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Search for "microwave irradiation" in Full Text gives 234 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

  • Carolina S. García,
  • Paula M. Uberman and
  • Sandra E. Martín

Beilstein J. Org. Chem. 2017, 13, 1717–1727, doi:10.3762/bjoc.13.166

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  • Mizoroki–Heck coupling reactions under microwave irradiation (MW) were carried out with a colloidal Pd nanocatalyst stabilized with poly(N-vinylpyrrolidone) (PVP). Many stilbenes and novel heterostilbenes were achieved in good to excellent yields starting from aryl bromides and different olefins. The
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Published 18 Aug 2017

Synthesis and metal binding properties of N-alkylcarboxyspiropyrans

  • Alexis Perry and
  • Christina J. Kousseff

Beilstein J. Org. Chem. 2017, 13, 1542–1550, doi:10.3762/bjoc.13.154

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  • , robust conditions. Reported protocols have employed chloroform [3], acetonitrile [19], acetone [20], nitromethane [21], 1,2-dichlorobenzene [22], toluene [23], reaction in the absence of solvent [24] or use of microwave irradiation [25]. We found that refluxing acetonitrile was relatively effective, if
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Published 04 Aug 2017

Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid

  • Kohei Yamada,
  • Naoto Kamimura and
  • Munetaka Kunishima

Beilstein J. Org. Chem. 2017, 13, 1478–1485, doi:10.3762/bjoc.13.146

Graphical Abstract
  • temperature to 80 °C or increasing to 160 °C by microwave irradiation were not effective for improving the reaction (Table 2, entries 16 and 17). Consequently, we found that the reaction shown in entry 4 afforded the optimal result (see Table S1 in Supporting Information File 1 for further manipulation of the
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Published 27 Jul 2017

Syntheses of 3,4- and 1,4-dihydroquinazolines from 2-aminobenzylamine

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

Beilstein J. Org. Chem. 2017, 13, 1470–1477, doi:10.3762/bjoc.13.145

Graphical Abstract
  • microwave irradiation at 110 ºC for 4 minutes. Due to the easier preparation and the inexpensive reagents required for its synthesis [65], PPE was chosen as cyclodehydrating agent for the preparation of compounds 1. Results and optimized experimental conditions of the MW-assisted ring-closure reaction are
  • 5a with PPE/CHCl3 under microwave irradiation led to 1,4-dihydroquinazoline 2a, accompanied by a low percentage of a collateral product. This compound was identified as 2-methyl-1-propylquinazolin-4(1H)-one (6a) (Scheme 3, (a), R1 = Pr, R2 = Me), arising from spontaneous benzylic oxidation of 2a. An
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Published 27 Jul 2017

1-Imidoalkylphosphonium salts with modulated Cα–P+ bond strength: synthesis and application as new active α-imidoalkylating agents

  • Jakub Adamek,
  • Roman Mazurkiewicz,
  • Anna Węgrzyk and
  • Karol Erfurt

Beilstein J. Org. Chem. 2017, 13, 1446–1455, doi:10.3762/bjoc.13.142

Graphical Abstract
  • arenes can be markedly facilitated using 1-imidoalkylphosphonium salts derived from triarylphosphines with electron-withdrawing substituents such as tris(m-chorophenyl)phosphine, tris(p-chlorophenyl)phosphine and tris[p-(trifluoromethyl)phenyl]phosphine. Microwave irradiation also considerably
  • does not exert an impact on the reaction rate. As expected, microwave irradiation effectively facilitates the splitting of the highly polar Cα–P+ bond. In order to reduce the Cα–P+ bond strength, and to facilitate the generation of the corresponding 1-imidocarbenium cation, 1-imidoalkylphosphonium
  • (5e) and 1-phthalimido-1-phenylmethyltris[p-(trifluoromethyl)phenyl]phosphonium tetrafluoroborate (5h) already react with anisole at 90 °C (Table 3, entries 5 and 10) and even at 60 °C when using microwave irradiation (Table 3, entry 7); the reaction of 5e with 1,3-dimethoxybenzene started at 80 °C
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Published 24 Jul 2017

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

  • Olga Bakulina,
  • Alexander Ivanov,
  • Vitalii Suslonov,
  • Dmitry Dar’in and
  • Mikhail Krasavin

Beilstein J. Org. Chem. 2017, 13, 1413–1424, doi:10.3762/bjoc.13.138

Graphical Abstract
  • with HPA either at rt or at reflux temperature in acetonitrile or toluene. Attempts to trigger the reaction with these substrates by excluding solvent altogether [34] or applying microwave irradiation (up to 2 h at 200 °C in MeCN) were also unsuccessful. Any appreciable conversion led to predominant
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Published 18 Jul 2017

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

  • A. Michael Downey and
  • Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

Graphical Abstract
  • -glucose in the presence of HCl to provide the methyl glycoside (pathway a, Scheme 6). The reaction proceeds chemoselective at the anomeric position. More recent examples typically use Lewis acids [29][30][31][32][33][34] or microwave irradiation [35][36] to accelerate the reaction. However, shortcomings
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Published 27 Jun 2017

Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds

  • M. Fernanda N. N. Carvalho,
  • Rudolf Herrmann and
  • Gabriele Wagner

Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122

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  • applied, but CDCl3 was used as solvent. Within 10 hours, compound 21a converts cleanly into product 22a without the observation of intermediates or side products. Under microwave irradiation, the reaction is complete within 30 min at 80 °C, without impairing the selectivity. The structure of 22a is
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Published 26 Jun 2017

Ultrasound-promoted organocatalytic enamine–azide [3 + 2] cycloaddition reactions for the synthesis of ((arylselanyl)phenyl-1H-1,2,3-triazol-4-yl)ketones

  • Gabriel P. Costa,
  • Natália Seus,
  • Juliano A. Roehrs,
  • Raquel G. Jacob,
  • Ricardo F. Schumacher,
  • Thiago Barcellos,
  • Rafael Luque and
  • Diego Alves

Beilstein J. Org. Chem. 2017, 13, 694–702, doi:10.3762/bjoc.13.68

Graphical Abstract
  • organic synthesis (sonochemistry) is well documented and is generally considered as an environmentally sound energy source, comparatively less energy intensive to conventional heating and microwave irradiation, also able to reduce the number and quantities of side reaction products [62][63][64][65][66][67
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Published 11 Apr 2017

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

  • Stephen Hill and
  • M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

Graphical Abstract
  • tuneable synthesis of FCDs by selecting a different inorganic ion and carbohydrate combinations using microwave irradiation as the heating source, demonstrating that both the starting material and dehydrating agent of choice can allow tuning/manipulation of the fluorescence properties of the system [31
  • stabilised. Hence a turn-on of the CD fluorescence is indicative of enzyme activity. More recently, Galan et al. reported the 3 min one-step synthesis of blue-emitting CDs from glucosamine hydrochloride in the presence of TTDDA using microwave irradiation with QYs of up to 17% (Scheme 16) [46]. While most
  • selected area electron diffraction (SAED) in the TEM analysis of the CD surface. CDs from chitosan hydrogels have also been reported by Chowdhury et al. [55]. The hydrogels were synthesised from a mixture of acetic acid, glycerol and chitosan, as a more stable starting material for CDs. Microwave
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Published 10 Apr 2017

N-Propargylamines: versatile building blocks in the construction of thiazole cores

  • S. Arshadi,
  • E. Vessally,
  • L. Edjlali,
  • R. Hosseinzadeh-Khanmiri and
  • E. Ghorbani-Kalhor

Beilstein J. Org. Chem. 2017, 13, 625–638, doi:10.3762/bjoc.13.61

Graphical Abstract
  • of p-toluenesulfonic acid (PTSA) as catalyst under microwave irradiation was developed by Castagnolo et al. Following this route, several 4-substituted 5-methylthiazol-2-amines 22 were synthesized from terminal N-propargylamines 20 and isothiocyanates 21 in DMF at 160 °C. Interestingly, when internal
  • syntheses of a series of multiply substituted thiazolidines 33 via the cyclization reaction of secondary N-propargylamines 32 with blocked N-isothiocyanate precursors 31. The desired N-isocyanates A are produced in situ upon heating or treatment with a base, in acetonitrile under microwave irradiation
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Published 30 Mar 2017

Transition-metal-catalyzed synthesis of phenols and aryl thiols

  • Yajun Liu,
  • Shasha Liu and
  • Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

Graphical Abstract
  • catalyzed protocol for converting aryl halides to phenols [45]. Aided by 200 W microwave irradiation, the conversion was accomplished within 40 minutes in the presence of (n-Bu)4NBr and KOH (Scheme 21). Using this reaction system, moderate yields of phenols could be obtained from both aryl iodides and aryl
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Published 23 Mar 2017

NMR reaction monitoring in flow synthesis

  • M. Victoria Gomez and
  • Antonio de la Hoz

Beilstein J. Org. Chem. 2017, 13, 285–300, doi:10.3762/bjoc.13.31

Graphical Abstract
  • -deuterated solvents. This result showed how the synergistic interaction of microwave irradiation as the energy source and the rapid reaction characterization available with NMR and flow techniques can be used for rapid optimization in a single experiment in short time and with very small solvent volumes
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Published 14 Feb 2017

Synthesis of spiro[isoindole-1,5’-isoxazolidin]-3(2H)-ones as potential inhibitors of the MDM2-p53 interaction

  • Salvatore V. Giofrè,
  • Santa Cirmi,
  • Raffaella Mancuso,
  • Francesco Nicolò,
  • Giuseppe Lanza,
  • Laura Legnani,
  • Agata Campisi,
  • Maria A. Chiacchio,
  • Michele Navarra,
  • Bartolo Gabriele and
  • Roberto Romeo

Beilstein J. Org. Chem. 2016, 12, 2793–2807, doi:10.3762/bjoc.12.278

Graphical Abstract
  • -dipolar cycloaddition in toluene at 110 °C for 4 h, under microwave irradiation: cycloadducts 6a–e have been isolated in 38–60% yield, as major isomers, together with isomers 7 as minor adducts and unreacted isoindolinones 2a–e mainly in E configuration (Scheme 2, Table 1). The cycloaddition reaction of
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Published 20 Dec 2016

Electron-transfer-initiated benzoin- and Stetter-like reactions in packed-bed reactors for process intensification

  • Anna Zaghi,
  • Daniele Ragno,
  • Graziano Di Carmine,
  • Carmela De Risi,
  • Olga Bortolini,
  • Pier Paolo Giovannini,
  • Giancarlo Fantin and
  • Alessandro Massi

Beilstein J. Org. Chem. 2016, 12, 2719–2730, doi:10.3762/bjoc.12.268

Graphical Abstract
  • further increase of temperature (100 °C) and the use of microwave irradiation at 120 °C (1 h) were not beneficial for the reaction outcome (Table 2, entries 4 and 5). The model Stetter-like reaction was finally optimized by varying the 1a/9a ratio (Table 2, entries 6 and 7) and the best yield of 10aa (68
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Published 13 Dec 2016

Catalytic Wittig and aza-Wittig reactions

  • Zhiqi Lao and
  • Patrick H. Toy

Beilstein J. Org. Chem. 2016, 12, 2577–2587, doi:10.3762/bjoc.12.253

Graphical Abstract
  • reactions butylene oxide was used as a base precursor, phenylsilane was the reducing reagent, and the reactions were performed using microwave irradiation (MWI). Subsequently, Werner et al. reported the scope and limitations of such microwave-assisted catalytic Wittig reactions using tributylphosphine
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Published 30 Nov 2016

Selective and eco-friendly procedures for the synthesis of benzimidazole derivatives. The role of the Er(OTf)3 catalyst in the reaction selectivity

  • Natividad Herrera Cano,
  • Jorge G. Uranga,
  • Mónica Nardi,
  • Antonio Procopio,
  • Daniel A. Wunderlin and
  • Ana N. Santiago

Beilstein J. Org. Chem. 2016, 12, 2410–2419, doi:10.3762/bjoc.12.235

Graphical Abstract
  • benzaldehyde (1:2 ratio) selectively afforded 1-benzyl-2-phenyl-1H-benzimidazole (1b) (72% yield), using both microwave irradiation and conventional heating for 15 minutes (Table 1, entries 1 and 3). In the absence of the catalyst, the same reaction afforded a mixture of products 1a and 1b using both
  • conditions. Namely, under microwave irradiation, 41% of 1a and 51% of 1b were formed (Table 1, entry 2). While, using conventional heating, 52% of 1a and 40% of 1b were formed (Table 1, entry 4). To shorten the reaction time, the catalyzed reaction was carried out during 5 minutes at room temperature. Using
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Published 16 Nov 2016

Experimental and theoretical investigations into the stability of cyclic aminals

  • Edgar Sawatzky,
  • Antonios Drakopoulos,
  • Martin Rölz,
  • Christoph Sotriffer,
  • Bernd Engels and
  • Michael Decker

Beilstein J. Org. Chem. 2016, 12, 2280–2292, doi:10.3762/bjoc.12.221

Graphical Abstract
  • structures with various applications in medicinal chemistry [20][21]. The syntheses of tetrahydroquinazolines are well described using different approaches: the majority relies on the direct α-amination of o-aminobenzaldehydes with heating or microwave irradiation [22][23][24], by condensation of diamines
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Published 31 Oct 2016

Stereoselective synthesis of fused tetrahydroquinazolines through one-pot double [3 + 2] dipolar cycloadditions followed by [5 + 1] annulation

  • Xiaofeng Zhang,
  • Kenny Pham,
  • Shuai Liu,
  • Marc Legris,
  • Alex Muthengi,
  • Jerry P. Jasinski and
  • Wei Zhang

Beilstein J. Org. Chem. 2016, 12, 2204–2210, doi:10.3762/bjoc.12.211

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  • microwave irradiation at 115 °C for 25 min. Upon the completion of the reaction as monitored by LC–MS, maleimide 6 (1.0 mmol) was added to the reaction mixture and then heated by microwave irradiation at 125 °C for 25 min. The concentrated reaction mixture was isolated on a semi-preparative HPLC with a C18
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Published 18 Oct 2016

Microwave-assisted cyclizations promoted by polyphosphoric acid esters: a general method for 1-aryl-2-iminoazacycloalkanes

  • Jimena E. Díaz,
  • María C. Mollo and
  • Liliana R. Orelli

Beilstein J. Org. Chem. 2016, 12, 2026–2031, doi:10.3762/bjoc.12.190

Graphical Abstract
  • sensitive substrates. Results and Discussion The ω-arylaminonitrile precursors were obtained by reaction of the corresponding ω-halonitrile and arylamines, as previously reported by our group [44]. We examined first the cyclization of 4-(p-tolylamino)butyronitrile (1a) with PPE under microwave irradiation
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Published 14 Sep 2016

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

  • Adrian E. Ion,
  • Liliana Cristian,
  • Mariana Voicescu,
  • Masroor Bangesh,
  • Augustin M. Madalan,
  • Daniela Bala,
  • Constantin Mihailciuc and
  • Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

Graphical Abstract
  • high temperature and pressure, they decompose very rapidly. Alternatively, the chalcones 2 can be isolated following the conventional synthetic route, namely the reaction of equimolar amounts of the azulene-carbaldehyde with 2-acetylpyridine in ethanol, at room temperature or, by microwave irradiation
  • reacted with excess ammonium acetate in acetic acid under microwave irradiation at 160 °C for 5 minutes. The target terpyridines are isolated in satisfactory yields varying from 42% in the case of compound 4a to 35% for 4b, respectively. If the reaction is performed under refluxing conditions for 4–6
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Published 11 Aug 2016

Experimental and theoretical insights in the alkene–arene intramolecular π-stacking interaction

  • Valeria Corne,
  • Ariel M. Sarotti,
  • Carmen Ramirez de Arellano,
  • Rolando A. Spanevello and
  • Alejandra G. Suárez

Beilstein J. Org. Chem. 2016, 12, 1616–1623, doi:10.3762/bjoc.12.158

Graphical Abstract
  • chemical transformations under microwave irradiation [17], affording the cycloadducts 3a,b in very good yields (76–81%) after irradiating a THF solution of 1 and 2 at 150 °C during 4 hours. The reduction of the ketone group in 3 with NaBH4 produced alcohols 4 and 5 in excellent yields and a ratio of about
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Published 28 Jul 2016

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

  • Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

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  • afforded the desired isoindolin-1-one-3-phosphonates 60 in only 14% yields after five days. Noteworthy, the treatment of the same reaction mixture under microwave irradiation at 90 °C gave the expected product 60 in 77% yields after several minutes. Subsequently, the isoindolin-1-one-3-phosphonates 60 were
  • phosphorylated quinazoline 203 through reductive elimination. A silver-catalyzed three-component reaction of α-isocyanophosphonates 206, ketones 205 and amines 204 under microwave irradiation to afford (2-imidazolin-4-yl)phosphonates 210 has recently been reported (Scheme 43) [81]. The yields of the products
  • corresponding products 271 and 272 were isolated in 52–61% yields and their nOe analysis revealed the geometry of the alkene bonds to be E . A tandem 1,4–1,2 addition of dimethyl trimethylsilyl phosphite (DMPTMS, 273) to diazaheterocyclic compounds under microwave irradiation in acidic medium led to
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Published 21 Jun 2016

Stereoselective synthesis of tricyclic compounds by intramolecular palladium-catalyzed addition of aryl iodides to carbonyl groups

  • Jakub Saadi,
  • Christoph Bentz,
  • Kai Redies,
  • Dieter Lentz,
  • Reinhold Zimmer and
  • Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1236–1242, doi:10.3762/bjoc.12.118

Graphical Abstract
  • sample of 5b afforded compound 15b in 45% yield as a single isomer. These results were obtained employing microwave irradiation (400 W) that allowed considerably shorter reaction times, however, the yields were not strongly influenced by this modification. From both product diastereomers crystals
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Published 16 Jun 2016

Enabling technologies and green processes in cyclodextrin chemistry

  • Giancarlo Cravotto,
  • Marina Caporaso,
  • Laszlo Jicsinszky and
  • Katia Martina

Beilstein J. Org. Chem. 2016, 12, 278–294, doi:10.3762/bjoc.12.30

Graphical Abstract
  • CD derivatives. Several examples of sonochemical selective modification of native α-, β- and γ-CDs have been reported including heterogeneous phase Pd- and Cu-catalysed hydrogenations and couplings. Microwave irradiation has emerged as the technique of choice for the production of highly substituted
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Published 15 Feb 2016
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