Formation of macrocyclic lactones in the Paternò–Büchi dimerization reaction

• Junya Arimura,
• Tsutomu Mizuta,
• Yoshikazu Hiraga and
• Manabu Abe

Beilstein J. Org. Chem. 2011, 7, 265–269, doi:10.3762/bjoc.7.35

• irradiated in degassed benzene with a high-pressure Hg lamp with a Pyrex filter (Scheme 3). Interestingly, the Paternò–Büchi dimer product 2a (R = Ph), which possesses Ci symmetry, was obtained as the major product and contains the biologically important macrocyclic lactone structure [30][31][32][33]. The

• Fisher Scientific LTD Orbitrap XL spectrometers, respectively, at the Natural Science Center for Basic Research and Development (N-BARD), Hiroshima University. The furan derivatives 1a–c (129 mg, 0.561 mmol) were dissolved in benzene (7.0 ml) and the degassed reaction mixture was irradiated with a high

• -pressure Hg lamp (300 W, hν > 290 nm) with a Pyrex filter. After 13 h, the solvent was removed in vacuo and dimethyl fumarate added as an internal standard. 1H NMR (500 MHz, CDCl3) was measured to determine the ratio of products. After the photoreaction, the residue was purified by repeated column

Heavy atom effects in the Paternò–Büchi reaction of pyrimidine derivatives with 4,4’-disubstituted benzophenones

• Feng-Feng Kong,
• Jian-Bo Wang and
• Qin-Hua Song

Beilstein J. Org. Chem. 2011, 7, 113–118, doi:10.3762/bjoc.7.16

• performed in acetonitrile-d3. A solution of the reactants was placed in a Pyrex NMR tube (transmitted light > 290 nm), purged with high purity N2 for 10 min and then irradiated with a 125 W high-pressure Hg lamp at 10 °C. The sample tubes were placed on a merry-go-round equipment moving around the Hg lamp

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• polymerization. Therefore it is difficult to know if the experiment represented a “true” miniemulsion polymerization process. A similar process was employed but with homogenization of catalyst/hexadecane/toluene, which was performed with either ultrasonication or high-pressure homogenizer in order to obtain a

Intramolecular hydroxycarbene C–H-insertion: The curious case of (o-methoxyphenyl)hydroxycarbene

• Dennis Gerbig,
• David Ley,
• Hans Peter Reisenauer and
• Peter R. Schreiner

Beilstein J. Org. Chem. 2010, 6, 1061–1069, doi:10.3762/bjoc.6.121

• maximum of 5 lies at 591 nm [21][22]. To rule out the existence of a persistent, non-tunneling carbene, irradiation experiments were conducted: Subsequent irradiation with a high-pressure Hg-lamp at λ = 577 nm, 546 nm, and 313 nm did not lead either to the appearance of new or the disappearance of

• approximately 50 mm. A high-pressure mercury lamp (HBO 200, Osram) with a monochromator (Bausch & Lomb) was used for irradiation. Experiments with deuterated acid were conducted accordingly. (o-Methoxyphenyl)glyoxylic acid (6) [25]. To a solution of 3.00 g (20.0 mmol) o-methoxyacetophenone in absolute pyridine

Functionalized copolyimide membranes for the separation of gaseous and liquid mixtures

• Nadine Schmeling,
• Roman Konietzny,
• Daniel Sieffert,
• Patrick Rölling and
• Claudia Staudt

Beilstein J. Org. Chem. 2010, 6, 789–800, doi:10.3762/bjoc.6.86

• of olefins/paraffins, e.g. propylene/propane, aromatic/aliphatic separation e.g. benzene/cyclohexane as well as high pressure gas separations, e.g. CO2/CH4 mixtures. In addition, opportunities for implementing the membrane units in conventional separation processes are discussed. Keywords: aromatics

• generally carried out if the quantity and quality are too low. Another very interesting application is the treatment of natural gas in offshore deposits. So far a huge number of gas resources are known worldwide, which cannot be exploited because of the high CO2 content and the high pressure of the mixture

• derivatives in current use. Conclusion It has been shown for the separation of high-pressure mixtures of CO2/CH4 as well as propylene/propane mixtures that the prepared cross-linked copolyimide membranes are much more plasticization resistant than non cross-linkable polyimide membranes used as reference

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective

• Norio Shibata,
• Andrej Matsnev and
• Dominique Cahard

Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65

• derivatives from −70 °C. Decomposition of the salts is rapid at –30 °C. However, reaction with O- and N-centered nucleophiles was possible with in situ generated trifluoromethyloxonium salts obtained by irradiation of 19 with a high-pressure mercury lamp at low temperature in dichloromethane; other

Synthesis, characterization and photoinduced curing of polysulfones with (meth)acrylate functionalities

• Cemil Dizman,
• Sahin Ates,
• Lokman Torun and
• Yusuf Yagci

Beilstein J. Org. Chem. 2010, 6, No. 56, doi:10.3762/bjoc.6.56

• instrument. Photocalorimetry (Photo-DSC) The photo-differential scanning calorimetry (Photo-DSC) measurements were carried out by means of a modified Perkin-Elmer Diamond DSC equipped with a high pressure mercury arc lamp (320–500 nm). A uniform UV light intensity was delivered across the DSC cell to the

Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions

• Gajanan M. Pawar,
• Jochen Weckesser,
• Siegfried Blechert and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2010, 6, No. 28, doi:10.3762/bjoc.6.28

• and λ2 = 343.600 nm, respectively. A 1000 ppm Rh standard (1N HNO3, Merck, Germany) was used to prepare standards of 0, 0.100, 1.00 and 10.00 ppm. General procedure for hydroformylation: The reaction was carried out in a 300 mL Parr high-pressure reactor. The reactor was evacuated, flushed with argon

Flow through reactors for organic chemistry: directly electrically heated tubular mini reactors as an enabling technology for organic synthesis

• Ulrich Kunz and
• Thomas Turek

Beilstein J. Org. Chem. 2009, 5, No. 70, doi:10.3762/bjoc.5.70

• well-controlled electromagnetic field generation. Cheap thermocouples cannot be used as sensors for temperature measurement and control. Temperature sensors cannot always be fixed directly into the reaction mixture because of limited chemical or mechanical stability. Operation under high pressure is

• [16]. The reactor outlet temperature was regulated taking a thermocouple (7) as a measure. This thermocouple is located in the middle of the liquid stream leaving the reactor. Thereby the temperature of the liquid is adjusted, not the wall temperature of the reactor. To allow operation at high

• pressure inside the tube the outlet was attached with a capillary to introduce a pressure drop. Conversion was measured with a detector (9) connected directly behind the capillary before the reactor outlet (8). All electric connections within the heater supply lines were made of 10 mm2 flexible insulated

Continuous flow based catch and release protocol for the synthesis of α-ketoesters

• Alessandro Palmieri,
• Steven V. Ley,
• Anastasios Polyzos,
• Mark Ladlow and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2009, 5, No. 23, doi:10.3762/bjoc.5.23

• products in high purity. Results and Discussion The experimental set up for these transformations involves the use of the Uniqsis FlowSyn™ device [55]. The fully integrated instrument employs a dual channel flow system, with each channel independently driven by a variable high-pressure piston pump. The

An expedient synthesis of 5-n-alkylresorcinols and novel 5-n-alkylresorcinol haptens

• Kirsti Parikka and
• Kristiina Wähälä

Beilstein J. Org. Chem. 2009, 5, No. 22, doi:10.3762/bjoc.5.22

• alkylphosphonium salts 4 in sealed vessels were not good due to degradation of the ylids under high pressure (ca. 9 bar). In contrast, reaction of the semi-stabilized benzylic ylid from 3 gave good yield under pressurized conditions, as well as in the open vessel (product 5, Table 1). A one-pot procedure was

Polyionic polymers – heterogeneous media for metal nanoparticles as catalyst in Suzuki–Miyaura and Heck–Mizoroki reactions under flow conditions

• Klaas Mennecke and
• Andreas Kirschning

Beilstein J. Org. Chem. 2009, 5, No. 21, doi:10.3762/bjoc.5.21

• high pressure/high temperature conditions aryl chlorides (for Suzuki–Miyaura reactions) or aryl bromides (for Heck–Mizoroki reactions) may very well serve as substrates for this kind of palladium species. Conclusion In summary, we demonstrated that polyionic gel 3 is a well suited ion exchange resin

Reversible intramolecular photocycloaddition of a bis(9-anthrylbutadienyl)paracyclophane – an inverse photochromic system. (Photoactive cyclophanes 5)

• Henning Hopf,
• Christian Beck,
• Jean-Pierre Desvergne,
• Henri Bouas-Laurent,
• Peter G. Jones and
• Ludger Ernst

Beilstein J. Org. Chem. 2009, 5, No. 20, doi:10.3762/bjoc.5.20

• , was irradiated at λ > 400 nm for 2 h with a high pressure mercury lamp in a Pyrex photoreactor. The cooling tube of the latter was filled with a NaNO2 solution (75 g/L) maintaining the reaction medium at 10–20 °C. After the end of irradiation, the solution was concentrated at ca 15 °C to 10 mL; then

Chemoselective reduction of aldehydes by ruthenium trichloride and resin- bound formates

• Basudeb Basu,
• Bablee Mandal,
• Sajal Das,
• Pralay Das and
• Ashis K. Nanda

Beilstein J. Org. Chem. 2008, 4, No. 53, doi:10.3762/bjoc.4.53

• alternative to hydrogenation using molecular hydrogen [1][2][3]. Since hydrogenation using molecular hydrogen is associated with risks and often requires high pressure apparatus, the alternative technique, CTH, has been employed in many laboratories. In transfer hydrogenation, several organic molecules such

Synthesis of (–)-Indolizidine 167B based on domino hydroformylation/cyclization reactions

• Giuditta Guazzelli,
• Raffaello Lazzaroni and
• Roberta Settambolo

Beilstein J. Org. Chem. 2008, 4, No. 2, doi:10.1186/1860-5397-4-2

• reaction mixture while the branched one 2b was in 13% (GC-MS control) with respect to the indolizine structure (Scheme 2). While at room temperature and high pressure the 2a/2b ratio is largely favorable to the branched aldehyde (29/71) [21], under the above conditions (high temperature and low pressure) a

• -tetrahydroindolizine 4 was obtained (Scheme 1; ii), together with the diastereoisomeric alcohols coming from the branched aldehyde: additional reduction of the pyrrole nucleus was never observed even by forcing the conditions (high pressure and high temperature). This goal was successfully reached by treating 4 (or 3

Photosonochemical catalytic ring opening of α-epoxyketones

• Hamid R. Memarian and
• Ali Saffar-Teluri

Beilstein J. Org. Chem. 2007, 3, No. 2, doi:10.1186/1860-5397-3-2

• were performed using a 400 W high pressure mercury lamp from Narva with cooling of samples in Duran glass. 1H NMR spectra of the mixture of photoproducts were measured in CDCl3 solutions containing tetramethylsilane (TMS) as internal standard on a Bruker drx-500 (500 MHz). Preparative layer