Synthesis and structures of ruthenium–NHC complexes and their catalysis in hydrogen transfer reaction

• Chao Chen,
• Chunxin Lu,
• Qing Zheng,
• Shengliang Ni,
• Min Zhang and
• Wanzhi Chen

Beilstein J. Org. Chem. 2015, 11, 1786–1795, doi:10.3762/bjoc.11.194

• [8][9][10][11][12][13][14][15][16] have been reported. In the family of metal complexes supported by functionalized NHCs, ruthenium complexes have long been a research focus on various applications such as catalysis and photochemistry [17][18][19][20][21][22][23][24][25][26]. However, the majority of

The chemical behavior of terminally tert-butylated polyolefins

• Dagmar Klein,
• Henning Hopf,
• Peter G. Jones,
• Ina Dix and
• Ralf Hänel

Beilstein J. Org. Chem. 2015, 11, 1246–1258, doi:10.3762/bjoc.11.139

• . Exploratory photochemical studies were carried out with tetraene 19 as the model compound. On irradiation this reacted with oxygen to the stable endo-peroxide 52. Keywords: bromination; Diels–Alder reactions; epoxidation; photochemistry; polyolefins; reactivity; hydrogenation; Introduction Several years ago

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

• reaction conditions are mandatory in order to succeed. The flow synthesis of the high profile antimalaria agent artemisinin (55) was reported by the Seeberger group in 2012 [61][62]. This intriguing approach represents one of the few examples where photochemistry has been employed in the synthesis of a

• also been employed in the flow synthesis of a carprofen analogue [69] as well as in the regioselective bromination towards a rosuvastatin precursor [70] showcasing how continuous flow photochemistry is receiving a significant level of interest. This is not least because of the perceived green reagent

• productivity. However, it should be noted that many of the articles promoting the use of flow photochemistry do not currently adequately quantify or describe the systems in sufficient detail in order to fully justify such statements [65]. This is a general consideration but especially pertinent to the use of

Probing multivalency in ligand–receptor-mediated adhesion of soft, biomimetic interfaces

• Stephan Schmidt,
• Hanqing Wang,
• Daniel Pussak,
• Simone Mosca and
• Laura Hartmann

Beilstein J. Org. Chem. 2015, 11, 720–729, doi:10.3762/bjoc.11.82

• . Intersection with the y-axis shows indicates the unspecific adhesion energies of unmodified SCPs (data not shown). PEG functionalization is based on radical benzophenone photochemistry and subsequent addition of carboxylic monomers (CA is depicted as an example). In the first step, benzophenone abstracts

Photocatalytic nucleophilic addition of alcohols to styrenes in Markovnikov and anti-Markovnikov orientation

• Martin Weiser,
• Sergej Hermann,
• Alexander Penner and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2015, 11, 568–575, doi:10.3762/bjoc.11.62

• different electron density. Representative mesoflow reactor experiments allowed to significantly shorten the irradiation times and to use sunlight as “green” light source. Keywords: electron transfer; perylene bisimide; photocatalysis; photochemistry; pyrene; Introduction Photocatalysts are organic or

Synthesis and surface grafting of a β-cyclodextrin dimer facilitating cooperative inclusion of 2,6-ANS

• Lars W. Städe,
• Thorbjørn T. Nielsen,
• Laurent Duroux,
• Reinhard Wimmer,
• Kyoko Shimizu and
• Kim L. Larsen

Beilstein J. Org. Chem. 2015, 11, 514–523, doi:10.3762/bjoc.11.58

• initial reports [1][2][3][4] of the cooperative effects exerted by β-cyclodextrin (β-CD) dimers, they have been suggested for a wide range of applications, for example, for catalysis [5][6] and photochemistry [7][8], as synthetic enzymes [5] and in general to obtain improved binding affinity (as compared

An integrated photocatalytic/enzymatic system for the reduction of CO₂ to methanol in bioglycerol–water

• Michele Aresta,
• Angela Dibenedetto,
• Tomasz Baran,
• Antonella Angelini,
• Przemysław Łabuz and
• Wojciech Macyk

Beilstein J. Org. Chem. 2014, 10, 2556–2565, doi:10.3762/bjoc.10.267

• . Keywords: CO2 chemistry; electron transfer; enzymatic CO2 reduction; NADH regeneration; photochemistry; photosensitization; Introduction The reduction of CO2 to fuel is a technology that could contribute to the recycling of large quantities of carbon. Among the various routes, the enzymatic reduction of

Molecular ordering at electrified interfaces: Template and potential effects

• Thanh Hai Phan and
• Klaus Wandelt

Beilstein J. Org. Chem. 2014, 10, 2243–2254, doi:10.3762/bjoc.10.233

• Thanh Hai Phan Klaus Wandelt Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany Laboratory of Photochemistry and Spectroscopy, Department of Chemistry, Catholic University of Leuven, Celestijnenlaan 200F, B-3001, Hevelee, Belgium Physics

Visible light photoredox-catalyzed deoxygenation of alcohols

• Daniel Rackl,
• Viktor Kais,
• Peter Kreitmeier and
• Oliver Reiser

Beilstein J. Org. Chem. 2014, 10, 2157–2165, doi:10.3762/bjoc.10.223

• developed is limited to benzylic, α-carbonyl, and α-cyanoalcohols; with other alcohols a slow partial C–F bond reduction in the 3,5-bis(trifluoromethyl)benzoate moiety occurs. Keywords: C–O bond activation; deoxygenation; photochemistry; photoredox catalysis; visible light; Introduction The dwindling

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

• Sanjeewa N. Senadheera,
• Abraham L. Yousef and
• Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

• rearrangement; photoremovable protecting groups; Introduction Phosphates have long held an important formative position in the development of organic photochemistry beginning with the seminal report by Havinga [1] of the unusual substituent effects in the photosolvolysis of aryl phosphates that showed

• reagents are required for protecting group release. Many photosolvolysis studies have targeted key biological substrates [6][8][9][10][11][12] for mechanistic and phenomenological studies. The culmination of these studies has resulted in the development of an entirely new branch of photochemistry with

• substrate. This limits the useful absorption range to ca. 350 to 400 nm for heterolysis by a primary photochemical pathway. Phosphates hold a central historic position in caged photochemistry through their cross-disciplinary significance in both biology and chemistry. Nucleotides (especially ATP, cAMP, and

Photo, thermal and chemical degradation of riboflavin

• Muhammad Ali Sheraz,
• Sadia Hafeez Kazi,
• Sofia Ahmed,
• Zubair Anwar and
• Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

• slightly different photochemistry was observed which does not involve any primary photoreduction in the solvents. The major photodegradation products formed in alcohols were LC and FMF [83]. LC has also been identified as the major photoproduct of RF in various organic solvents such as acetic acid, acetone

Visible-light photoredox catalyzed synthesis of pyrroloisoquinolines via organocatalytic oxidation/[3 + 2] cycloaddition/oxidative aromatization reaction cascade with Rose Bengal

• Carlos Vila,
• Jonathan Lau and
• Magnus Rueping

Beilstein J. Org. Chem. 2014, 10, 1233–1238, doi:10.3762/bjoc.10.122

• /oxidative aromatization cascade using Rose Bengal as an organo-photocatalyst. A variety of pyrroloisoquinolines have been obtained in good yields under mild and metal-free reaction conditions. Keywords: alkaloids; [3 + 2] cycloaddition; organocatalysis; oxidation; photochemistry; photoredox catalysis; Rose

Tailoring of organic dyes with oxidoreductive compounds to obtain photocyclic radical generator systems exhibiting photocatalytic behavior

• Christian Ley,
• Julien Christmann,
• Ahmad Ibrahim,
• Luciano H. Di Stefano and
• Xavier Allonas

Beilstein J. Org. Chem. 2014, 10, 936–947, doi:10.3762/bjoc.10.92

• Christian Ley Julien Christmann Ahmad Ibrahim Luciano H. Di Stefano Xavier Allonas Laboratory of Macromolecular Photochemistry and Engineering, University of Haute Alsace, 3b rue Alfred Werner, 68093 Mulhouse, France 10.3762/bjoc.10.92 Abstract The combination of a dye which absorbs the photon

• transfer; kinetic; photocatalysis; photochemistry; photocyclic initiating system; photopolymerization; photoredox catalysis; radical generator; Introduction Among the possible usage of light, the conversion of photons into chemical energy, as stored into radicals or ions, is of great interest. As a part

Visible-light-induced, Ir-catalyzed reactions of N-methyl-N-((trimethylsilyl)methyl)aniline with cyclic α,β-unsaturated carbonyl compounds

• Dominik Lenhart and
• Thorsten Bach

Beilstein J. Org. Chem. 2014, 10, 890–896, doi:10.3762/bjoc.10.86

• lactone and lactam substrates, the latter products were the only products isolated. For the six-membered lactones and lactams and for cyclopentenone the simple addition products prevailed. Keywords: cyclization; electron transfer; iridium; photochemistry; photoredox catalysis; radical reactions

Metal and metal-free photocatalysts: mechanistic approach and application as photoinitiators of photopolymerization

• Jacques Lalevée,
• Sofia Telitel,
• Pu Xiao,
• Marc Lepeltier,
• Frédéric Dumur,
• Fabrice Morlet-Savary,
• Didier Gigmes and
• Jean-Pierre Fouassier

Beilstein J. Org. Chem. 2014, 10, 863–876, doi:10.3762/bjoc.10.83

• introduced into the polymer photochemistry field (area) in the very past years (see a review in [15][16][17][18][19][20][21][22]). Indeed, in this area, free-radical photopolymerization (FRP, Scheme 1, reactions 1 and 2), cationic photopolymerization (CP, Scheme 1, reactions 3 and 4), free-radical promoted

A combined continuous microflow photochemistry and asymmetric organocatalysis approach for the enantioselective synthesis of tetrahydroquinolines

• Erli Sugiono and
• Magnus Rueping

Beilstein J. Org. Chem. 2013, 9, 2457–2462, doi:10.3762/bjoc.9.284

• the synthesis of tetrahydroquinolines from readily available 2-aminochalcones using a combination of photochemistry and asymmetric Brønsted acid catalysis. The photocylization and subsequent reduction was performed with catalytic amount of chiral BINOL derived phosphoric acid diester and Hantzsch

• dihydropyridine as hydrogen source providing the desired products in good yields and with excellent enantioselectivities. Keywords: asymmetric transfer hydrogenation; binolphosphate; continuous-flow reactors; flow chemistry; microreactors; organocatalysis; photochemistry; Introduction Tetrahydroquinolines [1][2

• have been adopted for photochemical applications and microflow photochemistry has emerged as efficient synthesis tool [23][24][25][26][27][28][29][30][31]. The narrow inner dimensions of microfabricated reactors is advantageous for photochemical synthesis since it allows better light penetration and

Synthesis of homo- and heteromultivalent carbohydrate-functionalized oligo(amidoamines) using novel glyco-building blocks

• Felix Wojcik,
• Sinaida Lel,
• Alexander G. O’Brien,
• Peter H. Seeberger and
• Laura Hartmann

Beilstein J. Org. Chem. 2013, 9, 2395–2403, doi:10.3762/bjoc.9.276

• heteromultivalent glycosylation patterns by combining building blocks presenting different mono- and disaccharides. Keywords: continuous flow; flow chemistry: flow synthesis; glycoligands; multivalency; photochemistry; solid-phase synthesis; thiol–ene; thioglycosides; Introduction Multivalent carbohydrate ligand

Microflow photochemistry: UVC-induced [2 + 2]-photoadditions to furanone in a microcapillary reactor

• Sylvestre Bachollet,
• Kimitada Terao,
• Shin Aida,
• Yasuhiro Nishiyama,
• Kiyomi Kakiuchi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2013, 9, 2015–2021, doi:10.3762/bjoc.9.237

• chemistry; furanone; microflow chemistry; photochemistry; Introduction Continuous-flow chemistry has recently emerged as a new methodology in organic chemistry [1][2][3][4]. The combination of microstructured dimensions and flow operations has also proven advantageous for photochemical applications [5][6

• test tube. The microcapillary unit had a 9-times larger surface-to-volume ratio, which resulted in a more efficient harvest of the available light. The results contribute to the growing field of ‘microflow photochemistry’ [5][6][7][8][9] and ‘green flow chemistry’ [42][43][44][45]. It is hoped that

• this technology will help to overcome the current reservations towards synthetic organic photochemistry [46] and that it will find future applications in chemical and pharmaceutical processes [47][48]. Experimental General All commercially available starting materials and reagents were purchased from

The chemistry of amine radical cations produced by visible light photoredox catalysis

• Jie Hu,
• Jiang Wang,
• Theresa H. Nguyen and
• Nan Zheng

Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234

• oxidants [12][13][14], metal-catalyzed oxidation [15][16][17][18], UV light-mediated photochemistry [7][19][20][21], and visible light-mediated photochemistry [22][23]. Recently, the last approach has become a major research focus in organic chemistry. The enthusiasm surrounding this approach is partially

Topochemical control of the photodimerization of aromatic compounds by γ-cyclodextrin thioethers in aqueous solution

• Hai Ming Wang and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1858–1866, doi:10.3762/bjoc.9.217

• complexes with polycyclic aromatics, such as naphthalene, anthracene (ANT), and acenaphthylene (ACE) [25]. In the following we report on the photochemistry of ANT, ACE and coumarin (COU), templated by complexation in several hydrophilic γ-CD thioethers 1–7 (Figure 1 and Figure 2). Special attention will be

• paid to both the quantum yields Φ and stereoselectivities of the photodimerizations. Results and Discussion Photodimerization of anthracene Due to the fact that the inclusion compounds of ANT in native β-CD or γ-CD are completely insoluble in water, only the aqueous photochemistry of hydrophilic ANT

• also favors the formation of the anti dimer. (c) The anti dimer appears to better fit into the γ-CD cavity than the syn isomer, as depicted in Figure 4. Stereoselective photodimerization of coumarin The photochemistry of COU and its derivatives is rather complex because the quantum yield and

[3 + 2]-Cycloadditions of nitrile ylides after photoactivation of vinyl azides under flow conditions

• Stephan Cludius-Brandt,
• Lukas Kupracz and
• Andreas Kirschning

Beilstein J. Org. Chem. 2013, 9, 1745–1750, doi:10.3762/bjoc.9.201

• from the corresponding vinyl azide. Keywords: azirines; cycloaddition; flow chemistry; flow reactors; inductive heating; nitrile ylides; photochemistry; vinyl azides; Introduction Recently, photochemistry has seen a renaissance despite the fact that under batch conditions specialized reaction vessels

• are required, in which the light source is placed in the centre of the reaction mixture: Technically this setup is difficult to control for large scale industrial applications because the issue of transferring a substantial amount of heat has to be addressed. On the other hand, photochemistry allows

• -chemistry laboratories, photochemistry has found a wider interest in the chemical community [17][18]. Particularly large-scale photochemical syntheses can simply be achieved by numbering-up miniaturized flow reactors in a parallel set-up. Uniform irradiation can be guaranteed when the penetration depth of

Thermochemistry and photochemistry of spiroketals derived from indan-2-one: Stepwise processes versus coarctate fragmentations

• Götz Bucher,
• Gernot Heitmann and
• Rainer Herges

Beilstein J. Org. Chem. 2013, 9, 1668–1676, doi:10.3762/bjoc.9.191

• ) should be thermochemically activated (Scheme 2) [22]. To test the above hypothesis, we now investigate the thermochemistry and the photochemistry of the ketals 1 and 3, derived from indan-2-one and ethylene glycol, and cis-2-butene-1,4-diol (Scheme 3). The ketal 2, derived from 1,3-propanediol, was

• :1. It is noted, however, that the formation of CO may well be due to photolysis of CO2 due to hard UV radiation (λ = 185 nm) also emitted by the Hg low-pressure lamp used [24]. In contrast to the very clean photochemistry of 1, flash vacuum pyrolysis FVP (T = 870 °C) of 1, followed by trapping of

• . Relative to [CO2] = 1.0, the concentrations of the other pyrolysis products are as follows: [CO] = 27.2, [IN] = 3.8, [ET] = 15.9, [BC] = 11.4, [XY] = 1.3, [AA] = 3.9 [25]. Formaldehyde is formed as a minor product only. The photochemistry of ketals 2 and 3 was investigated as well by matrix isolation

Organotellurium-mediated living radical polymerization under photoirradiation by a low-intensity light-emitting diode

• Yasuyuki Nakamura and
• Shigeru Yamago

Beilstein J. Org. Chem. 2013, 9, 1607–1612, doi:10.3762/bjoc.9.183

• been widely employed in conventional radical polymerization for various applications such as coatings, adhesives, gels and microelectronics [4][5][6][7]. The major motivation for the utilization of photochemistry in LRP is that it enables the dormant species to be activated under mild thermal

Electron self-exchange activation parameters of diethyl sulfide and tetrahydrothiophene

• Martin Goez and
• Martin Vogtherr

Beilstein J. Org. Chem. 2013, 9, 1448–1454, doi:10.3762/bjoc.9.164

• solvent reorganization. Keywords: CIDNP; electron transfer; free radicals; kinetics; photochemistry; pyrylium salts; self-exchange; sulfides; Introduction Single-electron transfer is probably the simplest chemical process of an organic molecule, because usually no full bonds are broken or formed. For

New core-pyrene π structure organophotocatalysts usable as highly efficient photoinitiators

• Sofia Telitel,
• Frédéric Dumur,
• Thomas Faury,
• Bernadette Graff,
• Mohamad-Ali Tehfe,
• Didier Gigmes,
• Jean-Pierre Fouassier and
• Jacques Lalevée

Beilstein J. Org. Chem. 2013, 9, 877–890, doi:10.3762/bjoc.9.101

• ; photocatalysts; photoinitiators; radical photopolymerization; Introduction Free radical sources are encountered in various areas such as organic chemistry, biochemistry and polymer chemistry. In the field of polymer photochemistry applied to photopolymerization reactions, they are referred to as photoinitiators