Clicked and long spaced galactosyl- and lactosylcalix[4]arenes: new multivalent galectin-3 ligands

• Silvia Bernardi,
• Paola Fezzardi,
• Gabriele Rispoli,
• Stefania E. Sestito,
• Francesco Peri,
• Francesco Sansone and
• Alessandro Casnati

Beilstein J. Org. Chem. 2014, 10, 1672–1680, doi:10.3762/bjoc.10.175

• between the tetraalkyne calix[4]arene 8 and azido-galactoside 5 to give glycocluster 9 (83% yield) was carried out in DMF and H2O with CuSO4 and sodium ascorbate following a microwave-assisted procedure (20 min, 150 W, 80 °C). No partially functionalized compounds or other byproducts were detected in the

Multichromophoric sugar for fluorescence photoswitching

• Stéphane Maisonneuve,
• Rémi Métivier,
• Pei Yu,
• Keitaro Nakatani and
• Juan Xie

Beilstein J. Org. Chem. 2014, 10, 1471–1481, doi:10.3762/bjoc.10.151

• systems [17]. In order to introduce three DCM fluorophores and one photochromic species into the glycopyranoside scaffold, methyl 6-O-trityl-α-D-glucopyranoside 3 was chosen as starting material (Scheme 1). O-Propargylation followed by microwave-assisted CuAAC with azido-functionalized DCM fluorophore 5

• [25] in the presence of copper sulfate and sodium ascorbate led to the fluorescent glucoside 6. The trityl group was then removed by a catalytic amount of acetyl chloride in a mixture of MeOH and CH2Cl2. Subsequent activation as mesylated followed by “microwave-assisted” nucleophilic substitution with

Pd/C-catalyzed aerobic oxidative esterification of alcohols and aldehydes: a highly efficient microwave-assisted green protocol

• Marina Caporaso,
• Giancarlo Cravotto,
• Spyros Georgakopoulos,
• George Heropoulos,
• Katia Martina and
• Silvia Tagliapietra

Beilstein J. Org. Chem. 2014, 10, 1454–1461, doi:10.3762/bjoc.10.149

• friendly microwave-assisted oxidative esterification of alcohols and aldehydes in the presence of molecular oxygen and a heterogeneous catalysis (Pd/C, 5 mol %). This efficient and ligandless conversion procedure does not require the addition of an organic hydrogen acceptor. The reaction rate is strongly

Microwave-assisted Cu(I)-catalyzed, three-component synthesis of 2-(4-((1-phenyl-1H-1,2,3-triazol-4-yl)methoxy)phenyl)-1H-benzo[d]imidazoles

• Yogesh Kumar,
• Vijay Bahadur,
• Anil K. Singh,
• Virinder S. Parmar,
• Erik V. Van der Eycken and
• Brajendra K. Singh

Beilstein J. Org. Chem. 2014, 10, 1413–1420, doi:10.3762/bjoc.10.145

• Yogesh Kumar Vijay Bahadur Anil K. Singh Virinder S. Parmar Erik V. Van der Eycken Brajendra K. Singh Bioorganic Laboratory, Department of Chemistry, University of Delhi, Delhi 110 007, India Laboratory for Organic & Microwave-Assisted Chemistry (LOMAC), Department of Chemistry, University of

• Leuven (KU Leuven), Celestijnenlaan 200F, B-3001 Leuven, Belgium 10.3762/bjoc.10.145 Abstract A microwave-assisted synthesis of 2-(4-((1-phenyl-1H-1,2,3-triazol-4-yl)methoxy)phenyl)-1H-benzo[d]imidazoles from a phenylazide, propargyloxybenzaldehyde and a 1,2-diaminobenzene is proposed. Keywords

• : benzimidazole; Cu(I) catalysis; microwave-assisted synthesis; multicomponent; three component synthesis; Introduction Due to their structural range and biological importance nitrogen-containing heterocycles have been striking targets for many years. They are found in a variety of natural products and are

Synthesis of the first examples of iminosugar clusters based on cyclopeptoid cores

• Mathieu L. Lepage,
• Alessandra Meli,
• Anne Bodlenner,
• Céline Tarnus,
• Francesco De Riccardis,
• Irene Izzo and
• Philippe Compain

Beilstein J. Org. Chem. 2014, 10, 1406–1412, doi:10.3762/bjoc.10.144

• microwave-assisted CuAAC reaction (Scheme 2). The multiconjugation reaction proceeded smoothly to afford the six desired DNJ clusters 9 in 69–95% yields. With the exception of octavalent iminosugars 9c (n = 6) and 9d (n = 9), these compounds showed complex 1H NMR spectra at room temperature as exemplified

Design and synthesis of multivalent neoglycoconjugates by click conjugations

• Feiqing Ding,
• Li Ji,
• Ronny William,
• Hua Chai and
• Xue-Wei Liu

Beilstein J. Org. Chem. 2014, 10, 1325–1332, doi:10.3762/bjoc.10.134

• irradiation, which is best known to accelerate transition metal-catalyzed homogeneous reactions [54]. Microwave-assisted organic reactions are rapidly becoming recognized as a valuable tool for facilitating a wide variety of organic transformations [55][56]. Finally, we found that the rate of conversion

Automated solid-phase peptide synthesis to obtain therapeutic peptides

• Veronika Mäde,
• Sylvia Els-Heindl and
• Annette G. Beck-Sickinger

Beilstein J. Org. Chem. 2014, 10, 1197–1212, doi:10.3762/bjoc.10.118

• essentially improved microwave-assisted instruments is discussed. In order to improve pharmacokinetic properties of peptides, lipidation and PEGylation are described as covalent conjugation methods, which can be applied by a combination of automated and manual synthesis approaches. The synthesis and

• peptides are covered with a focus on Fmoc (9-fluorenylmethoxycarbonyl)/t-Bu (tert-butyl)-based solid-phase peptide synthesis. Recent advances in automation devices are described, with attention to the comparison between conservative SPPS robots and microwave-assisted automated SPPS. Moreover, strategies

• influenced by the length and complexity of the desired peptides. Difficult and larger peptides often lead to impurities, synthesis termination and finally low yields owing to inter- and intramolecular aggregation and sterical hindrance. To reduce these effects, microwave-assisted instruments have been

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• several authors for the phosphination of a large variety of compounds [180][181][182][183][184][185][186][187][188]. Microwave-assisted procedures have also been developed [189][190][191]. Kwong et al. implemented a palladium-catalyzed phosphination of aryl bromides and triflates 104 with

Consecutive isocyanide-based multicomponent reactions: synthesis of cyclic pentadepsipeptoids

• Angélica de Fátima S. Barreto,
• Otilie E. Vercillo,
• Ludger A. Wessjohann and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2014, 10, 1017–1022, doi:10.3762/bjoc.10.101

• structures are outlined in Figure 2. Results and Discussion In continuing our research on the synthesis of peptoids with potential pharmacological activity [12][17][18][44][45] and using a fast and efficient microwave-assisted synthesis of peptoids [15][17][18], we decided to carry out the synthesis of

• depsipeptoid analogues of San A based on a strategy developed in our groups for the synthesis of cyclic RGD pentapeptoids [44]. This strategy was adapted by a combination of microwave-assisted Ugi and Passerini reactions. It is also important to highlight that the synthesis of cyclic depsipeptoids had not been

Phosphinate-containing heterocycles: A mini-review

• Olivier Berger and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2014, 10, 732–740, doi:10.3762/bjoc.10.67

• . Selected recent synthetic work by us and others is presented below. Review Phospholes Several compounds have been prepared in this series. Keglevich and coworkers realized the synthesis of phosphole derivatives 2a–f based on the McCormack reaction [10] followed by microwave-assisted esterification of the

Rapid pseudo five-component synthesis of intensively blue luminescent 2,5-di(hetero)arylfurans via a Sonogashira–Glaser cyclization sequence

• Fabian Klukas,
• Alexander Grunwald,
• Franziska Menschel and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 672–679, doi:10.3762/bjoc.10.60

• delocalized over the whole molecule (Figure 3), which plausibly rationalizes the high extinction coefficient of the longest wavelength absorptions bands. Conclusion In summary we have disclosed a concise and efficient microwave-assisted pseudo five-component synthesis of symmetrical 2,5-di(hetero)arylfurans

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

Simple two-step synthesis of 2,4-disubstituted pyrroles and 3,5-disubstituted pyrrole-2-carbonitriles from enones

• Murat Kucukdisli,
• Dorota Ferenc,
• Marcel Heinz,
• Christine Wiebe and
• Till Opatz

Beilstein J. Org. Chem. 2014, 10, 466–470, doi:10.3762/bjoc.10.44

• -carbonitriles. Keywords: α-aminonitriles; cyclization; heterocycles; microwave-assisted synthesis; pyrroles; Introduction Heterocycles are the largest class of organic compounds [1]. Among them, pyrroles have a distinguished position in the chemistry of living organisms due to their close biogenetic

• or ketones [23]. The most practical approach to a 2,4-disubstituted pyrrole reported to date is the recently disclosed microwave-assisted Stetter reaction of chalcone with carbohydrates as “green” formaldehyde equivalents followed by a microwave-assisted Paal–Knorr cyclization of the resulting 1,4

• pyrroles and 3,5-disubstituted pyrrole-2-carbonitriles by means of a cyclocondensation with aminoacetonitrile and a microwave-assisted dehydrocyanation or a dehydrogenation with DDQ. These methods provide a simple an efficient entry into these useful compound classes. Experimental Typical procedure for the

Stereoselectively fluorinated N-heterocycles: a brief survey

• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2013, 9, 2696–2708, doi:10.3762/bjoc.9.306

• ]-Wittig rearrangement, a diastereoselective epoxidation, and a microwave assisted transannular epoxide opening reaction. It is also noteworthy that the starting material 55 contains an extraneous fluorine atom which is deleted during the synthetic sequence; this approach takes advantage of the often low

Microwave-assisted synthesis of 5,6-dihydroindolo[1,2-a]quinoxaline derivatives through copper-catalyzed intramolecular N-arylation

• Fei Zhao,
• Lei Zhang,
• Hailong Liu,
• Shengbin Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2013, 9, 2463–2469, doi:10.3762/bjoc.9.285

• moderate yields. In this study, we tried to overcome these limitations by using copper-catalyzed C–N coupling and microwave-assisted organic synthesis, and we present an efficient and practical protocol, which rapidly synthesized 5,6-dihydroindolo[1,2-a]quinoxaline derivatives by copper-catalyzed

• toluene at 110 °C heated in an oil bath for 10 h. Unfortunately, most of the substrate 1a was recovered (Table 1, entry 1) and the desired product was obtained only in low yield (38%). Considering that microwave-assisted organic synthesis (MAOS) is time- and energy-saving [43][44][45], we then chose this

Synthetic scope and DFT analysis of the chiral binap–gold(I) complex-catalyzed 1,3-dipolar cycloaddition of azlactones with alkenes

• María Martín-Rodríguez,
• Luis M. Castelló,
• Carmen Nájera,
• José M. Sansano,
• Olatz Larrañaga,
• Abel de Cózar and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2013, 9, 2422–2433, doi:10.3762/bjoc.9.280

• needed using other synthetic strategies [43]. Pyrrolines also possess a typical 1,3-dipole precursor structure (azomethine ylide), so a second cycloaddition was attempted with a new equivalent of N-methylmaleimide. The reaction took place under microwave assisted heating (1 h, 75 W) using triethylamine

• experiments supported the drawn absolute configuration of 15. Other different dipolarophiles were attempted to react with starting 7aa obtaining very complex mixtures including decomposed materials. In the most cases, reactions had to be refluxed for 24 h (110 °C, toluene) because microwave assisted

One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger–aza-Wittig reaction

• Diego Carnaroglio,
• Katia Martina,
• Giovanni Palmisano,
• Andrea Penoni,
• Claudia Domini and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2013, 9, 2378–2386, doi:10.3762/bjoc.9.274

• : isocyanates; microwave-assisted reaction; one-pot reaction; tandem Staudinger–aza-Wittig reaction; urea derivatives; Introduction The industrial and commercial impact of isocyanates (R–NCO) is steadily growing. In particular, the polyurethane output has undergone yearly increases of 5% over the last decade

Post-Ugi gold-catalyzed diastereoselective domino cyclization for the synthesis of diversely substituted spiroindolines

• Amit Kumar,
• Dipak D. Vachhani,
• Sachin G. Modha,
• Sunil K. Sharma,
• Virinder S. Parmar and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2013, 9, 2097–2102, doi:10.3762/bjoc.9.246

• Amit Kumar Dipak D. Vachhani Sachin G. Modha Sunil K. Sharma Virinder S. Parmar Erik V. Van der Eycken Laboratory for Organic & Microwave-Assisted Chemistry (LOMAC), Department of Chemistry, University of Leuven (KU Leuven), Celestijnenlaan 200F, 3001, Leuven, Belgium Bioorganic Laboratory

Acid, silver, and solvent-free gold-catalyzed hydrophenoxylation of internal alkynes

• Marcia E. Richard,
• Daniel V. Fraccica,
• Kevin J. Garcia,
• Erica J. Miller,
• Rosa M. Ciccarelli,
• Erin C. Holahan,
• Victoria L. Resh,
• Aakash Shah,
• Peter M. Findeis and
• Robert A. Stockland Jr.

Beilstein J. Org. Chem. 2013, 9, 2002–2008, doi:10.3762/bjoc.9.235

• reactor (Scheme 1) [14]. Although microwave-assisted reactions are legion in organic chemistry, they are rare in organometallic synthesis [15][16][17][18][19][20][21]. Our initial report on this chemistry was focused on gold compounds bearing Buchwald-type phosphine ligands such as JohnPhos and t-BuXPhos

• vinyl ethers. After a bit of experimentation, it was observed that 1 afforded the highest conversions in microwave-assisted reactions, while 7 generated the highest yields in conventionally heated reactions. The addition reaction was tolerant of both electron-withdrawing and electron-donating groups

• using 1H–1H NOESY experiments. All coupling constants are listed in Hertz. Microwave-assisted reactions were carried out in sealed vessels using a CEM Discover equipped with an external IR (surface) temperature sensor. The PowerMax setting on the Discover was off. Conventionally heated reactions were

One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor

• Mark C. Bagley,
• Vincenzo Fusillo,
• Robert L. Jenkins,
• M. Caterina Lubinu and
• Christopher Mason

Beilstein J. Org. Chem. 2013, 9, 1957–1968, doi:10.3762/bjoc.9.232

• dihydropyridine synthesis; heterocycles; microwave synthesis; multicomponent reactions; pyridine synthesis; Introduction Microwave-assisted synthesis has revolutionized many processes in recent years as a valuable alternative to the use of conductive heating for accelerating transformations in synthetic organic

• an encapsulated palladium catalyst by Baxendale and Ley, et al. [25], the latter to process multigram quantities in a microwave-assisted Suzuki–Miyaura coupling. A comparison on the use of palladium(0) nanoparticle catalysts on glass-polymer composite materials in batch and flow-through experiments

• microwave-assisted transformations under flow processing have greatly expanded the range of chemistries scaled up and evaluated using this technology [1][9][16][33][34][35][36][37][38][39][40][41][42]. With all of these developments, it is becoming increasingly clear that flow chemistry, and to some degree

Superstructures of fluorescent cyclodextrin via click-reaction

• Arkadius Maciollek,
• Helmut Ritter and
• Rainer Beckert

Beilstein J. Org. Chem. 2013, 9, 827–831, doi:10.3762/bjoc.9.94

• of the measured intensity autocorrelation function of the sample by a General Purpose Method (non-negative least squares) algorithm included in the DTS software. Microwave-assisted synthesis was performed using a CEM Discover Synthesis Unit (monomode system). The temperature was measured by infrared

End-labeled amino terminated monotelechelic glycopolymers generated by ROMP and Cu(I)-catalyzed azide–alkyne cycloaddition

• Ronald Okoth and
• Amit Basu

Beilstein J. Org. Chem. 2013, 9, 608–612, doi:10.3762/bjoc.9.66

• of the NHS esters had indeed been displaced. CuAAC between propargyl β-D-galactoside 10a [23] and azido polymer 9 was achieved in 10 minutes by a microwave-assisted protocol to give galactosyl polymer 11a. We also prepared the mannosylated glycopolymer 11b in a similar manner (see Supporting

Polymerization of novel methacrylated anthraquinone dyes

• Christian Dollendorf,
• Susanne Katharina Kreth,
• Soo Whan Choi and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 453–459, doi:10.3762/bjoc.9.48

• green-colored double-substituted intermediate 5,8-bis(4-(2-hydroxyethyl)phenylamino)-1,4-dihydroxyanthraquinone (1) in 50% overall yield. According to the literature, reactions can be accelerated with improved yields by microwave assistance [28][29]. After microwave-assisted methacrylation with

Microwave-assisted three-component domino reaction: Synthesis of indolodiazepinotriazoles

• Rajesh K. Arigela,
• Sudhir K. Sharma,
• Brijesh Kumar and
• Bijoy Kundu

Beilstein J. Org. Chem. 2013, 9, 401–405, doi:10.3762/bjoc.9.41

• Abstract A microwave-assisted three-component protocol involving N-1 alkylation of 2-alkynylindoles with epichlorohydrin, ring opening of the epoxide with sodium azide, and an intramolecular Huisgen azide–internal alkyne 1,3-dipolar cycloaddition domino sequence has been described. The efficacy of the

• intramolecular 1,3-dipolar cycloaddition pathway and in turn lead to the sequential formation of 7- or 5-membered diazepine and triazole rings in a single step. In this communication, we report a versatile microwave-assisted three component domino reaction to furnish annulated tetracyclic

New enzymatically polymerized copolymers from 4-tert-butylphenol and 4-ferrocenylphenol and their modification and inclusion complexes with β-cyclodextrin

• Adam Mondrzyk,
• Beate Mondrzik,
• Sabrina Gingter and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 2118–2123, doi:10.3762/bjoc.8.238

• measured intensity autocorrelation function of the sample by the general purpose method (non-negative least squares) algorithm included in the DTS software. Each experiment was performed at least five times. Microwave-assisted synthesis was performed by using a CEM Discover synthesis unit (monomode system