Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• reactivity with a few examples failing to provide the desired product when 4-CzIPN was used as the photocatalyst; however, the products were isolated when [Ir(dF(CF3)ppy)2(bpy)]PF6 was used. Based on experimental observations and control reactions, the authors proposed the reaction begins with the

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• lutidine base, 7 mol % organic photocatalyst 4CzIPN, 30 mol % NiBr2, and 30 mol % bpy provided 57% of 9. Intramolecular Friedel–Crafts reaction by Et2AlCl and HFIP complex led to 123, possessing the correct connectivity for the divergent synthesis of the family. Choreographically executed sequential

• ). Thus, upon irradiation, iridium polypyridyl photocatalyst allowed the oxidation of the phosphate complex 207 to radical cation 206, which can be readily trapped by TEMPO, and hence stabilizing the imine and allowing cyclization with the pendant amine to form the pyrroloindoline core 210 in 81% yield

• and 93% ee. The latter can serve as a common scaffold to access an array of pyrroloindoline natural products but also synthetic analogues (Scheme 17). Oxidation of 210 by a second iridium photocatalyst yields benzyl cation 213, which can undergo nucleophilic attack by tryptamine derivatives to allow

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• produced as byproduct in the metathesis reaction. Some subsequent publications include the Pd-complex removal after a Suzuki coupling [126], a Heck catalyst retention with reverse boiling-point-order solvent exchange [127], and a membrane for recovery of the photocatalyst TBADT (tetrabutylammonium

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

• simultaneous separation of both the photocatalyst and metal-catalyst is achieved. The combination of both catalytic activities in a single material is crucial to obtain this result, as a mixture of a heterogeneous photocatalyst with an immobilized metal catalyst would be problematic both in terms of packed bed

Radical cation Diels–Alder reactions of arylidene cycloalkanes

• Kaii Nakayama,
• Hidehiro Kamiya and
• Yohei Okada

Beilstein J. Org. Chem. 2022, 18, 1100–1106, doi:10.3762/bjoc.18.112

• Information File 96: General remarks, photocatalyst analyzation data, synthesis procedure, additional control studies, electrochemical measurements, and characterization data, including copies of 1H and 13C NMR spectra. Funding This work was supported in part by JSPS KAKENHI grant Nos. 16H06193, 17K19221

Electrochemical Friedel–Crafts-type amidomethylation of arenes by a novel electrochemical oxidation system using a quasi-divided cell and trialkylammonium tetrafluoroborate

• Hisanori Senboku,
• Mizuki Hayama and
• Hidetoshi Matsuno

Beilstein J. Org. Chem. 2022, 18, 1040–1046, doi:10.3762/bjoc.18.105

• -acyliminium ions in chemical methods has been generally accomplished by the reaction of amides with chemical oxidants, such as peroxides and persulfates at high temperature (path a in Scheme 1) [10][11][12][13]. A metal catalyst or a photocatalyst consisting of metals, such as ruthenium or iridium, is also

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

Tetraphenylethylene-embedded pillar[5]arene-based orthogonal self-assembly for efficient photocatalysis in water

• Zhihang Bai,
• Krishnasamy Velmurugan,
• Xueqi Tian,
• Minzan Zuo,
• Kaiya Wang and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2022, 18, 429–437, doi:10.3762/bjoc.18.45

• -acetonaphthone (2j, 50%, Figure S13) demonstrating the general applicability of m-TPEWP5G-EsY as an efficient photocatalyst. To understand the process for this photocatalytic dehalogenation reaction, a possible reaction mechanism is proposed in Figure 5 [37]. Upon light irradiation, the ground state of m-TPEWP5G

• UV light. Proposed mechanism for the 2-bromo-1-phenylethanone dehalogenation reaction mediated by m-TPEWP5G-EsY nanoassembly as a photocatalyst. Graphical representation of the fabrication of supramolecular m-TPEWP5G-EsY self-assembled photocatalytic system. Products from 2-bromo-1-phenylethanone

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

Recent advances and perspectives in ruthenium-catalyzed cyanation reactions

• Thaipparambil Aneeja,
• Cheriya Mukkolakkal Abdulla Afsina,
• Padinjare Veetil Saranya and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 37–52, doi:10.3762/bjoc.18.4

• 2021. Keywords: cyanation; nitriles; photocatalyst; ruthenium; tertiary amines; Introduction Nitriles are a major class of organic compounds having wide significance in materials science, agrochemical and pharmaceutical industry [1]. They are the privileged compounds finding broad applications in

• oxidative cyanation of aza-Baylis–Hillman adducts. Synthesis of 1° alkyl nitriles using [Ru(bpy)3](PF6)2 as the photocatalyst. Synthesis of 2° and 3° alkyl nitriles using [Ru(bpy)3](PF6)2 as the photocatalyst. Photoredox cross coupling reaction. Synthesis of α-amino nitriles from amines via a one-pot

DABCO-promoted photocatalytic C–H functionalization of aldehydes

• Bruno Maia da Silva Santos,
• Mariana dos Santos Dupim,
• Cauê Paula de Souza,
• Thiago Messias Cardozo and
• Fernanda Gadini Finelli

Beilstein J. Org. Chem. 2021, 17, 2959–2967, doi:10.3762/bjoc.17.205

• -bromobenzonitrile (2) under different amounts of DABCO. Two inorganic bases were tested: potassium carbonate (K2CO3) and sodium hydrogen carbonate (NaHCO3). Reactions in the absence of inorganic bases were also performed (Table 1). An excited iridium photocatalyst (Ir[dF(CF3)ppy]2(dtbbpy)PF6) was used for the one

• and 13), there was a significant improvement in the yield when using NaHCO3 (Table 1, entry 5), even when compared to the results obtained with K2CO3. No product was observed when the reaction was performed in the dark (Table 1, entry 7) or in the absence of the iridium photocatalyst (Table 1, entry 8

• radical hydrogen abstraction may be possible under similar conditions [31][32]. However, even small amounts of DABCO (Table 1, entry 1) seem to completely shut down this alternative path, probably due to a fast quenching of the excited state photocatalyst, leading to no mechanism competition under the

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

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

• the photocatalyst RuII is irradiated by light, an electron is transferred from the frontier metal d orbital (t2g orbital) to the ligand-centered π* orbital (RuII*). A metal-to-ligand charge transfer (MLCT) results in the excited singlet state. Through rapid intersystem crossing (ISC), the singlet

• thiocyanate to generate 4-alkyl/aryl-2-aminothiazoles. Mechanistic experiments demonstrated that the photocatalyst formed in situ from Cu(OAc)2 and ammonium thiocyanate promoted the intermolecular cyclization (Scheme 7). 3.2 Difunctionalization of alkenes The 1,2-difunctionalization of alkenes is a versatile

• absence of organic halide, the copper salts catalyzed the hydroamination of the alkene [59]. Mechanistic studies showed that the copper–amido complex coordinated with alkenes, which then acted as a primary photocatalyst. After light irradiation, the excited alkene–copper–amido species offered a benzyl

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• molecular properties of the intermediates and final products were evaluated by spectral and chromatographic analyses. Keywords: black phosphorus; click chemistry; heterogeneous photocatalyst; near infrared; phosphorene; Introduction For the last decade, click chemistry has been recognized as an

• sunlight, especially in the NIR region [28][29]. In particular, the development of new photocatalyst systems that absorb the incident light from the sun at much longer wavelengths have aroused widespread interest [30][31][32][33]. However, the most of the NIR photocatalysts applied exhibit relatively low

• black phosphorus (BP), the most stable allotrope of phosphorus, has been shown as a highly efficient photocatalyst possessing superior features in many respects [36][37]. BP, a vital semiconductor 2D material with excellent physicochemical properties such as high carrier mobility, tunable optical

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

• developments, which enables a diverse range of previously inaccessible organic transformations in milder reaction conditions [31][32][33][34][35][36][37][38][39][40]. Here, by absorbing visible light, a photocatalyst can function as a single-electron redox mediator through an oxidative or reductive quenching

• cycle (Figure 1), thereby facilitating redox-neutral transformations in the absence of stoichiometric oxidants/reductants. Given the tendency of nickel to mediate the reactions via Ni(0), Ni(I), Ni(II), and Ni(III) intermediates by both giving and accepting a single electron from a photocatalyst or

• , MacMillan and co-workers demonstrated an inspiring C(sp3)‒H arylation of dimethylaniline (1a) with a variety of aryl halides using the photoredox nickel catalysis [53]. Here, the combination of the iridium photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6 and the commercially available nickel catalyst NiCl2·glyme

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• this specific metal are highly desirable. Titanium is well known to be used as titanium dioxide, a powerful photocatalyst present in inks [61][62] and sunscreens [63][64]. As a catalyst, it can be used, for example, in polymerization methods to synthesize polypropylene [65]. With regard to C–H

• for the allylation of aldehydes promoted by a dual catalytic system comprising CrCl3 and an iridium-based photocatalyst that was recently developed by Schwarz and co-workers [119]. Similar conditions were further employed to synthesize monoprotected 1,2-homoallylic diols from aldehydes and silyl and

• are crucial. In 2018, Ackermann and co-workers described a novel room temperature C–H arylation by using a continuous visible light photo-flow technique, allied with a manganese photocatalyst CpMn(CO)3 [142]. The new flow protocol enabled the synthesis of several arene- and heterocyclic-based

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• is also oxidized to Mn(III)/L–N3. Azide radical addition to Mn(II)/L to form Mn(III)/L–N3 was considered as a possible route. Concurrently, the photocatalyst is irradiated by blue LED light to induce hydrogen atom transfer (HAT) at the C–H bond of substrate 12, generating alkyl radicals and enabling

• C–N3 bond formation to afford 13 via the reaction with Mn(III)/L–N3. The anodic surface oxidizes the radical adjacent to the hydroxy group of the photocatalyst, thereby regenerating it. At the same time, the hydrogen atom abstraction of radical species of photocatalyst by Mn(III)–N3 could not be

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

• Girish Suresh Yedase,
• Sumit Kumar,
• Jessica Stahl,
• Burkhard König and
• Veera Reddy Yatham

Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121

• , Universitätstraße 31, D-93053 Regensburg, Germany 10.3762/bjoc.17.121 Abstract We have developed a cerium-photocatalyzed aerobic oxidation of primary and secondary benzylic alcohols to aldehydes and ketones using inexpensive CeCl3·7H2O as photocatalyst and air oxygen as the terminal oxidant. Keywords: alcohol

• air as the oxidant (Table 1). The best results were found using 10 mol % CeCl3·7H2O as a photocatalyst and 10 mol % of NaHCO3 as a base in CH3CN under blue LED irradiation at 50 °C for 35 h giving compound 2a in 65% isolated yield (Table 1, entry 1). The product formation was reduced upon employing

• and secondary benzylic alcohols were converted into the corresponding aldehydes and ketones in good to moderate yields using commercially available and inexpensive CeCl3·7H2O as a photocatalyst and air as an oxidant. Mechanistic studies. (A): UV–vis spectra of the CeIV(OBn)Cln complex in CH3CN under

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• ) [121]. Notably, the organic photocatalyst eosin Y was employed, and the cyclizations proceeded with excellent diastereoselectivity, usually higher than 19:1. When 1,3-ketocarbonyl substrates 100 were employed, the use of a weak Lewis acid (LiBr) was required to accomplish the cyclizations, and no

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

• .17.89 Abstract A visible light-mediated heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile has been established using K-modified carbon nitride (CN-K) as a recyclable semiconductor photocatalyst. This protocol, employing readily accessible alkyl N-hydroxyphthalimide (NHPI

• ]. In the last few years, carbon nitride-based heterogeneous photocatalysts have also been utilized for several other radical-initiated synthetic transformations [44][45][46][47][48][49][50][51][52][53][54][55][56]. However, to the best of our knowledge, the application of a CN-based photocatalyst for

• ). Traditional g-C3N4 exhibited a low catalytic activity for this transformation (Table 1, entry 6). Switching from CN-K to a homogeneous organo photocatalyst such as eosin Y and 4CzIPN, led to lower yields of the desired product (Table 1, entries 7 and 8). The expensive Ru/Ir-based metal complexes gave similar

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

• has attracted more and more chemists and provided new opportunities for synthetic chemistry [8]. Moreover, diverse photocatalyst-free photochemical reactions have been employed to construct carbon–carbon and carbon–heteroatom bonds [9]. Among these methods, the product formations by aid of EDA

• construction of C–S bonds C–S bonds are commonly present in amino acids, proteins, glycosides, nucleic acids, and other biological macromolecules. In recent years, photocatalyst- and transition-metal strategies have been employed to construct C–S bonds [66][67][68][69]. The C–S bond synthesis via EDA-complex

• step without any transition-metal catalyst, ligand, or photocatalyst, this method possesses a splendid application prospect. The reaction mechanism is as follows (Scheme 48): Firstly, carbon disulfide combines with N-methylaniline (134) in the presence of Cs2CO3 to form thiolate 136. Thiolate 136 is

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

• photocatalyst and KH2PO4 (10 mol %) as the base (Table 1, entry 1). The yield of 4a was not increased when 2 equiv of K2HPO4 were used (Table 1, entry 2) and no difunctionalized product was observed with DMA as the solvent (Table 1, entry 4). The employment of KH2PO4 as base and [Ir(dF(CF3)ppy)2(dtbby)]PF6 as

• the photocatalyst furnished the product in very low yields (Table 1, entries 3 and 5). The control experiments indicated that 4CzIPN, K2HPO4 or visible-light were indispensable for the reaction to proceed (Table 1, entries 6–8). With the optimized reaction conditions determined, we next examined the

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• between thiol-functionalized β-CD and oleic acid-protected CdS nanocrystals [29]. These spherical CdS–CD nanoparticles could be employed as a photocatalyst for the dehydrogenation of alcohols to aldehydes (at a low concentration of the reactant of 1 mM, ≥92% selectivity) or diols (at a high concentration

• of the reactant of 300 mM, ≥93% selectivity), with H2 liberation being achieved by visible-light irradiation in an aqueous solution. In comparison, CdS–CD was a highly efficient photocatalyst for benzyl alcohol dehydrogenation (77 µmol H2 in 180 h) compared to the CD-free CdS (5.4 µmol H2 in 30 h

• activity (618.3 mmol⋅g−1⋅h−1) and an excellent stability (with a turnover number (TON) of 6417 after 75 h). Moreover, when the electron donor 1,3-dimethyl-2-phenyl-1,3-dihydrobenzimidazole (BIH) was added, the hybrid material functioned as an efficient photocatalyst for the reduction of CO2 to CO with 0.26

Synthesis of tetrafluorinated piperidines from nitrones via a visible-light-promoted annelation reaction

• Vyacheslav I. Supranovich,
• Igor A. Dmitriev and
• Alexander D. Dilman

Beilstein J. Org. Chem. 2020, 16, 3104–3108, doi:10.3762/bjoc.16.260

• photocatalyst activated by blue light. The annelation is a result of a radical addition at the nitrone, intramolecular nucleophilic substitution, and reduction of the N–O bond. Keywords: difluoroalkylation; nitrones; organofluorine compounds; photocatalysis; radical addition; Introduction Nitrogen-containing

• photocatalyst and stoichiometric quantities (1.2 equiv) of a reducing system (ascorbic acid/collidine). In this reaction no products were formed with reactant 2a remaining unconsumed (Table 1). To obtain a more reactive fluorinated halide, the bromine atom residing at the fluorinated moiety was exchanged for

• in Scheme 3. The iridium(III) photocatalyst under the action of light and ascorbic acid generates the iridium(II) species. The latter serves as a key reducing agent, and importantly, its formation is maintained throughout the process while an excess amount of ascorbate is present. The annelation