Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• . The acridinium ion 161 now takes on the additional role of a phase-transfer catalyst, facilitating the transport of the chloride ion into the lipophilic alkene phase. Subsequently, under irradiation with blue LEDs, the acridinium cation 161 and the chloride anion engage in a single-electron-transfer

SOMOphilic alkyne vs radical-polar crossover approaches: The full story of the azido-alkynylation of alkenes

• Julien Borrel and
• Jerome Waser

Beilstein J. Org. Chem. 2024, 20, 701–713, doi:10.3762/bjoc.20.64

• source such as green LEDs or a compact fluorescent lamp (CFL) were used only a small decrease in yield could be observed, although 4 hours of irradiation were needed to reach full conversion using CFL (Table 5, entries 8 and 9). The concentration, a factor expected to play an important role in a three

Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor

• Pengcheng Li,
• Daniel Kowalczyk,
• Johannes Liessem,
• Mohamed M. Elnagar,
• Dariusz Mitoraj,
• Radim Beranek and
• Dirk Ziegenbalg

Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9

• (LEDs) have plenty of advantages including long life span (up to 100 000 h), robustness, compact size, and high energy efficiency, which make LEDs very attractive as a light source for photocatalytic hydrogen generation studies [29]. In this work, a loop photoreactor for scaling up the photocatalytic

• hydrogen generation is designed and equipped with 365 nm LEDs. Fluid dynamics in the loop photoreactor are characterized using a color tracer mixing experiment and image analysis. Photonic characterization is performed with the ferrioxalate actinometer. Finally, the photocatalytic hydrogen evolution with

• . Photonic characterization The loop photoreactor using 6 LEDs was photonically characterized by chemical actinometry. Figure 6 shows the actinometer conversions and calculated photon fluxes at different irradiation times. The reasonable linear fits of the conversion (see Figure 6a) prove the applicability

Thienothiophene-based organic light-emitting diode: synthesis, photophysical properties and application

• Recep Isci and
• Turan Ozturk

Beilstein J. Org. Chem. 2023, 19, 1849–1857, doi:10.3762/bjoc.19.137

• many applications such as OLEDs, micro-LEDs, LCDs, lasers, and photodiodes by applying thin film methods and solution processes [5][6][7][8]. The performance of organic electronics is based on the active layer composition as well as the fabrication methods and processing parameters. The organic active

Recent advancements in iodide/phosphine-mediated photoredox radical reactions

• Tinglan Liu,
• Yu Zhou,
• Junhong Tang and
• Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

• approach. Importantly, the demonstration of the exceptional compatibility between blue LEDs and diazirine compounds also held the promise of inspiring further exploration and development of novel synthetic strategies in this field. Enamides are commonly found in medicinal compounds and physiologically

• depicted in Scheme 16. Initially, a photoactive EDA complex II was transiently formed through the combined action of NaI, PPh3, and the γ,σ-unsaturated phthalimide 33a. Upon irradiation with blue LEDs, the alkyl radical A was generated through a single-electron transfer from the iodide anion to the γ,σ

Visible-light-induced nickel-catalyzed α-hydroxytrifluoroethylation of alkyl carboxylic acids: Access to trifluoromethyl alkyl acyloins

• Feng Chen,
• Xiu-Hua Xu,
• Zeng-Hao Chen,
• Yue Chen and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2023, 19, 1372–1378, doi:10.3762/bjoc.19.98

• under the irradiation of purple LEDs afforded the desired coupling product 3a in 50% yield (Table 1, entry 1). Further screening of other activators (Table 1, entries 2–5) indicated that pivalic anhydride (A3) was optimal, delivering 3a in 56% yield. The yield of 3a was increased to 74% when 3.0 equiv

• LEDs (λmax = 399 nm) for 7 h. After the reaction was complete, the reaction mixture was poured into water and extracted with EtOAc. The combined organic phase was separated and washed with brine, dried over Na2SO4, and concentrated under vacuum. The resulting residue was purified by silica gel flash

• mmol), NiBr2(dtbbpy) (0.04 mmol), Hantzsch ester (0.6 mmol), Piv2O (0.6 mmol) and H2O (1.2 mmol) in DMAc (4.0 mL) was irradiated by purple LEDs for 7 h. Isolated yields are presented. aThe reaction was performed in a 1.0 mmol scale. Optimization of the reaction conditions.a Supporting Information

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• source played a key role, with lower yields or no product obtained when the reaction was performed without water or under other light source conditions such as 19 W CFL or irradiation with blue or green LEDs. This method is applicable to various heteroatom-containing compounds such as quinolines

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• ) wavelength LEDs that complicate the setup. The simpler reaction setups and lack of a heterogeneous surface (electrodes) can make the mechanistic investigation more accessible. While quantum parameters (quantum yield, quadratic relationships with light intensity, etc) have been touched upon for a

• qualitative description is used as per the report in question (e.g., ‘blue LEDs’). The König group first reported a photocatalytic approach to C(sp2)–X activation harnessing multiple photon energies in their seminal work on perylene diimide (PDI) catalysts [15]. In their proposed consecutive photoinduced

• radical. This is strongly supported by a single turnover experiment, where exclusive excitation of [FeII(btz)3]2+ with 700 nm LEDs after in situ generation and substrate addition in the dark generated 5% of product even with only 0.5 mol % of catalyst present. In its ground state, [FeII(btz)3]2+ is not

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• compound 5 in hand, the required radical–radical coupling was investigated next, and some of the representative results are shown in Table S1 (see Supporting Information File 1). Irradiation from blue light-emitting diodes (LEDs) in the presence of 2 mol % of the photocatalyst [Ir(dF(CF3)ppy)2(dtbpy)]PF6

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

• Deepak Singh,
• Shyamal Pramanik and
• Soumitra Maity

Beilstein J. Org. Chem. 2023, 19, 666–673, doi:10.3762/bjoc.19.48

• reaction was carried out between 1a and 2a in dry CH3CN as solvent under N2 atmosphere using 4CzIPN as the photocatalyst. Irradiating the reaction mixture for 10 h under blue LEDs (450 nm) led to the isolation of products 5 (54%) and 6 (28%) (Table 1, entry 1). However, the same reaction, under aerobic

• photocatalyst 10-phenylphenothiazine (PTH) under violet LEDs which uplifted the yield up to 52% (Table 1, entry 7). Now with the optimal catalyst in hand, we screened some common solvents, out of which 1,2-DCE positively impacted the yield (Table 1, entries 8–11). However, the best result was obtained when 3.0

• functionalizations of IPs and present work. Substrate scope. Conditions: unless otherwise noted, all reactions were carried out with 1 (0.2 mmol), 2 (0.4 mmol), PTH (5 mol %), Zn(OAc)2 (0.6 mmol), dry 1,2-DCE (2 mL), irradiation with LEDs (λmax = 390 nm), under air for 10 h. Mechanistic investigations. Plausible

NaI/PPh₃-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

• Dan Liu,
• Yue Zhao and
• Frederic W. Patureau

Beilstein J. Org. Chem. 2023, 19, 57–65, doi:10.3762/bjoc.19.5

• Discussion Key elements of reaction optimization are summarized in Table 1. With NaI (20 mol %) and PPh3 (20 mol %), acrylamide 1a and redox-active ester 2a were used as model substrates to react for 36 h in acetonitrile (MeCN) under blue LEDs irradiation and N2 atmosphere, delivering the desired oxindole

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• radical (SPyf, Scheme 24) was proposed as a hydrogen atom abstracting agent for unactivated C–H bonds of alkanes and other CH-reagents [123] (Scheme 24). It was generated by the irradiation of the corresponding disulfide with 400 nm LEDs. In the proposed catalytic cycle tetrafluoropyridinyl thiol HSPyf is

Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor

• Wei-Hsin Hsu,
• Susanne Reischauer,
• Peter H. Seeberger,
• Bartholomäus Pieber and
• Dario Cambié

Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115

• visible-light photocatalysts that enable new reaction pathways that were previously difficult or impossible to realize [2]. Technical advancements, such as the rise of light-emitting diodes (LEDs) and new reactor technologies were similarly important incentives to popularize light-mediated organic

• radiated with 440 nm LEDs at 55 °C. A poor yield (16%) was obtained using a residence time of 3 hours. This result called for a more detailed investigation of crucial reaction parameters to understand if the limitation is of catalytic or technological nature. Steady-state and automated reaction analysis To

Introducing a new 7-ring fused diindenone-dithieno[3,2-b:2',3'-d]thiophene unit as a promising component for organic semiconductor materials

• Valentin H. K. Fell,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Eman J. Hussien and
• Peter J. Skabara

Beilstein J. Org. Chem. 2022, 18, 944–955, doi:10.3762/bjoc.18.94

• (the basic unit of processors) [6], solar cells, and LEDs [7]. Inorganic compounds, e.g. III-V type inorganics are widely used, however, in recent years, organic molecules with semiconducting and fluorescent properties have emerged as an alternative with advantages such as solution processing [8][9][10

High-speed C–H chlorination of ethylene carbonate using a new photoflow setup

• Takayoshi Kasakado,
• Takahide Fukuyama,
• Tomohiro Nakagawa,
• Shinji Taguchi and
• Ilhyong Ryu

Beilstein J. Org. Chem. 2022, 18, 152–158, doi:10.3762/bjoc.18.16

• the reaction and the system should be kept dry for continuous production. We are now investigating some other photo gas–liquid flow reactions, which will be reported in due course. Experimental The photoflow setup consisting of a flow photoreactor LX-1 and UV-LEDs were supplied from MiChS Inc., Ltd

Synthesis of highly substituted fluorenones via metal-free TBHP-promoted oxidative cyclization of 2-(aminomethyl)biphenyls. Application to the total synthesis of nobilone

• Ilya A. P. Jourjine,
• Lukas Zeisel,
• Jürgen Krauß and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2668–2679, doi:10.3762/bjoc.17.181

• electronic and optical properties [16][17][18][19][20][21], utilized in LEDs, semiconducting polymers, and solar cells. Consequently, synthetic approaches to fluorenones have attracted large interest and numerous methodologically diverse approaches have been published in the past decades. Among these are

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• . Under optimized conditions, the substrate scope was examined and determined to include activated olefins, unactivated olefins, and arylalkynes. In parallel, Hu and co-workers [51] reported the photoinduced, copper-catalyzed chlorosulfonylation of alkenes and alkynes under irradiation with blue LEDs

A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

• Pieterjan Winant and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 2315–2320, doi:10.3762/bjoc.17.149

• through oxidative quenching of the excited substrate. While an excited state of 1 could react in a similar fashion, the absorption maximum of 1 is centered around 280 nm, which is outside the emission spectrum of green LEDs. A recent study by Hashmi et al. [44], however, shed a completely different light

• investigate the transferability of this concept to our system, the light source was changed to blue LEDs. This change seemed to increase reactivity, observed by significantly more vigorous nitrogen release, resulting in shortening of the reaction time to 2 h. The reaction yield on the other hand was slightly

• lower as compared to when green LEDs were used. Based on the report by Hashmi, we hypothesize that the overlap in wavelengths emitted by both green and blue LEDs cause the reaction to work in both instances. The diminished intensity of shorter wavelengths in the green LED causes a slower, more

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• of aryl chlorides 8 through selective 2-functionalization of 1,3-dioxolane (13) followed by a mild acidic workup (Scheme 9) [61]. Here, the photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and nickel catalyst NiCl2·DME with dtbbpy as ligand, along with K3PO4 as base under irradiation with blue LEDs enabled

• efficient HAT photocatalyst to perform the desired C–H abstraction (Scheme 10) [62]. The catalytic reaction required near-ultraviolet light irradiation (Kessil 34 W 390 nm LEDs) and the exclusion of both oxygen and water to the success of the reaction. A variety of cyclic, acyclic, and bicyclic aliphatic

• under irradiation of blue LEDs at ambient temperature afforded the desired α-arylation products 32 from secondary amides 31 and (hetero)aryl bromides 3 (Scheme 18) [72]. The method showed a broad substrate scope for both amides and aryl bromides. The authors also realized the enantioselective variant of

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile: synthesis of diverse nitrogenous heterocyclic compounds

• Guanglong Pan,
• Qian Yang,
• Wentao Wang,
• Yurong Tang and
• Yunfei Cai

Beilstein J. Org. Chem. 2021, 17, 1171–1180, doi:10.3762/bjoc.17.89

• recycling. Reaction conditions: 1a (0.1 mmol, 1 equiv), 2d (0.2 mmol, 2 equiv), CH3CN (6 mL), CN-K (1 mg/mL), 2 × 24 W blue LEDs (460 ± 5 nm) without extra heating (at 40–45 °C). After each reaction, the catalyst was recovered by centrifugation and reused in the next cycle. CN-K-Catalyzed

• cyanomethylarylation of alkenes to access diverse heterocyclic compounds. CN-K-catalyzed cyanomethylarylation of N-arylallylamines for the synthesis of indolines. Reaction conditions: 1 (0.2 mmol, 1 equiv), 2d (0.4 mmol, 2 equiv), CH3CN (8 mL), CN-K (1 mg/mL), 2 × 24 W blue LEDs (460 ± 5 nm) without extra heating (at

• 40–45 °C). aPerformed with 0.017 M of 1. CN-K-catalyzed cyanomethylarylation of N-benzoylallylamines for the synthesis of isoquinolinones. Reaction conditions: 5 (0.2 mmol, 1 equiv), 2d (0.6 mmol, 3 equiv), CH3CN (8 mL), CN-K (1 mg/mL), 2 × 24 W blue LEDs (460 ± 5 nm), 60 °C. CN-K-catalyzed

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• tetramethylethylenediamine (TMEDA) as additive in the EDA complex formation with perfluoroalkyl iodides 42 to afford 2-perfluoroalkylbenzothiazole products 43, employing blue LEDs (25 W) as irradiation source (Scheme 14). Notably, as (2-isocyanophenyl)(methyl)selane was exploited instead of substrate 41, new

• in 158. Significantly, in contrast to most traditional EDA complex approaches that consume the DA pair, the electron-donor catalyst q-OAc in this method could be regenerated. In 2019, Frontera and colleagues [49] obtained target product 162 with blue LEDs irradiation of a solution containing electron

Metal-free visible-light-enabled vicinal trifluoromethyl dithiolation of unactivated alkenes

• Xiaojuan Li,
• Qiang Zhang,
• Weigang Zhang,
• Jinzhu Ma,
• Yi Wang and
• Yi Pan

Beilstein J. Org. Chem. 2021, 17, 551–557, doi:10.3762/bjoc.17.49

• of blue LEDs, allyl boronate 1a (0.1 mmol), disulfide 2a (1.0 equiv) and N-(trifluoromethylthio)phthalimide (Phth-SCF3, 3, 1.5 equiv), the desired trifluoromethylthiolated product 4a was obtained in 71% yield with 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN, 2 mol %) as the

Benzothiazolium salts as reagents for the deoxygenative perfluoroalkylthiolation of alcohols

• Armin Ariamajd,
• Nils J. Gerwien,
• Benjamin Schwabe,
• Stefan Dix and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2021, 17, 83–88, doi:10.3762/bjoc.17.8

• the perfluoroisopropyl species BT-SCF(CF3)2. Each reagent was synthesized according to the two-step procedure shown in Scheme 2. Firstly, MBT was reacted with a perfluoroalkyl iodide and NaH in DMF under irradiation with UVA LEDs (λmax = 365 nm). In all cases, efficient S-perfluoroalkylation was

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

• same group reported the use of the same reaction in a commercial microchip (Micronit Microfluidics FC_R150.676.2) with an internal volume of 15 µm. This microchip was illuminated by 6 × 75 mW LEDs. The DMBP concentration was 6.7 mM, which resulted in around 95% light transmission through 150 µm channel

• 1.4 min. This reaction could be scaled up using other Corning reactors. For example, if the same conditions could be maintained in a Corning G3 reactor, this reaction would have a productivity of 100 mol/day [45]. The power consumption of the LEDs was not reported in the paper. Therefore, the PSTY

• packed bed reactor so that several microchannels were created among the beads. Glass beads were coated with a TiO2 photocatalyst. The photoreactor was illuminated with 192 LEDs that could provide 100 mW of power each. The distance between the LED board and the reactor was adjusted to give a uniform