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

• ]. In 2019, the Prato group demonstrated how the PDI catalyst first disclosed by the König group (vide supra) could be leveraged for conPET reductions of perfluoroalkyl iodides, providing a photocatalytic alternative for the generation of perfluoroalkyl radicals used in atom transfer radical addition

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

• )PF6 (E1/2*III/II = +1.21 V, E1/2III/II = −1.37; E1/2IV/*III = −0.89, E1/2 IV/III = +1.69 V) [74] would permit efficient radical generation and C(sp3)–C(sp3) bond formation either by challenging selective radical–radical cross-coupling or by radical addition to a π-bond, enabling a rare example of

• diene [90][91]. In addition, these results support the hypothesis that the decarboxylative cyclization can occur through subsequent selective 6-exo-trig radical addition. It also has been reported that it is difficult to detect which intermediate is really involved, since they are easily

• radical addition–fragmentation on the latter and most likely to shift the regioselectivity towards 6-exo-trig by a favorable interplay of polar effects [99] failed and furnished only the 1,3-diene 10. Unfortunately, when substrate 10 was subjected to the reaction conditions shown above, only tarry

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

• in the formation of spirolactam 157 in 73% yield (Scheme 13). The reaction is estimated to take place initially with the one electron reduction to α-amino radical 164. This step is thought to be facilitated after TFA protonates the formed imine. Afterwards, radical addition of 164 to 156, generates

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

• -coupling involving aldehyde C–H bond cleavage. DABCO-derived cationic catalysts in inactivated C–H bond cleavage for alkyl radical addition to electron-deficient alkenes under photoredox catalysis conditions. Electrochemical diamination and dioxygenation of vinylarenes catalyzed by triarylamines

A Streptomyces P450 enzyme dimerizes isoflavones from plants

• Run-Zhou Liu,
• Shanchong Chen and
• Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

• , Supporting Information File 1). Other plant polyketides, such as anthraquinones 19 and 20 and phenylpropanoids 21–24, failed to be dimerized. The reaction mechanism of P450-mediated phenol dimerization is believed to involve oxidative radical–radical coupling, though other mechanisms, such as radical

• addition, radical cation addition, and electrophilic aromatic addition, have also been proposed [1][10][29]. A proposed mechanism is depicted in Scheme 2: First, the hydroxy group on the A- or B-ring is converted into a radical by a P450-induced single-electron transformation. The resulting radical then

Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds: density functional theory study on product selectivity

• Naoki Kise and
• Toshihiko Sakurai

Beilstein J. Org. Chem. 2022, 18, 956–962, doi:10.3762/bjoc.18.95

• Scheme 5. The first one is a radical addition of O-trimethylsilyl radical A, which is formed by a one-electron reduction of 1 and subsequent O-trimethylsilylation, to 2a and a following one-electron reduction of the resultant radical B to give enolate anion D (path a). The second one is an anionic

• acrylate (2c) is much less reactive as an acceptor in this reaction as shown in Scheme 6. The main product in this case was the same dimeric phthalide 9 as the product without the acceptor. These results suggest that this reaction proceeds with the radical addition of A to form anion D (path a). Next, the

Synthesis of α-(perfluoroalkylsulfonyl)propiophenones: a new set of reagents for the light-mediated perfluoroalkylation of aromatics

• Durbis J. Castillo-Pazos,
• Juan D. Lasso and
• Chao-Jun Li

Beilstein J. Org. Chem. 2022, 18, 788–795, doi:10.3762/bjoc.18.79

• -sulfonylpropiophenone moiety readily undergoes homolysis into three parts upon irradiation of light: a propiophenone radical – forming a stabilized and bulky “dummy group” –, a molecule of SO2, and our radical of interest. Once this radical is formed in solution, radical addition to the aromatic substrate undergoes

• ), both in less than 6 hours (Scheme 5). Unsubstituted arenes such as naphthalene were well tolerated in this methodology and produced 72% isolated yield of the perfluorohexylated product 11b. The radical addition to unsubstituted benzene was also found to be possible affording perfluorooctylated product

Structural basis for endoperoxide-forming oxygenases

• Takahiro Mori and
• Ikuro Abe

Beilstein J. Org. Chem. 2022, 18, 707–721, doi:10.3762/bjoc.18.71

• changes of the active site residues on flexible loops would relocate the C13 radical intermediate, to prevent the hydroxy-rebound from the Fe(III)-OH species. Alternatively, the C13-radical reacts with molecular oxygen to form a peroxyl radical intermediate, which undergoes radical addition to C2' to

Direct C–H amination reactions of arenes with N-hydroxyphthalimides catalyzed by cuprous bromide

• Dongming Zhang,
• Bin Lv,
• Pan Gao,
• Xiaodong Jia and
• Yu Yuan

Beilstein J. Org. Chem. 2022, 18, 647–652, doi:10.3762/bjoc.18.65

• -electron transfer (SET) between CuBr and intermediate 5 forms intermediate 6, which initiates the N–O bond homolytic cleavage resulting in forming an N-centred phthalimidyl radical 7 (PhthN•) and anion 8. Meanwhile, Cu(I) is oxidized to Cu(II) in this step. Next, radical 7 attacks the benzene via radical

• addition to generate the intermediate 9, which is oxidized by Cu(II) to give 10, which undergoes aromatization and deprotonation to afford the product 3a. At this stage, Cu(I) is regenerated to complete the catalytic cycle. Conclusion In summary, we have developed a convenient copper-catalyzed method for

BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• radical addition of a thiol-based stopper to the α,β-unsaturated carbonyl unit in 12% yield. In this reaction, addition of the thiyl radical to the β-position first gives rise to the corresponding rotaxane radical with the unpaired electron in the α-position, followed by hydrogen abstraction from the next

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

• studies developed by Naturale’s group, α-, β-, and γ-amino acids of linear and branched chains were used, as well as different amine protection groups (Table 5). The results revealed that the functionalization of naphthoquinones by a radical addition of decarboxylated α-, β- and γ-N-protected amino acids

Site-selective reactions mediated by molecular containers

• Rui Wang and
• Yang Yu

Beilstein J. Org. Chem. 2022, 18, 309–324, doi:10.3762/bjoc.18.35

• mixture of different products will form through various pathways [50][51][52][53]. By applying the cage host A, the authors realized a highly site-selective radical addition reaction of o-quinone 10 and substituted toluene 11, giving rise to the unusual 1,4-adduct 15 (Figure 3) [54]. Specifically, upon

• naphthalene and phthalimide mediated by cage host A. Cage host A-mediated selective 1,4-radical addition of o-quinone 10. Cyclodextrin-mediated site-selective reductions. Selective reduction of an α,ω-diazide compound mediated by water-soluble cavitand D. Selective radical reduction of α,ω-dihalides mediated

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

• initiated, the reaction will propagate, which typically involves the insertion of a π-system (carbometallation of alkenes/alkynes) in the case of organoiron species (Scheme 2). Alternatively, the generated radical species may undergo radical addition to alkenes, alkynes, or aromatic arenes. The final step

• is the termination of the reaction through the trapping of the reactive intermediate. Organoiron complexes have been shown to undergo electrophilic trapping with external species or proceed through cross-coupling eventually undergoing reductive elimination. Radical addition will typically conclude

• sterically hindered tertiary alkyl bromides, the authors were able to favor intermolecular radical addition of the generated alkyl radical 17 to the vinylcyclopropane, outcompeting radical rebound to an aryl Fe species. The incipient radical can then undergo ring-opening of the cyclopropane 18. Work by

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

• strategy for the construction of complex molecules. The primary process involved in the 1,2-difunctionalization of alkenes catalyzed by copper complexes is an atom-transfer radical addition (ATRA). Copper complexes or copper-based photoredox-active complexes formed in situ serve as photocatalysts to

• undergoes radical addition with the N-substituted maleimide (Scheme 25). In 2017, Wu and co-workers [94] reported the α-amino C−H functionalization of aromatic amines 51 with nucleophiles, including arynes or aromatic olefins 52, indoles, acyclic β-ketoester 53, and β-diketone 54 (Scheme 26). Mechanistic

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• -annulation reaction may undergo a free-radical addition pathway. Firstly, NFSI oxidizes Cu(I) to form bissulfonylamidyl radical 10. Secondly, intermolecular nitrogen free-radical addition to the alkyne provides the vinyl radical 11. Then, there may be two possible pathways. Path a: vinyl radical 11 is

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

• computational studies highlight the involvement of hydrogen bonding assistance during the radical addition to olefine. The proposed reaction mechanism has two synergistic catalytic cycles, namely a photocatalytic cycle and a nickel catalytic cycle (Figure 23). The photoexcitation of the ketone PC 96 results in

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• proved to not going via a Minisci-type silyl radical addition [55], as the reaction with pyridine did not afford any product. Bell studied the properties of such molecules which are similar to those used in OLED devices (organic light emitting diodes) in 2017. The molecule 34 was synthesized by base

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

Correction: Amine–borane complex-initiated SF₅Cl radical addition on alkenes and alkynes

• Audrey Gilbert,
• Pauline Langowski,
• Marine Delgado,
• Laurent Chabaud,
• Mathieu Pucheault and
• Jean-François Paquin

Beilstein J. Org. Chem. 2021, 17, 1725–1726, doi:10.3762/bjoc.17.120

• , France 10.3762/bjoc.17.120 Keywords: amine–borane complex; pentafluorosulfanyl chloride; pentafluorosulfanyl substituent; radical addition; radical initiation; The stereochemistry of some alkene products (2i–k) in Scheme 4 of the original publication was misattributed. The corrected structures are

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

• reactions an ideal platform for the synthesis of molecules with increased molecular complexity. Keywords: hydroalkylation; hydrogen atom transfer; quaternary carbon center; radical addition; unactivated olefins; Introduction Natural product structures remain some of the main sources of inspiration for the

• radical conjugate addition triggered by the HAT process (see Scheme 22 intermediate D) allowed the construction of complex polycyclic units containing quaternary carbon centers. In the first case, a cascade radical addition/conjugate addition promoted by a HAT process to the terminal olefin of 53 (Scheme

•  23A) afforded trans-decalin 54 as the major diastereomer [83]. In the second case, a radical addition/aldolization was successfully developed to afford another trans-decalin unity as a major diastereomer in a 10:1 diasteroisomeric ratio (Scheme 23B, 57) [84]. Notably, in both cases, four contiguous

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

• recyclability, broad substrate scope, and high functional group tolerance (Scheme 1). Results and Discussion Our initial investigation focused on the CN-K photocatalyzed cascade alkyl radical addition/cyclization reaction of the N-arylallylamine 1a with tert-butyl N-hydroxyphthalimide (NHPI) ester (2a), a

• experiments was performed (Scheme 7). The cyanomethylarylation reaction of 7a gave the desired compound 8a as the major product in 70% yield, along with 23% yield of the byproduct 15. The latter compound was generated through a cascade alkyl radical addition/cyclization of the NHPI ester 2d to N-aryl

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

Highly regio- and stereoselective phosphinylphosphination of terminal alkynes with tetraphenyldiphosphine monoxide under radical conditions

• Dat Phuc Tran,
• Yuki Sato,
• Yuki Yamamoto,
• Shin-ichi Kawaguchi,
• Shintaro Kodama,
• Akihiro Nomoto and
• Akiya Ogawa

Beilstein J. Org. Chem. 2021, 17, 866–872, doi:10.3762/bjoc.17.72

• variety of terminal alkynes including both alkyl- and arylalkynes. Keywords: (E)-1,2-bis(diphenylphosphino)ethylene derivative; radical addition; stereoselective phosphinylphosphination; terminal alkyne; tetraphenyldiphosphine monoxide; Introduction Organophosphorus compounds are an essential class of

• 1,2-bis(diphenylphosphino)ethylenes, we have recently been conducting systematic research on the radical addition of P–P bond compounds to unsaturated carbon–carbon bonds [38][39][40][41][42][43][44]. Early studies have found that the radical addition of tetraphenyldiphosphine (Ph2PPPh2) to alkynes

• reactivity of the P–P bond, therefore, when the combination of pentavalent phosphorus and trivalent phosphorus was examined, it was found that the desired radical addition of Ph2P(X)PPh2 (X = O, S) to alkenes successfully occurred [42][43] (Scheme 1c and 1d). However, in the case of Ph2P(O)PPh2, its

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• give methanofullerenes Scientists are currently focusing on methods for the functionalization of the fullerene core that provide a high selectivity and yield. The electron-deficient polyene C60 readily undergoes radical addition, nucleophilic addition, and cycloaddition processes. Therein, the decrease

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

• conditions. In the previous research on the radical addition to nitrones we sometimes encountered a fluoroalkylation of the aromatic rings, if an excess of the fluorinated alkyl iodide was used [22][23][24]. This prompted us to attempt the reaction with an equimolar amount of the iodide 2b, which resulted in