Aerobic addition of secondary phosphine oxides to vinyl sulfides: a shortcut to 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl)phosphine oxides

• Svetlana F. Malysheva,
• Alexander V. Artem’ev,
• Nina K. Gusarova,
• Nataliya A. Belogorlova,
• Alexander I. Albanov,
• C. W. Liu and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2015, 11, 1985–1990, doi:10.3762/bjoc.11.214

• Chemistry, National Dong Hwa University, Hualien 97401, Taiwan 10.3762/bjoc.11.214 Abstract Secondary phosphine oxides react with vinyl sulfides (both alkyl- and aryl-substituted sulfides) under aerobic and solvent-free conditions (80 °C, air, 7–30 h) to afford 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl

• addition of P–H species to the C=C bonds readily proceeds in the absence of any catalyst or initiator (Scheme 1). The reactions occur under mild solvent-free conditions (70–80 °C, inert atmosphere, 3–15 h) to chemo- and regioselectively furnish the anti-Markovnikov adducts in excellent yields (up to 99

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

• Yuri A. Rulev,
• Zalina Gugkaeva,
• Victor I. Maleev,
• Michael North and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2015, 11, 1614–1623, doi:10.3762/bjoc.11.176

• salts and increasing the steric hindrance around the ammonium salts. Herein, we report the synthesis of two aluminium–salen complexes incorporating quaternary ammonium salts directly attached to the salen ligand and their catalytic activities for the coupling of epoxides and carbon dioxide under solvent

• free conditions. Catalyst recycling experiments are also reported and show the robustness of this system. Results and Discussion The preparation of salen ligands 8a and 8b was conducted according to Scheme 2, starting from tert-butylphenol, which was formylated and then nitrated to produce 5-nitro-3

Synthesis of alpha-tetrasubstituted triazoles by copper-catalyzed silyl deprotection/azide cycloaddition

• Zachary L. Palchak,
• Paula T. Nguyen and
• Catharine H. Larsen

Beilstein J. Org. Chem. 2015, 11, 1425–1433, doi:10.3762/bjoc.11.154

• Scheme 1 would streamline the synthesis of alpha-tetrasubstituted triazoles 6. In the first step, our solvent-free copper-catalyzed three-component coupling of cyclohexanone (1), amines 2, and alkynes 3 provides high yields of silyl-protected propargylic amines 4 [24][25]. Trimethylsilyl (TMS) acetylene

Single-molecule conductance of a chemically modified, π-extended tetrathiafulvalene and its charge-transfer complex with F₄TCNQ

• Raúl García,
• M. Ángeles Herranz,
• Edmund Leary,
• M. Teresa González,
• Gabino Rubio Bollinger,
• Marius Bürkle,
• Linda A. Zotti,
• Yoshihiro Asai,
• Fabian Pauly,
• Juan Carlos Cuevas,
• Nicolás Agraït and
• Nazario Martín

Beilstein J. Org. Chem. 2015, 11, 1068–1078, doi:10.3762/bjoc.11.120

• a clean gold substrate to the solution for a period of approximately 30 min. The sample was then dried under a flow of argon and mounted inside the scanning tunneling microscope (STM). All experiments were then performed under solvent-free, ambient conditions. In order to form molecular junctions of

• -dithiol compound (where 3 indicates the total number of phenyl rings), in which the central phenyl ring has been substituted by an exTTF unit. We could, therefore, expect compound 5 to form molecular junctions in a similar way to the OPE3-dithiol, which readily does so either in solution, or under solvent

• -free conditions as recently reported [27]. Hence, as a starting point, we followed the same sample preparation conditions as previously with the OPE3-dithiol [27]. We prepared 0.1–1 mM solutions of compound 5 in both 1,2,4-trichlorobenzene (TCB) or mesitylene/tetrahydrofuran (Mes/THF 4:1), and exposed

Properties of PTFE tape as a semipermeable membrane in fluorous reactions

• Brendon A. Parsons,
• Olivia Lin Smith,
• Myeong Chae and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2015, 11, 980–993, doi:10.3762/bjoc.11.110

• streams of dense dimethyl phthalate solution as it diffuses through PTFE tape and pools at the bottom of the vial. Solvent-free diffusion of bromine through PTFE tape Solvent-free diffusion of bromine through PTFE tape was observed when a PV-PTFE bromination was carried out in the absence of a solvent on

• solvent. The delivery tube was inserted into the flask so that the lower tip of the delivery tube was immersed in the solvent. This process was repeated in triplicate with each solvent. Solvent-free diffusion of bromine through PTFE tape A single drop of bromine was placed on two sections of an aluminum

On the strong difference in reactivity of acyclic and cyclic diazodiketones with thioketones: experimental results and quantum-chemical interpretation

• Andrey S. Mereshchenko,
• Alexey V. Ivanov,
• Viktor I. Baranovskii,
• Grzegorz Mloston,
• Ludmila L. Rodina and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2015, 11, 504–513, doi:10.3762/bjoc.11.57

• diazo compounds 1a–f with cycloaliphatic thioketone 2b were calculated (Table 2). All calculations refer to the gas phase, since all reactions of DDC 1 with the thioxocyclobutanedione 2b were carried out under solvent-free conditions [20]. The driving force behind the DDC 1a–d reactions with

Binding mode and free energy prediction of fisetin/β-cyclodextrin inclusion complexes

• Bodee Nutho,
• Wasinee Khuntawee,
• Chompoonut Rungnim,
• Piamsook Pongsawasdi,
• Peter Wolschann,
• Alfred Karpfen,
• Nawee Kungwan and
• Thanyada Rungrotmongkol

Beilstein J. Org. Chem. 2014, 10, 2789–2799, doi:10.3762/bjoc.10.296

• estimated from a linear relation as: where SASA is the solvent-accessible surface area. The γ and β with the values of 0.00542 kcal/mol·Å2 and 0.92 kcal/mol, respectively, are taken from linear regression of a set of small nonpolar molecules solvent free energy in water [48][51][52]. In addition, the

A green approach to the synthesis of novel phytosphingolipidyl β-cyclodextrin designed to interact with membranes

• Yong Miao,
• Florence Djedaïni-Pilard and
• Véronique Bonnet

Beilstein J. Org. Chem. 2014, 10, 2654–2657, doi:10.3762/bjoc.10.278

• with a promising yield. Keywords: fatty ester; green chemistry; lipase; mono-substituted amphiphilic cyclodextrins; peptide Coupling; solvent-free medium; transesterification; Introduction Cyclodextrins (CDs) are sustainable compounds which are particularly interesting in the frame of pharmaceutical

• time in cyclodextrin chemistry via solvent-free substitution of aminocyclodextrin followed by the use of a new, more environmentally friendly peptide coupling agent known as COMU (1-cyano-2-ethoxy-2-oxoethylidenaminooxy)dimethylaminomorpholinocarbenium hexafluorophosphate). Finally, by optimized

• medium. The mixture was left to react for 10 minutes. The use of TLC indicated the end of the reaction. After the purification, yields of above 70% were obtained. It was indeed observed that solvent-free conditions can be employed in this reaction. The reaction is much faster without solvent due to the

Regio- and stereoselective synthesis of new diaminocyclopentanols

• Evgeni A. Larin,
• Valeri S. Kochubei and
• Yuri M. Atroshchenko

Beilstein J. Org. Chem. 2014, 10, 2513–2520, doi:10.3762/bjoc.10.262

• experiments was performed under solvent-free conditions at 100 °C. In case of morpholine (7a), the best catalytic effect was observed with LiClO4 [36] and Zn(ClO4)2·6H2O [37] affording 56 and 76% yield of 8a after isolation and purification, therefore the absence of the solvent seems crucial for the reaction

• nucleophilicity. Moreover, there was not much effect on the outcome of the reactions conducted either under solvent-free conditions or using DMSO as a solvent. The regioisomers 9a–d and 10a–d were isolated through column chromatographic separation and fully characterized in order to avoid ambiguity. The

• diaminocyclopentanols in good yields. It has been shown that using Zn(ClO4)2·6H2O under solvent-free conditions and Cs2CO3 in DMSO is preferable to the ring opening of di-N-protected cyclopentanamine epoxides. We have highlighted the influence of the nature of the N,N-disubstituted amino moiety and the orientation of

Derivatives of the triaminoguanidinium ion, 3. Multiple N-functionalization of the triaminoguanidinium ion with isocyanates and isothiocyanates

• Jan Szabo,
• Kerstin Karger,
• Nicolas Bucher and
• Gerhard Maas

Beilstein J. Org. Chem. 2014, 10, 2255–2262, doi:10.3762/bjoc.10.234

• halides, tosylates and triflates. In our hands, solvent-free heterogenous mixtures of the solid guanidinium salt and a liquid alkylating reagent did not react as desired. Therefore, we developed a two-step alkylation procedure, by which the catalytic hydrogenation of 1,2,3-tris(benzyliminyl)guanidinium

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• phosphite were carried out under solvent-free conditions at 60 °C (for 14) or at 80 °C (for 27). Products 28 and 29 were obtained in good to excellent yields as 1:1 diastereoisomeric mixtures arising from the generation of a stereogenic center at the aminophosphonate chain. The mixtures were not separated

• was conducted under solvent-free microwave irradiation conditions. Products 114 were isolated by crystallization in yields exceeding 80%. Siddiqui et al. developed the method for the preparation of nucleoside analogs 116 with the 1,3,4-thiadiazole-derived nucleobase. This method involved the microwave

• , microwave irradiation (600 W), 6–10 min (solvent-free conditions). Reagents and reaction conditions: i. Montmorillonite K-10 clay, microwave irradiation (560 W), 6–10 min (solvent-free conditions). Reagents and reaction conditions: i. CeCl3·7H2O (20 mol %), NaI (20 mol %), microwave irradiation (90 °C), 6–8

A complete series of 6-deoxy-monosubstituted tetraalkylammonium derivatives of α-, β-, and γ-cyclodextrin with 1, 2, and 3 permanent positive charges

• Martin Popr,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2014, 10, 1390–1396, doi:10.3762/bjoc.10.142

• modified procedure described by Tabushi et al. [33] (for β-CD only), which is a solvent-free reaction of the monotosylate with an excess of liquid triamine. The unreacted liquid triamine can be recovered from the reaction mixture by vacuum distillation and used repeatedly. Pure intermediates 27 and 28 were

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

• also been shown to take place at room temperature in the absence of a catalyst [86][87] and even under solvent-free conditions [88]. More recently also metal complex-assisted or organocatalyzed hydrophosphinations have been reported. Several reviews focusing on hydrophosphination have been pusblished

• corresponding triflate under similar conditions [196][197]. The reaction also proceeded under solvent-free conditions with slightly higher yields [198]. A heterogeneous Pd/C catalyst has been applied as well [199][200]. The group of Glueck has reported the first asymmetric palladium-catalyzed C–P bond formation

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

• proved to be faster. However, a solvent-free approach also resulted in the desired β-lactams with similar results in yield, diastereoselectivity and time. Besides bicyclic systems, Ugi 4C-3CRs towards monocyclic β-lactams are also described in both organic and aqueous media. Pirrung et al. published a

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• recently, silver–NHC complexes were found to be valuable catalysts for this MCR. Their first application was reported by Wang and co-workers in 2008 [12], who developed a polystyrene-supported NHC–Ag(I) complex as an efficient catalyst for the A3-coupling under solvent-free conditions, at room temperature

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

• . Gratifyingly, yield and purity of pyrrole 7a increased when 6a was heated with microwaves to 250 °C under air cooling of the reaction vessel without any additive under solvent-free conditions. The results of the application of these conditions to cyanopyrrolines 6a–j are summarized in Table 1. This compound

Practical synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides via conventional and decarboxylative copper-free Sonogashira coupling reactions

• Andrea Caporale,
• Stefano Tartaggia,
• Andrea Castellin and
• Ottorino De Lucchi

Beilstein J. Org. Chem. 2014, 10, 384–393, doi:10.3762/bjoc.10.36

• variants have been introduced to perform efficiently this reaction with regard to synthetic and industrial aspects, including protocols in aqueous media [14][15][16][17], amine-free [18] or solvent-free conditions [19]. Moreover efficient reusable Pd catalysts [20][21][22][23][24] and even palladium-free

Silica: An efficient catalyst for one-pot regioselective synthesis of dithioethers

• Samir Kundu,
• Babli Roy and
• Basudeb Basu

Beilstein J. Org. Chem. 2014, 10, 26–33, doi:10.3762/bjoc.10.5

• Samir Kundu Babli Roy Basudeb Basu Department of Chemistry, North Bengal University, Darjeeling 734013, India, Fax: +91 353 2699001 10.3762/bjoc.10.5 Abstract The development of a silica-promoted highly selective synthesis of 1,2 or 1,3-dithioethers via solvent-free one-pot tandem reactions of an

• hydrothiolation of allylic substrates in a Markovnikov fashion to afford 1,2-dithioethers in one-pot reactions. In this paper, we wish to report our investigations on the reaction of allyl halides with excess thiols promoted by silica gel, which finally constitutes distinct protocols for one-pot, solvent-free

Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones – First evidence for the 1,3-oxathiole–thiocarbonyl ylide interconversion

• Valerij A. Nikolaev,
• Alexey V. Ivanov,
• Ludmila L. Rodina and
• Grzegorz Mlostoń

Beilstein J. Org. Chem. 2013, 9, 2751–2761, doi:10.3762/bjoc.9.309

• intensive red or orange color of thioketone 1. In order to enhance the concentration of the reagents and thereby increase the rate of the reaction, experiments with liquid diazocompounds 2a,c–e,h and i and thioketone 1a were carried out under solvent-free conditions. On the other hand, reactions of solid

Multigramme synthesis and asymmetric dihydroxylation of a 4-fluorobut-2E-enoate

• James A. B. Laurenson,
• John A. Parkinson,
• Jonathan M. Percy,
• Giuseppe Rinaudo and
• Ricard Roig

Beilstein J. Org. Chem. 2013, 9, 2660–2668, doi:10.3762/bjoc.9.301

• effective as the reaction solvent instead of carbon tetrachloride, allowing 23 and 24 to be isolated safely and reproducibly at scale (>300 mmol) in moderate yield (48–53%) after Kugelrohr distillation (Scheme 4). Fluorination was attempted using a range of conditions. The solvent-free reaction developed

Triol-promoted activation of C–F bonds: Amination of benzylic fluorides under highly concentrated conditions mediated by 1,1,1-tris(hydroxymethyl)propane

• Pier Alexandre Champagne,
• Alexandre Saint-Martin,
• Mélina Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2013, 9, 2451–2456, doi:10.3762/bjoc.9.283

• from our solvent-free conditions, which were providing the better results, we envisioned that further optimization was possible to improve the yield (Table 2). First, temperature had an important impact on conversion. Indeed, going from 60 °C (Table 2, entry 1) to 100 °C (Table 2, entry 3) smoothly

• neutral and solvent-free conditions. To further support this hypothesis, solvent properties concerning their hydrogen bond acidity or basicity correlate well with the experimental evidence of reactivity. Investigations concerning the reaction mechanism and precise role of the three hydroxy groups of 2 for

Silica sulfuric acid: a reusable solid catalyst for one pot synthesis of densely substituted pyrrole-fused isocoumarins under solvent-free conditions

• Sudipta Pathak,
• Kamalesh Debnath and
• Animesh Pramanik

Beilstein J. Org. Chem. 2013, 9, 2344–2353, doi:10.3762/bjoc.9.269

• pyrrole-fused isocoumarins, which employs solid-supported silica sulfuric acid (SSA) as catalyst, has been developed. When the mixture of ninhydrin adducts of acetylacetone/ethyl acetoacetate and primary amines was heated on the solid surface of SSA under solvent-free conditions, the pyrrole-fused

• isocoumarins were formed in good yields. This synthetic method has several advantages such as the employment of solvent-free reaction conditions without the use of any toxic reagents and metal catalysts, the ease of product isolation, the use of a recyclable catalyst, the low cost, the easy availability of the

• starting materials, and the excellent yields of products. Keywords: green chemistry; pyrrole-fused isocoumarin; reusable solid support; silica sulfuric acid; solvent-free condition; Introduction Isocoumarins are an important class of naturally occurring lactones [1][2][3], which has attracted the

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

• ; gold; gold catalysis; hydrophenoxylation; silver-free; single component; solvent-free; Introduction The use of gold compounds to promote hydroelementation reactions has grown tremendously over the past few years [1][2][3][4][5]. Using this approach, a host of different organic substrates have been

• is focused on the elimination of solvents and additives from the synthetic methodology [10]. Thus, the design of gold catalyzed reactions that proceed under solvent-free conditions and without the addition of silver salts or acidic promoters would be of interest to those charged with designing

• -free conditions [12][13]. To this end, we have synthesized and investigated a series of arylgold compounds as single-component catalysts for hydroelementation reactions under acid, silver, and solvent-free conditions. We recently reported the synthesis of arylgold compounds using a focused microwave

A³-Coupling catalyzed by robust Au nanoparticles covalently bonded to HS-functionalized cellulose nanocrystalline films

• Jian-Lin Huang,
• Derek G. Gray and
• Chao-Jun Li

Beilstein J. Org. Chem. 2013, 9, 1388–1396, doi:10.3762/bjoc.9.155

• reaches completion after 24 h under the present conditions. At a lower reaction temperature (25 °C), the Au@HS-CNC(4.4 mol %) showed lower conversion due to an incomplete reaction. We obtained the best conversion at a higher reaction temperature (above 80 °C). Solvent-free conditions proved to be the most

• nanoparticles at 80 °C, solvent-free in air. To expand the scope of this A3-coupling, we used various aldehydes and amines as substrates under the optimized reaction conditions, and the results are summarized in Table 2. Both aromatic and aliphatic aldehydes provided the desired products in good to moderate

• vacuum, and then reused with a fresh charge of reactants for a subsequent run of reactions under identical conditions. Figure 6 demonstrates that the catalyst could be used repetitively more than 11 times without significant deactivation, suggesting its good reusability in solvent-free A3-coupling of

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• hydroperoxide intermediate, prolonging the free-radical chain [39][40][41]. The NHPI-activation by AQ has been also adopted by other research groups. Li and co-workers applied the NHPI/AQ system to promote the metal and solvent-free oxidation of α-isophorone to ketoisophorone, preventing the isomerization