Photoredox-catalyzed silyldifluoromethylation of silyl enol ethers

• Vyacheslav I. Supranovich,
• Vitalij V. Levin and
• Alexander D. Dilman

Beilstein J. Org. Chem. 2020, 16, 1550–1553, doi:10.3762/bjoc.16.126

• analyzed by 19F NMR spectroscopy. A series of typical photocatalysts (for example, iridium catalysts) were ineffective in promoting the reaction. Rewardingly, a gold catalyst, [AuCl(μ-dppm)]2 [25][26][27], provided reasonable yields of 3a after one day of irradiation along with a full conversion of the

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• growth resides in the availability of visible light-absorbing transition metal complexes. These catalysts can harvest the energy of visible-light photons and transfer it to organic molecules, giving access to key reactive intermediates. For instance, ruthenium and iridium polypyridyl complexes played a

Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties

• Nuray Altinolcek,
• Ahmet Battal,
• Mustafa Tavasli,
• William J. Peveler,
• Holly A. Yu and
• Peter J. Skabara

Beilstein J. Org. Chem. 2020, 16, 1066–1074, doi:10.3762/bjoc.16.93

• themselves or in combination with iridium, are also used as emissive materials in OLEDs [8]. In this respect a molecule bearing a dithienylbenzothiadiazole unit and four alkyl-linked peripheral carbazole groups (named as TCTzC) is used in the construction of saturated red emissive OLEDs [9]. Carbazole-based

• homoleptic or heteroleptic iridium(III) complexes were also reported in the construction of different OLEDs [10][11][12][13]. In OPVs, carbazole derivatives are frequently used as small molecule p-type (electron-donating) materials or electron-accepting (n-type) materials with a variety of donor–acceptor

Photocatalytic deaminative benzylation and alkylation of tetrahydroisoquinolines with N-alkylpyrydinium salts

• David Schönbauer,
• Carlo Sambiagio,
• Timothy Noël and
• Michael Schnürch

Beilstein J. Org. Chem. 2020, 16, 809–817, doi:10.3762/bjoc.16.74

• borylations [41][42], heteroarylations [43], and thioesterifications [44]. Additionally, several methods using photoredox chemistry were also published. For instance, the alkylation of isoquinolines under iridium catalysis and alkynylation with eosin Y as the catalyst [45][46]. In this contribution, we

• demonstrate the deaminative coupling of N-benzylpyridinium Katritzky salts with THIQs under ruthenium photoredox catalysis. During the preparation of this article, a similar transformation was disclosed using an iridium photoredox catalyst [47]. Results and Discussion We started our investigations by

• ). Eosin Y was inefficient under these conditions (Table 1, entry 20). Since [Ru(bpy)3]Cl2 is significantly cheaper than the iridium catalyst, the former was used in further reactions. Regarding the addition of different bases, the yield remained unchanged, when lutidine was added. Potassium carbonate and

One-pot synthesis of dicyclopenta-fused peropyrene via a fourfold alkyne annulation

• Ji Ma,
• Yubin Fu,
• Junzhi Liu and
• Xinliang Feng

Beilstein J. Org. Chem. 2020, 16, 791–797, doi:10.3762/bjoc.16.72

• and Discussion The synthesis of compound 1 is depicted in Scheme 2. Firstly, 2,7-bis(Bpin)pyrene (3) was prepared using an iridium-catalyzed borylation of pyrene (67% yield). Then, 2,7-diphenylpyrene (4) was obtained by Suzuki cross-coupling of 3 and bromobenzene in 77% yield. After that, the

Direct borylation of terrylene and quaterrylene

• Haruka Kano,
• Keiji Uehara,
• Kyohei Matsuo,
• Hironobu Hayashi,
• Hiroko Yamada and
• Naoki Aratani

Beilstein J. Org. Chem. 2020, 16, 621–627, doi:10.3762/bjoc.16.58

• solubilizing groups along the rylene backbone, and all the substituents of the terrylenes and quaterrylenes were introduced before creating the rylene skeleton. In this work, we successfully synthesized 2,5,10,13-tetrakis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)terrylene (TB4) by using an iridium-catalyzed

• quite limited because they must suffer the harsh conditions of the rylene skeleton preparation. Basic reactivity of rylenes with electrophiles is predicted from perylene in which the most reactive sites are the 3,4,9,10-positions [21]. On the other hand, the regioselectivity of the iridium (Ir

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• organic chemistry. Despite the impressive advances reported since the renewal of the field in 2008 [2][3][4], several issues still have to be addressed. Indeed, most of the developed reactions relied on the use of organometallic complexes of expensive noble metals, such as iridium and ruthenium [5]. Even

Six-fold C–H borylation of hexa-peri-hexabenzocoronene

• Mai Nagase,
• Kenta Kato,
• Akiko Yagi,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2020, 16, 391–397, doi:10.3762/bjoc.16.37

• , Nagoya, 464-8602, Japan 10.3762/bjoc.16.37 Abstract Hexa-peri-hexabenzocoronene (HBC) is known to be a poorly soluble polycyclic aromatic hydrocarbon for which direct functionalization methods have been very limited. Herein, the synthesis of hexaborylated HBC from unsubstituted HBC is described. Iridium

• calculations. The spectra revealed a bathochromic shift of absorption bands compared with unsubstituted HBC under the effect of the σ-donation of boryl groups. Keywords: C–H borylation; hexa-peri-hexabenzocoronene; iridium catalyst; X-ray crystallography; Introduction Polycyclic aromatic hydrocarbons (PAHs

• borylation of unsubstituted HBC. HBC was pulverized by a ball mill prior to use. First, we attempted the iridium catalyst and reagents that we have reported as the suitable C–H borylation conditions for warped nanographene: [Ir(OMe)cod]2, 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen), HBpin (Bpin: 4,4,5,5

Synthesis and optoelectronic properties of benzoquinone-based donor–acceptor compounds

• Daniel R. Sutherland,
• Nidhi Sharma,
• Georgina M. Rosair,
• Ifor D. W. Samuel,
• Ai-Lan Lee and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2019, 15, 2914–2921, doi:10.3762/bjoc.15.285

• noble metal complex, such as those based on iridium(III) [22]; (2) triplet–triplet annihilation (TTA) [23], or (3) TADF. The maximum IQE for TTA is 62.5%, whereas for TADF, it is as high as 100% [24]. TADF emitter development has thus emerged as an effective avenue to achieve high performance in OLEDs

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• conditions as for the 1H-pyridine from alkynone 3a was conducted, but only starting material could be isolated. Another option for the formation of the 1H-pyridine 5a was envisioned by an in situ generation of a dimer of ethyl cyanoacetate (4). The dimer 7 can be synthesized by iridium catalysis [30]. With

Photochromic diarylethene ligands featuring 2-(imidazol-2-yl)pyridine coordination site and their iron(II) complexes

• Andrey G. Lvov,
• Max Mörtel,
• Anton V. Yadykov,
• Frank W. Heinemann,
• Valerii Z. Shirinian and
• Marat M. Khusniyarov

Beilstein J. Org. Chem. 2019, 15, 2428–2437, doi:10.3762/bjoc.15.235

• their complexes with rhodium(I) [18], platinum(II) [30], and iridium(III) [31] were reported. In contrast, in our work, the 2-(imidazol-2-yl)pyridine unit is used as a heterocyclic moiety of diarylethenes with cyclopentenone, cyclopentene, and cyclohexenone ethene bridges. The novel ligands have been

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• Scheme 45a. Cyclooctadiene iridium chloride dimer, [IrCl(COD)]2, was an effective catalyst to promote this fluorination with Et3N·3HF, forming allylic fluorides in moderate to good yields. This facile method shows a good regioselectivity to gain the branched isomer within 1 h. Later in 2017, they

• described a similar method for the asymmetric fluorination of racemic allylic trichloroacetimidates utilizing a chiral bicyclo[3.3.0]octadiene-ligated iridium complex (Scheme 45b) [93]. This reaction proceeded under mild conditions with an extremely broad substrate scope, as well as excellent branched-to

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• whether stable meta-metalated calix[4]arenes could be formed, isolated and used. For this, our attention turned to the work of Albrecht and co-workers on mesoionic carbenes (MICs) [18][19][20][21][22], particularly the fact that 1,4-diphenyl-substituted 1,2,3-triazol-5-ylideneruthenium(II), iridium(III

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• ]. Many of these complexes contain rhodium or iridium coordinated with fully (methyl)substituted cyclopentadienyl ligands and bis-coordinating diamino ligands as shown in Figure 7. The reducing agent may be a formate anion as a source of hydride, triethanolamine as an electron donor in the case of

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• (55/55’ = 92:8) because of the preferential addition of hydrogen on the less hindered face of the trisubstituted alkene opposite to the trifluoroacetamide moiety. A reversal of face selectivity can be observed by performing a directed iridium(I)-catalyzed hydrogenation in the presence of Crabtree’s

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• (dtbbpy)PF4 as photocatalyst, and K2HPO4 as base in MeCN under the irradiation of 24 W blue LED light at room temperature for 12–36 h. A plausible mechanism is shown in Scheme 19. Firstly, the substrate 84a underwent oxidative quenching under the action of an iridium photoredox catalyst to afford the

Degenerative xanthate transfer to olefins under visible-light photocatalysis

• Atsushi Kaga,
• Xiangyang Wu,
• Joel Yi Jie Lim,
• Hirohito Hayashi,
• Yunpeng Lu,
• Edwin K. L. Yeow and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2018, 14, 3047–3058, doi:10.3762/bjoc.14.283

• degenerative transfer of xanthates to olefins is enabled by the iridium-based photocatalyst [Ir{dF(CF3)ppy}2(dtbbpy)](PF6) under blue LED light irradiation. Detailed mechanistic investigations through kinetics and photophysical studies revealed that the process operates under a radical chain mechanism, which

• is initiated through triplet-sensitization of xanthates by the long-lived triplet state of the iridium-based photocatalyst. Keywords: energy transfer; olefin; photocatalysis; radical; xanthate; Introduction A degenerative radical transfer of xanthates to olefins has been developed as a robust

• report a photocatalytic degenerative radical transfer of xanthates to olefins using an iridium-based photocatalyst under blue LED irradiation (Scheme 1C). A series of mechanistic investigations identified that the process involves a triplet-sensitization of the xanthates by the long-lived triplet state

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• -based complexes can be used into photoredox catalysis with suitable oxidation or reductive agents [37][38][39]. 2.1.1 The first generation of metal-based PCs: ruthenium and iridium complexes: The first generation of coordination compounds used for the photoredox catalysis comprises ruthenium and iridium

• can also be tuned by changing the metal. For example, smaller Stokes shifts are observed using iridium rather than ruthenium metal. That’s why Ir-based complexes have also been widely described in the literature as metal-based photoredox catalysts [19]. As an example, Ir(ppy)3 (abbreviation for tris(2

• -phenylpyridine)iridium) has been chosen and is depicted in Scheme 2. This metal complex is also commercially available. Ir(ppy)3 exhibits a MLCT transition in the near UV–visible range. The photochemical properties of this complex are gathered in Table 3. Interestingly, it is also possible to tune both the light

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• water) could reduce 1 to form Co(I) species upon irradiation with ultraviolet (UV) light. We also reported a visible-light-driven system with a molecular photosensitizer such as Ru(bpy)32+ [39][40][102][103], cyclometalated iridium(III) complexes [104], and organic red dyes [105][106][107]. 4-2

• iridium(III) complexes such as Irdfppy [112] are superior to [Ru(bpy)3]Cl2 in terms of their photosensitization abilities in visible-light-driven B12 catalytic systems (Scheme 9) [104]. This was probably due to the gradual decomposition of [Ru(bpy)3]Cl2 under visible light irradiation. This is consistent

Synthesis of aryl sulfides via radical–radical cross coupling of electron-rich arenes using visible light photoredox catalysis

• Amrita Das,
• Mitasree Maity,
• Simon Malcherek,
• Burkhard König and
• Julia Rehbein

Beilstein J. Org. Chem. 2018, 14, 2520–2528, doi:10.3762/bjoc.14.228

• -trimethoxybenzene in CH3CN. (b) Changes in the fluorescence spectra upon the addition of diphenyl disulfide in CH3CN. (c) Stern–Volmer quenching plot of iridium catalyst in the presence of 1,2,4-trimethoxybenzene and diphenyl disulfide. Kq (arene) = 318 ± 2.6 M−1 L and Kq (disulfide) = 36 ± 0.7 M−1 L. Black line

D-Fructose-based spiro-fused PHOX ligands: synthesis and application in enantioselective allylic alkylation

• Michael R. Imrich,
• Jochen Kraft,
• Cäcilia Maichle-Mössmer and
• Thomas Ziegler

Beilstein J. Org. Chem. 2018, 14, 2082–2089, doi:10.3762/bjoc.14.182

• crucial for further progress in stereoselective synthesis [5]. Privileged ligands often used are phosphinooxazoline ligands (PHOX ligands 1, (Figure 1)) which were developed in 1993 independently by Helmchen, Pfaltz and Williams [6][7][8]. Palladium– and iridium–PHOX complexes were already applied as

Recent advances in phosphorescent platinum complexes for organic light-emitting diodes

• Cristina Cebrián and
• Matteo Mauro

Beilstein J. Org. Chem. 2018, 14, 1459–1481, doi:10.3762/bjoc.14.124

• an efficient (external quantum efficiency, EQE, ca. 4%) OLED device [10]. Since that pioneering work, an impressive amount of research effort has been devoted in the last two decades to seeking for TMCs that display better device performances. In this respect, iridium(III) and platinum(II

• dopant materials. It is worth to note that optimized PhOLED device embedding complex 22c at doping concentration of 4 wt % showed an EQE of 22.1% that compares well with the best red-emitting iridium(III)-based devices. Complexes based on N^C^N ligands Although formally bearing similar coordinating units

• )/LiF/Al, OLED devices with peak EQE of 24.4% were fabricated. Such efficiency is comparable to the best blue iridium and platinum complexes reported so far. Two different classes of tetradentate platinum derivatives bearing N^C^C^N rigid ligands were recently reported by Wang and co-workers, bearing

D–A–D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies

• Lin Gan,
• Xianglong Li,
• Xinyi Cai,
• Kunkun Liu,
• Wei Li and
• Shi-Jian Su

Beilstein J. Org. Chem. 2018, 14, 672–681, doi:10.3762/bjoc.14.55

• %, when assuming the out-coupling efficiency to be 20%. On the other hand, phosphorescent materials could utilize triplet excitons in electroluminescence processes to achieve 100% IQEmax [2][3]. However, the utilization of metals like iridium and platinum, which are expensive and nonrenewable, inevitably

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

• % for phosphorescent OLEDs [5]. As drawback, triplet emitters are transition-metal complexes mostly based on iridium, platinum and osmium and the scarcity of these metals on Earth, their toxicity and high cost make these materials unsuitable candidates for a mass-production of OLEDs [6]. However

• 5 hours for T13-based OLEDs. A comparison established with an iridium complex, i.e., tris[1-(2,4-diisopropyldibenzo[b,d]furan-3-yl)-2-phenyl-1H-imidazole]iridium(III) (Ir(dbi)3) evidenced the relevance of the TADF approach, as a device lifetime of only 18 hours was found while operating OLEDs in the

• , but EL polymers substituted with iridium complexes have previously been studied in the literature, evidencing the pertinence of the strategy [61]. In this case, charge transport properties are provided by the substituents attached to the polymer chain. As main finding of this work, the detrimental