat Çelik

Beilstein J. Org. Chem. 2020, 16, 1805–1819, doi:10.3762/bjoc.16.148

• toloxatone derivatives, have been reported to exhibit good affinity for human MAO-A [14]. Five-membered cyclic carbonate (1,3-dioxolan-2-one) (2) and its derivatives are valuable synthetic targets on account of several applications and pertinent properties. They are found in various natural and potential

• polymerization of the compounds containing cyclic carbonates such as methyl 4,6-O-benzylidene-2,3-O-carbonyl-α-ᴅ-glucopyranoside (MBCG) (5) [19][20] and glycerol carbonate (6) [21] were also reported (Scheme 1). Therefore, numerous synthetic approaches have been developed to date for the preparation of

• natural products ranging from small molecules, such as sugars, lipids and amino acids to huge molecules [56]. Computational results A detailed mechanistic investigation of the synthesis of oxazolidinone and five-membered cyclic carbonate derivatives by the reaction between epoxide 7f and CSI has been

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

• diluted with toluene (60 mL) and then washed with a saturated sodium hydrogen carbonate solution (30 mL) and brine (30 mL). The organic layer was dried over MgSO4, and the volatile components were removed under reduced pressure. The resulting residue was dissolved in methanol and purified by PLC (using

• additional 15 min. The reaction mixture was poured into a separating funnel containing DCM (15 mL) and a saturated sodium hydrogen carbonate solution (15 mL). The organic layer was further washed with brine (15 mL) and then dried with MgSO4. The volatile components were removed under reduced pressure, the

• solution was stirred for an additional 15 min. The reaction mixture was diluted with toluene (15 mL) and poured into a separating funnel containing a saturated sodium hydrogen carbonate solution (10 mL). The organic phase was washed with brine, dried with MgSO4, and the volatile components were removed

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

• cyclohexene, maleic anhydride, ethylene carbonate, and 1-octene, the desired products were not formed under the reaction conditions. In the same year, Helaja and co-workers examined the electronic effects of the alkyne substituent on the regioselectivity of the microwave-assisted PKR with norbornene [80]. The

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

• performed in order to prove that the transition states connect two corresponding minima. General procedure I for the synthesis of compounds 2a,b, 3a,b, 8a,b, and 23a. TFA (0.1 equiv) was added to a solution of 1a–e in DCM (20 mL). After stirring for 24 h at room temperature, an aqueous sodium carbonate

• , and recrystallized from EtOAc/hexane to afford the title compounds as white solids. General procedure II for the synthesis of compounds 2a,b, 3a,b, 8a,b and 23a. TFA (0.1 equiv) was added to a solution of 1a–e in THF (20 mL). After stirring for 24 h at room temperature, an aqueous sodium carbonate

NHC-catalyzed enantioselective synthesis of β-trifluoromethyl-β-hydroxyamides

• Alyn T. Davies,
• Mark D. Greenhalgh,
• Alexandra M. Z. Slawin and
• Andrew D. Smith

Beilstein J. Org. Chem. 2020, 16, 1572–1578, doi:10.3762/bjoc.16.129

• observed, which served as a basis for further optimization. Variation of the base showed caesium carbonate to be significantly more effective than the organic bases examined, giving 88% conversion to product 6 (Table 1, entries 2 and 3). Trialling a number of alternative solvents, including dichloromethane

Mechanochemical green synthesis of hyper-crosslinked cyclodextrin polymers

• Alberto Rubin Pedrazzo,
• Fabrizio Caldera,
• Marco Zanetti,
• Silvia Lucia Appleton,
• Nilesh Kumar Dhakar and
• Francesco Trotta

Beilstein J. Org. Chem. 2020, 16, 1554–1563, doi:10.3762/bjoc.16.127

• crosslinker. The polymer obtained exhibited the same characteristics as a CD-based carbonate NS synthesized in a solvent. Moreover, after the synthesis, the polymer was easily functionalized through the reaction of the nucleophilic carboxylic group with three different organic dyes (fluorescein, methyl red

• degree of crosslinking, thus influencing the final properties [1][2]. Among the various bifunctional compounds that could be used as crosslinking agents, active carbonyl compounds, such as carbonyldiimidazole (CDI) and diphenyl carbonate have given interesting results in the last 20 years. The produced

• CD nanosponges, after crosslinking, comprise carbonate bonds between the cyclodextrin monomers. If this reaction is carried out under classical conditions in a N,N-dimethylformamide (DMF) solution, an amorphous crosslinked insoluble polymer is obtained. In general, carbonate nanosponges are insoluble

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

The McKenna reaction – avoiding side reactions in phosphonate deprotection

• Katarzyna Justyna,
• Joanna Małolepsza,
• Damian Kusy,
• Waldemar Maniukiewicz and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119

• from the reaction mixture by washing with aqueous sodium carbonate solution. The model compounds used for this study (in red: the functionality of the molecules vulnerable to side reactions). Schematic overview of the McKenna reaction including the decomposition of BTMS in protic solvents. The desired

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• the surface of the treated carbons in form of carboxyl groups, ketones, ether groups and carboxyl-carbonate structures is higher using nitric acid compared to hydrogen peroxide [116]. Nitrogen adsorption–desorption isotherms: The surface area and pore size distribution of solid catalyst materials can

• carbonates. Moreover, they found that no porosity of the resulting materials was formed by using a metal carbonate instead of hydroxide as activation reagent [8][14]. Pis and co-workers used the TPD method for evaluation of the thermal stability of introduced nitrogen functionalities by modification with

Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties

• Nuray Altinolcek,
• Ahmet Battal,
• Mustafa Tavasli,
• William J. Peveler,
• Holly A. Yu and
• Peter J. Skabara

Beilstein J. Org. Chem. 2020, 16, 1066–1074, doi:10.3762/bjoc.16.93

• either with 2-bromopyridine-4-carbaldehyde (6a) or 2-bromopyridine-5-carbaldehyde (6b) in the presence of potassium carbonate and bis(triphenylphosphine)palladium(II) dichloride in tetrahydrofuran [2]. Upon repeated purification by chromatography, compounds 7a and 7b were obtained as liquids in good

• pinacol ester (5, 447 mg, 1.2 mmol), 2-bromopyridine-4-carbaldehyde (6a, 147 mg, 0.8 mmol), potassium carbonate (1 M, 9.6 mL) and dichlorobis(triphenylphosphine)palladium(II) (40 mg, 0.06 mmol) were dissolved in tetrahydrofuran (20 mL). The reaction mixture was refluxed for 24 h under an argon atmosphere

• , 2911, 2872, 2851, 1697; anal. calcd for C24H24N2O, C: 80.87, H: 6.79, N: 7.86; found: C: 80.86, H: 6.92, N: 7.57. Compound 7b: (9-Hexylcarbazol-3-yl)boronic acid pinacol ester (5, 144 mg, 0.4 mmol), 2-bromopyridine-5-carbaldehyde (6b, 47 mg, 0.3 mmol), potassium carbonate (1 M, 3 mL) and dichlorobis

Suzuki–Miyaura cross coupling is not an informative reaction to demonstrate the performance of new solvents

• James Sherwood

Beilstein J. Org. Chem. 2020, 16, 1001–1005, doi:10.3762/bjoc.16.89

• conventional solvents. In this work, the suitability of the Suzuki–Miyaura reaction to demonstrate the usefulness of new solvents was evaluated, including Cyrene™, dimethyl isosorbide, ethyl lactate, 2-methyltetrahydrofuran (2-MeTHF), propylene carbonate, and γ-valerolactone (GVL). It was found that the cross

• lactate [10], 2-methyltetrahydrofuran (2-MeTHF) [11], γ-valerolactone (GVL) [12], dimethyl isosorbide (DMI) [6], and propylene carbonate [7]. This study compares solvents under the same conditions to offer a fair comparison. Additional solvents were included to ensure a range of polarities were

•  1b) [13]. Here, palladium acetate without an auxiliary ligand was used for a pre-catalyst and the base changed to potassium carbonate. Reaction conditions of 20 hours at 65 °C were decided after observing 11% conversion after 2 hours and 33% after 20 hours in NMP at room temperature. The majority of

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• photoinduced cycloaddition of carbon dioxide with epoxides [56]. The synthesis of a 3D supramolecular framework, [{Mn(TCPP)0.5(H2O)}·2H2O]n, where Mn(TCPP) is Mn(II) meso-tetrakis(4-carboxyphenyl)porphyrin, was derived from MnCl2·6H2O and TCPP. The cycloaddition product, a cyclic carbonate, was obtained from

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

• Liliia Moshniaha,
• Marika Żyła-Karwowska,
• Joanna Cybińska,
• Piotr J. Chmielewski,
• Ludovic Favereau and
• Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

• (NDA) and naphthalenemonoimide (NMI) moieties. The double C–H bond activation initially used palladium(II) acetate in acetic acid as the coupling system. The subsequent screening revealed, however, that a catalytic coupling could be also achieved in the presence of silver(I) carbonate as the

• that the coupling and α-oxygenation can also be achieved with 1 equiv of Pd(OAc)2 in the presence of 2 equiv of silver carbonate. Nevertheless, Ag2CO3 oxidation provided lower yields and the efficiency of this variant was dramatically diminished when the loading of palladium(II) acetate was decreased

Photocatalytic deaminative benzylation and alkylation of tetrahydroisoquinolines with N-alkylpyrydinium salts

• David Schönbauer,
• Carlo Sambiagio,
• Timothy Noël and
• Michael Schnürch

Beilstein J. Org. Chem. 2020, 16, 809–817, doi:10.3762/bjoc.16.74

• ). Eosin Y was inefficient under these conditions (Table 1, entry 20). Since [Ru(bpy)3]Cl2 is significantly cheaper than the iridium catalyst, the former was used in further reactions. Regarding the addition of different bases, the yield remained unchanged, when lutidine was added. Potassium carbonate and

Reaction of indoles with aromatic fluoromethyl ketones: an efficient synthesis of trifluoromethyl(indolyl)phenylmethanols using K₂CO₃/n-Bu₄PBr in water

• Thanigaimalai Pillaiyar,
• Masoud Sedaghati and
• Gregor Schnakenburg

Beilstein J. Org. Chem. 2020, 16, 778–790, doi:10.3762/bjoc.16.71

• (TMG), also known as Barton's base, in excellent yields (Figure 2A) [24]. Recently, Liu and co-workers reported this reaction in the presence of cesium carbonate in acetonitrile (Figure 2B) [25]. Dinuclear zinc [26], cinchonidine catalysts, and solvent-free conditions [27] have been also utilized for

• of potassium carbonate and tetrabutylphophonium bromide, which mediate the reaction in water through the formation of the interface between organic and aqueous phases. The advantageous of this reaction include high yields, no column chromatography, broad substrate scope, multiscale synthesis, and

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• ]. 2.1 Formation and reactions of allylic C–B bonds The synthesis of α-stereogenic allylboronates was reported by Ito in 2005 using CuO-t-Bu/Xantphos (CuCl and KO-t-Bu form CuO-t-Bu in situ as the active catalyst precursor), an enantioenriched allyl carbonate, and B2pin2 (310; Scheme 50) [93]. Both (Z

• ] with C(sp2)-containing electrophiles such as tert-butyl allyl carbonate or aldimines using B2pin2, Liao et al. reported the same approach, albeit using more challenging C(sp3) electrophiles (e.g., CH3I) for the enantioselective methylboration. Both aliphatic alkenes and styrenes could be used with

Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment

• Jan Geldsetzer and
• Markus Kalesse

Beilstein J. Org. Chem. 2020, 16, 670–673, doi:10.3762/bjoc.16.64

• choice in this type of coupling reaction. Potassium carbonate was chosen due to the sensitivity of the amide 3 towards harsh basic conditions. With these conditions we were able to couple (Z)-bromide 4 with amide 3 selectively to yield (Z)-enamide 16. The obtained double bond geometry was confirmed by

• the indicative NMR coupling constants of 9.6 Hz. Moreover, we observed a concentration dependent formation of the undesired desilylated (Z)-enamide 17 (Table 1). The best results were achieved using a 65 mM solution of the amide 3. Using dry potassium carbonate, purified copper(I) iodide provided the

KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

• Qiao Lin,
• Shiling Zhang and
• Bin Li

Beilstein J. Org. Chem. 2020, 16, 492–501, doi:10.3762/bjoc.16.44

• solvents, including toluene, EtOH, THF, H2O, CH2Cl2 and dimethyl carbonate (DMC). Among them, DMC afforded the product 3a in an excellent yield and as greener solvent compared to CH3CN, it was selected as the best solvent for this ring-opening N-alkylation (Table 1, entry 11). When replacing KOt-Bu by