One-pot functionalisation of N-substituted tetrahydroisoquinolines by photooxidation and tunable organometallic trapping of iminium intermediates

• Joshua P. Barham,
• Matthew P. John and
• John A. Murphy

Beilstein J. Org. Chem. 2014, 10, 2981–2988, doi:10.3762/bjoc.10.316

• ). Alternatively, the α-amino radicals can be trapped by electrophiles [7][8][9]. Oxidative C–H functionalisation of THIQs is reported using Cu(I) [10][11], Fe(III) [12], V(IV) [13] and I2 [14][15] catalysts, but also with heterogeneous [16], metal-organic [17][18] and organic [19][20] photocatalysts. Such

• tertiary amine substrates and unstabilised carbon nucleophiles. Recently, visible-light photoredox catalysis has gained interest as a technique for oxidative functionalisation [34][35]. An important feature of photoredox catalysis is that different photocatalysts have different redox potentials upon

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

• . For the approach discussed here, the production of one mol of CH3OH from CO2 requires three enzymes and the consumption of three mol of NADH. Regeneration of the cofactor NADH from NAD+ was achieved by using visible-light-active, heterogeneous, TiO2-based photocatalysts. The efficiency of the

• H2O splitting have received significant interest due to their potential environmental and resource preservation benefits [12][13]. Interestingly, the oxidized forms of some common waste organics may find practical application. The use of heterogeneous photocatalysts in the process of NADH regeneration

• ]. Additionally, the properties of other photocatalysts (Cu2O, InVO4, and TiO2, which are less active than the Cr-modified TiO2 photocatalysts), which were modified with the organic compound “rutin”, are briefly presented. Figure 2 shows the transformed diffuse reflectance spectra of the photocatalysts converted

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

• substitution pattern of benzoates we intended to shift the electrochemical reduction potentials of the substances into a region that could be accessed by common visible light photocatalysts. The substituents should be as inert as possible in order not to interfere with the photochemical reaction itself

• ; dtb-bpy = 4,4′-di-tert-butyl-2,2′-bipyridine] as photocatalysts, Hantzsch ester (diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate) as hydrogen donor, and iPr2NEt as sacrificial electron donor in DMF (Scheme 3). Light generated from a high power LED was channeled into the reaction solution in

• monobenzoate 6e. Reduction of benzoate moiety in case of non-benzylic alcohols. Optimized conditions for larger scale applications. Comparison of different esters and photocatalysts in deoxygenation reaction. Solvent/temperature dependence and control experiments of deoxygenation reaction with 3,5-bis

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

• recently Zhao reported the same reaction using C60-Bodipy hybrids [30] and porous material immobilized iodo-Bodipy [31] as photocatalysts, obtaining in both cases good yields for different pyrrolo[2,1-a]isoquinolines. Finally, Lu presented in 2013 a dirhodium complex for the synthesis of these compounds

Organic synthesis using photoredox catalysis

• Axel G. Griesbeck

Beilstein J. Org. Chem. 2014, 10, 1097–1098, doi:10.3762/bjoc.10.107

• synthesis, the principles of photoredox chemistry serve as guidelines, i.e., photoinduced electron transfer (PET) kinetics and thermodynamics as expressed in the Rehm–Weller and Marcus equations. For catalytic versions, the photoinduced redox processes require efficient and robust photocatalysts, and in

On the mechanism of photocatalytic reactions with eosin Y

• Michal Majek,
• Fabiana Filace and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2014, 10, 981–989, doi:10.3762/bjoc.10.97

• photocatalysts [3][4][5][6][7][8], whereas much less attention has been directed at eosin Y-catalyzed reactions. The reductive quenching pathway of eosin Y, which operates in the photooxidation of isoquinolines [9], has been studied in a single report [22]. To the best of our knowledge, related data have not

• -driven reactions that lie beyond the focus of this study. Eosin Y (and many other organic photocatalysts) undergo rapid acid–base equilibria which significantly alter the photophysical properties. It is therefore of pivotal importance to ascertain the actual nature of the employed dye under the reaction

Visible light mediated intermolecular [3 + 2] annulation of cyclopropylanilines with alkynes

• Theresa H. Nguyen,
• Soumitra Maity and
• Nan Zheng

Beilstein J. Org. Chem. 2014, 10, 975–980, doi:10.3762/bjoc.10.96

• compounds [21][22][23][24][25][26]. Amines have been used as an electron donor to reduce the excited state of photocatalysts, while they are oxidized to amine radical cations. Our group and others have taken advantage of this facile redox process and developed a number of synthetic methods that harness the

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

• formerly: University of Haute Alsace/ENSCMu, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France 10.3762/bjoc.10.83 Abstract In the present paper, the photoredox catalysis is presented as a unique approach in the field of photoinitiators of polymerization. The principal photocatalysts already reported as

• well as the typical oxidation and reduction agents used in both reductive or oxidative cycles are gathered. The chemical mechanisms associated with various systems are also given. As compared to classical iridium-based photocatalysts which are mainly active upon blue light irradiation, a new

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

• ). Therefore, a photocatalyst is often required to initialize electron-transfer reactions with amines. Some of the frequently used photocatalysts include ruthenium [24][25][26] and iridium [27][28] polypyridyl complexes as well as organic dyes [29][30] that are absorbed in the visible-light region. They all

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. Successful results in terms of rates of polymerization and final conversions were obtained. The strong MO coupling between the six different cores and the pyrene moiety was studied by DFT calculations. The different chemical intermediates are characterized by ESR and laser flash photolysis

• ; 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

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• been shown to be unsuccessful under batch conditions. Nevertheless, the low flow rates and low concentrations involved limited output to 2.4 µmol/h, leaving significant questions over its synthetic utility [48][49][50]. Other redox chemistry to be performed by using titanium dioxide photocatalysts

Microphotochemistry: 4,4'-Dimethoxybenzophenone mediated photodecarboxylation reactions involving phthalimides

• Oksana Shvydkiv,
• Kieran Nolan and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2011, 7, 1055–1063, doi:10.3762/bjoc.7.121

• light, its removal from the product remains challenging. Compared to their acetone-sensitized counterparts [27], however, selectivities and yields were reduced. We are therefore currently investigating water soluble or solid-supported photocatalysts that absorb in the UVA region. The results from this

Synthesis of rigidified flavin–guanidinium ion conjugates and investigation of their photocatalytic properties

• Harald Schmaderer,
• Mouchumi Bhuyan and
• Burkhard König

Beilstein J. Org. Chem. 2009, 5, No. 26, doi:10.3762/bjoc.5.26

• bonding site for oxoanions or carbonyl groups [45][46][47][48][49]. The structure of the new flavins was determined in solid state and in solution and their photocatalytic properties were tested. Results and Discussion Synthesis The synthesis of the potential photocatalysts 1 and 2, consisting of the

• bonds [54][55][56][57][58] and in solution the flavin chromophore is expected to rotate freely around the C–C single bonds of the ethane linker. Photocatalytic reactions Compounds 1 and 2 were tested as photocatalysts in three different reactions and their performance was compared to tetraacetyl

• effectively transferred in 1 and 2 to the relative flavin–guanidinium ion orientation, which is due to the flexible ethane linker between imide and flavin. Derivatives with a more constrained conformation of the flavin chromophore and the substrate binding sites may lead to chemical photocatalysts with better