Synthesis and SAR of the antistaphylococcal natural product nematophin from Xenorhabdus nematophila

• Frank Wesche,
• Hélène Adihou,
• Thomas A. Wichelhaus and
• Helge B. Bode

Beilstein J. Org. Chem. 2019, 15, 535–541, doi:10.3762/bjoc.15.47

• bond formation was achieved using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl), 1-hydroxybenzotriazole (HOBt) and N,N-diisopropylethylamine (DIPEA) in DMF under microwave irradiation (Scheme 1). Racemic 1 was synthesized using tryptamine and (rac)-3-methyl-2-oxopentanoic acid

• phthalimides 16 and 23 [29]. These intermediary compounds 16 and 23 also allowed an N-methylation of the azaindole moiety with sodium hydride (NaH) and methyl iodide (MeI) to yield 17 and 24. By ethanolic hydrazinolysis and microwave irradiation the phthalimides (16, 17, 23, and 24) were deprotected yielding

Design of indole- and MCR-based macrocycles as p53-MDM2 antagonists

• Constantinos G. Neochoritis,
• Maryam Kazemi Miraki,
• Eman M. M. Abdelraheem,
• Ewa Surmiak,
• Tryfon Zarganes-Tzitzikas,
• Beata Łabuzek,
• Tad A. Holak and
• Alexander Dömling

Beilstein J. Org. Chem. 2019, 15, 513–520, doi:10.3762/bjoc.15.45

• optimization, we improved the Ugi-macrocyclization procedure compared to our previous findings utilizing microwave irradiation (see Supporting Information File 1); Firstly, the corresponding amino acid was irradiated with indole-3-carboxaldehyde derivatives 6 using MeOH as solvent (5 mL) at 120 °C for 1 h

Microwave-assisted synthesis of N,N-bis(phosphinoylmethyl)amines and N,N,N-tris(phosphinoylmethyl)amines bearing different substituents on the phosphorus atoms

• Erika Bálint,
• Anna Tripolszky,
• László Hegedűs and
• György Keglevich

Beilstein J. Org. Chem. 2019, 15, 469–473, doi:10.3762/bjoc.15.40

• phosphorus atoms was synthesized by the microwave-assisted and catalyst-free Kabachnik–Fields reaction of (aminomethyl)phosphine oxides with paraformaldehyde and diphenylphosphine oxide. The three-component condensation of N,N-bis(phosphinoylmethyl)amine, paraformaldehyde and a secondary phosphine oxide

• affording N,N,N-tris(phosphinoylmethyl)amine derivatives was also elaborated. This method is a novel approach for the synthesis of the target products. Keywords: (aminomethyl)phosphine oxides; Kabachnik–Fields reaction; ligand; microwave; N,N-bis(phosphinoylmethyl)amines; N,N,N-tris(phosphinoylmethyl

• well as by the reaction of (hydroxymethyl)dibenzylphosphine oxide and aniline [8]. The condensation of butylamine, paraformaldehyde and di(p-tolyl)phosphine oxide to afford (butylaminomethyl)di(p-tolyl)phosphine oxide was also described [9]. A microwave (MW)-assisted, catalyst-free method was

Ammonium-tagged ruthenium-based catalysts for olefin metathesis in aqueous media under ultrasound and microwave irradiation

• Łukasz Gułajski,
• Andrzej Tracz,
• Katarzyna Urbaniak,
• Stefan J. Czarnocki,
• Michał Bieniek and
• Tomasz K. Olszewski

Beilstein J. Org. Chem. 2019, 15, 160–166, doi:10.3762/bjoc.15.16

• Abstract The influence of microwave and ultrasonic irradiation on the performance of ammonium-tagged Ru-based catalysts in olefin metathesis transformations in aqueous media was studied. Differences in the catalytic activity in correlation with the nature of the present counter ion and the size of the N

• -heterocyclic carbene (NHC) ligand were revealed. The presented methodology allows for preparation of a variety of polar and non-polar metathesis products under environmentally friendly conditions. Keywords: catalysis; green chemistry; microwave; N-heterocyclic carbene; olefin metathesis; ruthenium; ultrasound

• interesting transformation. Furthermore, in the continuous search for new sustainable protocols for chemical reactions to induce new reactivates or reduce the energetic cost of the processes, the replacement of mechanical mixing and/or heating of the reacting species with microwave (μW) [46][47][48] and

Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins

• Christiane Schultze and
• Bernd Schmidt

Beilstein J. Org. Chem. 2018, 14, 2991–2998, doi:10.3762/bjoc.14.278

• Christiane Schultze Bernd Schmidt Universität Potsdam, Institut fuer Chemie, Karl-Liebknecht-Straße 24–25, D-14476 Potsdam-Golm, Germany 10.3762/bjoc.14.278 Abstract 8-Allylcoumarins are conveniently accessible through a microwave-promoted tandem Claisen rearrangement/Wittig olefination

• application of sequential one-pot transformations and motivated by the relevance of prenylated and other substituted coumarins in natural products and medicinal chemistry, we [27][28][29] and others [30] have investigated a microwave-promoted tandem reaction for the synthesis of 8-substituted coumarins over

• the past few years. Starting materials are allyl ethers of salicylic aldehydes or ketones 5 and the stable ylide ethyl (triphosphoranylidene)acetate (6), which upon microwave irradiation undergo a tandem Claisen rearrangement/Wittig olefination/cyclization sequence. This sequence was pioneered by the

MoO₃ on zeolites MCM-22, MCM-56 and 2D-MFI as catalysts for 1-octene metathesis

• Hynek Balcar,
• Martin Kubů,
• Naděžda Žilková and
• Mariya Shamzhy

Beilstein J. Org. Chem. 2018, 14, 2931–2939, doi:10.3762/bjoc.14.272

• OES (iCAP 7000, Thermo Scientific) was used. About 50 mg of the catalyst was digested in a mixture of HF, HCl, and HNO3 (1:2:2). The samples were placed in a Berghof microwave in a closed vessel at T = 140 °C for 35 min. Saturated solution of H3BO3 was then added for complexation of the excess of HF

Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions

• Glwadys Gagnot,
• Vincent Hervin,
• Eloi P. Coutant,
• Sarah Desmons,
• Racha Baatallah,
• Victor Monnot and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2846–2852, doi:10.3762/bjoc.14.263

• undertook this reaction under argon in ethanol at 110 °C using a microwave reactor along with only one equivalent of DBU and these changes provided us with the ethyl ester 42 in a 51% yield. Finally, a far more simple procedure was found by just adding a catalytic amount of hydrogen chloride in 1,4-dioxane

Pd-Catalyzed microwave-assisted synthesis of phosphonated 13α-estrones as potential OATP2B1, 17β-HSD1 and/or STS inhibitors

• Rebeka Jójárt,
• Szabolcs Pécsy,
• György Keglevich,
• Mihály Szécsi,
• Réka Rigó,
• Csilla Özvegy-Laczka,
• Gábor Kecskeméti and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 2838–2845, doi:10.3762/bjoc.14.262

• reacted with diethyl phosphite or diphenylphosphine oxide using Pd(PPh3)4 as catalyst under microwave irradiation. The influence of the new compounds on the transport function of the organic anion transporting polypeptide OATP2B1 was investigated by measuring Cascade Blue uptake. Derivatives bearing a 3

• . Here we disclose the synthesis of novel 2- or 4-substituted 13α-estrone derivatives 8–13 via the Hirao reaction (Scheme 1). Diethyl phosphite (7a) or diphenylphosphine oxide (7b) were chosen as >P(O)H reagents and C–P couplings were planned under microwave irradiation using Pd-based catalysis

• , but the important benefits of microwave-irradiation have also been utilized in this field [29]. The optimization of reaction conditions was carried out using 2-bromo- or 2-iodo-13α-estrone 3-methyl ether (1 or 1I) as starting compounds and diethyl phosphite (7a) as the reagent (Table 1, Scheme 1). Two

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• -methyl-1H-imidazolium chloride (66) ILs were used as excellent catalysts and the reaction medium for microwave synthesis of quinoline derivatives 65 from substituted anilines 15 and glycerol (64, Scheme 11). Some advantages of these catalytic systems include: elimination of oxidizing agents, ease of

• polyhydroquinoline derivatives 118 under microwave irradiation. Several substituted aldehydes 7 with dimedone (20), acetoacetate ester 34a, and ammonium acetate in ethanol under microwave irradiation were reacted to produce corresponding products in high yields. In addition to the catalytic role of strong acid

• -xylose (139) into furfural (140) was performed in water-CPME (1:3, v/v) and heated in a commercial monowave microwave oven in the presence of 10 wt % of 138 for 50 min. A maximum furfural yield of 76% was obtained. A new sulfonated graphene catalyst GR-SO3H (145) was prepared in some steps. A mixture of

Microwave-assisted synthesis of biologically relevant steroidal 17-exo-pyrazol-5'-ones from a norpregnene precursor by a side-chain elongation/heterocyclization sequence

• Gergő Mótyán,
• László Mérai,
• Márton Attila Kiss,
• Zsuzsanna Schelz,
• Izabella Sinka,
• István Zupkó and
• Éva Frank

Beilstein J. Org. Chem. 2018, 14, 2589–2596, doi:10.3762/bjoc.14.236

• -activated acylimidazole derivative was then converted to a β-ketoester containing a two carbon atom-elongated side chain than that of the starting material. A Knorr cyclization of the bifunctional 1,3-dicarbonyl compound with hydrazine and its monosubstituted derivatives in AcOH under microwave heating

• the reference compound, cisplatin. Keywords: antiproliferative activity; Knorr reaction; microwave; pyrazol-5-ones; steroids; Introduction 17-exo-Heterocyclic androstanes with five or six-membered heterocyclic rings connected directly to C-17 of the sterane core represent a remarkable subclass of

• as the necessity of high temperature or prolonged reaction time and low yields of the desired products [14]. A rate acceleration and yield improvement could be achieved in some cases by performing the reactions under microwave (MW) conditions [15][16][17]. Especially with respect to pyrazol-5-ones

Gold-catalyzed post-Ugi alkyne hydroarylation for the synthesis of 2-quinolones

• Xiaochen Du,
• Jianjun Huang,
• Anton A. Nechaev,
• Ruwei Yao,
• Jing Gong,
• Erik V. Van der Eycken,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2018, 14, 2572–2579, doi:10.3762/bjoc.14.234

• Xiaochen Du Jianjun Huang Anton A. Nechaev Ruwei Yao Jing Gong Erik V. Van der Eycken Olga P. Pereshivko Vsevolod A. Peshkov College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Dushu Lake Campus, Suzhou, 215123, China Laboratory for Organic & Microwave-Assisted

Synthesis of dihydroquinazolines from 2-aminobenzylamine: N³-aryl derivatives with electron-withdrawing groups

• Nadia Gruber,
• Jimena E. Díaz and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2018, 14, 2510–2519, doi:10.3762/bjoc.14.227

• -aryl-2-iminoazacycloalkanes [84] and 2-oxazolines or their higher homologues [85], using polyphosphoric acid esters PPE (ethyl polyphosphate) [86] and PPSE (trimethylsilyl polyphosphate) [87] under microwave irradiation. PPE and PPSE are aprotic irreversible dehydrating agents of the Lewis acid-type

• esters are their low cost, operational simplicity and minimum environmental impact. Besides, their use together with microwave irradiation brings about shorter reaction times, cleaner crude products and consequently higher yields. On the basis of our previous work on DHQs [41], we explore herein the use

• ’-diacylation products were observed due to the low nucleophilicity of the secondary amino group, bearing a deactivating aromatic ring and all desired compounds were obtained with excellent yields (Table 2). Then, the microwave-assisted cyclization reaction leading to 3,4-dihydroquinazolines 1 was initially

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• , Claisen rearrangement (CR) of 77 under microwave irradiation (MWI) conditions on a silica gel support followed by O-allylation of the resulting CR product furnished diallyl compound 78. Treatment of diallyl compound 78 with G-I catalyst 1 delivered the expected naphthoxepine derivative 79 (96%). Next

• -Doctoral Fellow at the KU Leuven, Belgium under the EMINTE programme. During post-doctoral work his research work was related to organic synthesis under microwave reaction conditions. Presently, he is Research Associate with Prof. S. Kotha. His research interests include various transition-metal-catalyzed

Catalyst-free synthesis of 4-acyl-NH-1,2,3-triazoles by water-mediated cycloaddition reactions of enaminones and tosyl azide

• Lu Yang,
• Yuwei Wu,
• Yiming Yang,
• Chengping Wen and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2018, 14, 2348–2353, doi:10.3762/bjoc.14.210

• synthesis of N-substituted 1,2,3-triazoles via the reactions of organoazides and the in situ prepared N,N-dimethylenaminones by 150 °C microwave irradiation and subsequent heating in toluene at 100 °C, providing an effective protocol of enaminone-based 1,2,3-triazole synthesis. Interestingly, our continuous

Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates

• Vladimir A. Burilov,
• Guzaliya A. Fatikhova,
• Mariya N. Dokuchaeva,
• Ramil I. Nugmanov,
• Diana A. Mironova,
• Pavel V. Dorovatovskii,
• Victor N. Khrustalev,
• Svetlana E. Solovieva and
• Igor S. Antipin

Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173

• complete O-alkylation of the parent p-tert-butylcalix[4]arene was performed to give the products 5a,b. To achieve the selective distal alkylation of the macrocycle’s lower rim (compounds 1a,b) a microwave approach developed in our group was applied [32]. Then the di- and tetraalkylated products were

Cationic cobalt-catalyzed [1,3]-rearrangement of N-alkoxycarbonyloxyanilines

• Itaru Nakamura,
• Mao Owada,
• Takeru Jo and
• Masahiro Terada

Beilstein J. Org. Chem. 2018, 14, 1972–1979, doi:10.3762/bjoc.14.172

• and alkoxylcarbonyloxy groups generally require long heating times at elevated reaction temperatures (>140 °C) or microwave irradiation (Scheme 2a). In contrast, N-sulfonyloxyanilines are known to readily undergo the [3,3]-rearrangement during the preparation of the starting material below −20 °C due

Assessing the possibilities of designing a unified multistep continuous flow synthesis platform

• Mrityunjay K. Sharma,
• Roopashri B. Acharya,
• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2018, 14, 1917–1936, doi:10.3762/bjoc.14.166

• permeable membrane reactors [46][47][48], high-pressure reactors utilizing back pressure regulators [49][50][51], reactors with different heating and cooling modes (e.g., inductive heating [11][52], microwave [53][54][55] etc.) and many more, also very special reactors [56] with other difficulties that need

Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium

• Alphonse Fiebor,
• Richard Tia,
• Banothile C. E. Makhubela and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160

• microwave heating [7][8][9][10][11][12][13][14][15], ultrasonication [16][17][18], ligand-free methodologies [19][20][21][22][23][24][25] and the use of water-soluble palladium pre-catalysts/catalysts [26][27][28][29][30]. The latter is the preferred choice since it allows for the reusability of the

Defining the hydrophobic interactions that drive competence stimulating peptide (CSP)-ComD binding in Streptococcus pneumoniae

• Bimal Koirala,
• Robert A. Hillman,
• Erin K. Tiwold,
• Michael A. Bertucci and
• Yftah Tal-Gan

Beilstein J. Org. Chem. 2018, 14, 1769–1777, doi:10.3762/bjoc.14.151

• ) procedures [34]. Phenylglycine and norvaline derivatives were prepared on a CEM Discover microwave synthesizer, with diisopropyl carbodiimide (DIC) as the coupling reagent along with Oxyma Pure. The ratio of DIC:Oxyma Pure:AA was 3.6:3:3 dissolved in N,N-dimethylformamide (DMF) for a final DIC concentration

Synthesis and photophysical studies of a multivalent photoreactive Ru^II-calix[4]arene complex bearing RGD-containing cyclopentapeptides

• Sofia Kajouj,
• Lionel Marcelis,
• Alice Mattiuzzi,
• Adrien Grassin,
• Damien Dufour,
• Pierre Van Antwerpen,
• Didier Boturyn,
• Eric Defrancq,
• Mathieu Surin,
• Julien De Winter,
• Pascal Gerbaux,
• Ivan Jabin and
• Cécile Moucheron

Beilstein J. Org. Chem. 2018, 14, 1758–1768, doi:10.3762/bjoc.14.150

• reported in the field of calixarene chemistry [66][73][74][75][76][77][78]. Unfortunately, this methodology led to poor yields and a lack of reproducibility in the case of calixarene 7 and c-[RGDfK]-alkyne 8, even when a microwave heating was used. We then evaluated the use of copper nanoparticles (CuNPs

• ), as these nanomaterials are known to catalyze efficiently a wide range of organic reactions and notably the azide–alkyne cycloaddition [79]. Calixarene 7 was reacted with a slight excess (5 equiv) of cyclopeptide 8 in the presence of CuNPs and the mixture was heated by microwave (100 W) at 50 °C for 1

Synthesis of pyrimido[1,6-a]quinoxalines via intermolecular trapping of thermally generated acyl(quinoxalin-2-yl)ketenes by Schiff bases

• Svetlana O. Kasatkina,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev,
• Ivan G. Mokrushin and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2018, 14, 1734–1742, doi:10.3762/bjoc.14.147

• quinoxalin-2-ylideneacetates [9], multicomponent Mannich–Ritter transformations of quinoxalin-2(1H)-ones under the action of nitriles and 3,4-dihydro-2H-pyran [10] and a microwave-assisted cascade strategy via in situ-generated N-acyliminium ion precursors and amines [11] (Figure 2). To develop a new

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• go to completion. The crude isolated products exhibited very low solubility in solvents usually recommended for standard N-acylations (acetone, THF, 1,4-dioxane, pyridine, etc.). Treatment of these acid chlorides with G-1 dendron D-N

  NH (3 equiv) under various conditions (microwave-assisted organic

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• catalyst loading required as well as recoverability and reusability without any significant loss of activity in terms of reaction time, selectivity and yield. For reactions that are sluggish and mostly require heating, microwave irradiation is reported to significantly improve reaction rates, selectivities

• electron rich ones such as p-methylthiophenol, giving the corresponding products in very high yields. Unlike in the microwave irradiation protocol, the reaction of aliphatic thiols with epoxides proceeded smoothly to give excellent yields. In another contribution, Su et al. carried out thiolysis of

• oxidation to β-hydroxy sulfoxides under microwave irradiation. Gallium triflate-catalyzed ring opening of epoxides and one-pot oxidation. Thiolysis of epoxides and one-pot oxidation to β-hydroxy sulfoxides using Ga(OTf)3 as a catalyst. Ring opening of epoxide using ionic liquids under solvent-free

The phenyl vinyl ether–methanol complex: a model system for quantum chemistry benchmarking

• Dominic Bernhard,
• Fabian Dietrich,
• Mariyam Fatima,
• Cristóbal Pérez,
• Hannes C. Gottschalk,
• Axel Wuttke,
• Ricardo A. Mata,
• Martin A. Suhm,
• Melanie Schnell and
• Markus Gerhards

Beilstein J. Org. Chem. 2018, 14, 1642–1654, doi:10.3762/bjoc.14.140

• -docking motifs via the phenyl and vinyl moieties, with an additional less populated OH∙∙∙P(phenyl)-bound isomer detected only by microwave spectroscopy. The correct prediction of the energetic order of the isomers using quantum-chemical calculations turns out to be challenging and succeeds with a

• Fourier transform microwave (CP-FTMW) spectroscopy. Comparing spectroscopic results with quantum-chemical calculations is often mandatory for the interpretation of experiments. Furthermore, such comparison enables a critical evaluation of the approximations used, comparing the relative stability of

• different binding motifs. In this paper, the first structural investigation on the complex of phenyl vinyl ether with methanol is presented. An established multi-spectroscopic approach [19][20] is used, coupling FTIR, IR/UV and microwave spectroscopy with theoretical treatments including dispersion

Synthesis of pyrazolopyrimidinones using a “one-pot” approach under microwave irradiation

• Mark Kelada,
• John M. D. Walsh,
• Robert W. Devine,
• Patrick McArdle and
• John C. Stephens

Beilstein J. Org. Chem. 2018, 14, 1222–1228, doi:10.3762/bjoc.14.104

• the microwave-assisted synthesis of substituted pyrazolo[1,5-a]pyrimidinones, a core scaffold in many bioactive and pharmaceutically relevant compounds, has been established. A variety of substituents was tolerated at the 2 and 5 positions, including functionalized aryls, heterocycles, and alkyl

• groups. Keywords: microwave-assisted synthesis; nitrogen-fused heterocycle; one-pot; pyrimidinone; Introduction The pyrazolo[1,5-a]pyrimidinone is a fused nitrogen-containing heterocyclic system and is of interest due to its role as a basic core scaffold in many bioactive and pharmaceutically relevant

• . Herein, we report such a strategy for the simple synthesis of functionalized pyrazolo[1,5-a]pyrimidinones that employs a one-pot microwave-assisted approach. Findings A number of synthetic approaches have been developed for the synthesis of privileged nitrogen-fused bicyclic systems such as the pyrazolo