Visible-light photoredox catalysis enabled bromination of phenols and alkenes

• Yating Zhao,
• Zhe Li,
• Chao Yang,
• Run Lin and
• Wujiong Xia

Beilstein J. Org. Chem. 2014, 10, 622–627, doi:10.3762/bjoc.10.53

• the optimized conditions in hand, we prepared a variety of phenols which were subjected to the photocatalytic reaction. In general, both electron-withdrawing and electron–donating groups were tolerated as substituents R2 in this process. Interestingly, the substrates protected with TMS (trimethylsilyl

• cyclohexane-1,3-dione (5) and (E)-4-(4-methoxyphenyl)but-3-en-1-ol (7) under the same reaction conditions led to 2,2-dibromocyclohexane-1,3-dione (6) and bromofuran compound 8 in 22% and 52% yield, respectively (Scheme 4). This outcome demonstrates the efficiency of the Ru(bpy)3Cl2/CBr4 photocatalytic system

• situ generation of bromine. Synthesis of dibromophenol product 2b''. Scope of the photocatalytic bromination of alkenes. Bromination of diketones and cyclization reactions. Survey of the photocatalytic bromination reaction conditions. Scope of the photocatalytic bromination of phenols. Supporting

Synthesis, characterization and initial evaluation of 5-nitro-1-(trifluoromethyl)-3H-1λ³,2-benziodaoxol-3-one

• Nico Santschi,
• Roman C. Sarott,
• Elisabeth Otth,
• Reinhard Kissner and
• Antonio Togni

Beilstein J. Org. Chem. 2014, 10, 1–6, doi:10.3762/bjoc.10.1

• directed towards the photocatalytic one-electron reduction of these compounds in order to generate the highly electrophilic trifluoromethyl radical [5][6][7]. For example, Gouverneur et al. have highlighted the regioselective allylic trifluoromethylation employing reagent 2, [Ru(bpy)3]Cl2 and allylsilanes

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

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

• approach work, several hurdles need to be addressed. First, a labile carbon–metal bond is desired in order to have an efficient turnover of the metal. Second, the metal complex needs to be compatible with the strongly reducing intermediates (e.g., superoxide) produced in the photocatalytic cycle. Third

• and indoles are then added to the N-acyliminium ions 68b to provide the amidoalkylation products 69. Alternatively, the use of only persulfate at 55 °C afforded the same products. However, higher yields and better selectivities were generally observed with the photocatalytic process. Intercepted by

[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

• to perform many transformations that are hardly possible under thermal conditions. This includes photocatalytic reactions that have seen an immense interest lately [1]. Nitrile ylides 3 are 1,3-dipoles that have served for the preparation of different five-membered N-heterocycles in 1,3-dipolar

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

• the photocatalytic oxidative activation of NHPI by graphitic carbon nitride (g-C3N4) and visible light irradiation [65]. g-C3N4, the most stable allotrope of carbon nitride, is a two-dimensional polymer with a tri-s-triazine ring unit and a π-conjugated layered structure similar to graphene. It is a

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

• both Rp and conv are better when comparing to Py_3/MDEA. Photocatalyst behavior of the Co_Pys The photocatalytic behavior of the Co_Pys is investigated in the most interesting compounds reported above for the photopolymerization reactions. The steady-state photolysis of Py_3/PBr, Py_3/Iod, Py_3/MDEA

• , we have demonstrated the true occurrence of a unique oxidation cycle). Conclusion In this paper, the core-pyrene π structures Co_Pys appear as interesting photoinitiators. Successful cationic and radical photopolymerization reactions were carried out under near-UV–vis irradiation. A photocatalytic

Spectroscopic characterization of photoaccumulated radical anions: a litmus test to evaluate the efficiency of photoinduced electron transfer (PET) processes

• Maurizio Fagnoni,
• Stefano Protti,
• Davide Ravelli and
• Angelo Albini

Beilstein J. Org. Chem. 2013, 9, 800–808, doi:10.3762/bjoc.9.91

• aromatic compounds known to participate in photosubstitution or photocatalytic alkylation reactions. It was proposed to ascertain whether these may accumulate, as often observed in electrochemistry [33][34] and by pulse radiolysis [35], but rarely in photochemistry. Results The acceptors chosen for this

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

• nanoparticles can effectively produce singlet oxygen when irradiated with LEDs in the oxidative degradation of 1,3-diphenylisobenzofuran [40]. Photocatalytic reactions Photocatalytic reactions are an area in which continuous flow can be particularly advantageous due to the large surface-to-volume ratio ensuring

• , thus, gave data ideally suited to mechanistic studies [56]. The potential of microreactors in the photocatalytic splitting of water has also come under investigation. In this case a rhodium-containing inorganic photocatalyst was employed, and again online QMS permitted mechanistic studies to be

Photochemistry with laser radiation in condensed phase using miniaturized photoreactors

• Elke Bremus-Köbberling,
• Arnold Gillner,
• Frank Avemaria,
• Céline Réthoré and
• Stefan Bräse

Beilstein J. Org. Chem. 2012, 8, 1213–1218, doi:10.3762/bjoc.8.135

• combinatorial flow chemistry in lab-on-a-chip applications. Photochemical processes are in this case particularly interesting because of their enhanced molecular activation [8]. Photochemistry in microreactors is an emerging research area [9], and especially photocatalytic reactions have been investigated in

Synthesis of new pyrrole–pyridine-based ligands using an in situ Suzuki coupling method

• Matthias Böttger,
• Björn Wiegmann,
• Steffen Schaumburg,
• Peter G. Jones,
• Wolfgang Kowalsky and
• Hans-Hermann Johannes

Beilstein J. Org. Chem. 2012, 8, 1037–1047, doi:10.3762/bjoc.8.116

• nine and thereby saturated. Our interest in this type of complex is driven by its potential analytical application for luminescence degradation measurements on photocatalytic surfaces [8]. Currently, β-diketonate complexes are in use for this analysis, but homoleptic complexes may be advantageous in

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

• catalytic efficacy, flavin derivatives bearing a guanidinium ion as oxoanion binding site were prepared. Chromophore and substrate binding site are linked by a rigid Kemp’s acid structure. The molecular structure of the new flavins was confirmed by an X-ray structure analysis and their photocatalytic

• 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

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

• carbonyl compounds [43][44][45][46][47][48][49][50] or by nucleophilic attack of appropriate reagents. [36][39][51] Recently, we have reported on the photocatalytic ring opening of α-epoxyketones 1a-f and 2,4,6-triphenylpyrilium tetrafluoroborate (TPT) as photocatalyst in methanol, [37] cyclohexanone, [38

• simultaneous irradiation of ultrasound and UV-light for catalytic ring opening of α-epoxyketones 1a-f in the presence of this photocatalyst in methanol. The main goal of the present work was to elucidate the effect of both irradiation sources separately or together on the rate of photocatalytic ring opening of

• of photocatalytic ring opening of α-epoxyketones 1b, 1d and 1f, the same substituents on the phenyl ring of the benzoyl group (1c and 1e) have a smaller effect. In the cases of 1b and 1d, the ratios of the diastereomeric photoproducts are inversed. We have proposed the involvement of three different