Systematic structural variation and visualization of chemical shielding tensors (VIST) provide unique insights into the properties of π-conjugated macrocycles

π-Conjugated macrocycles are molecules with unique properties that are increasingly exploited for applications. Their study began in the early 1960s and many π-conjugated macrocycles have been synthesized since. However, only recently the field has moved towards making use of the unique properties of these cyclic molecules for applications. π-Conjugated macrocycles are now being investigated in organic solar cells, photodetectors, field-effect transistors, light-emitting diodes, and battery electrodes. They can also be used in bioimaging, as templates for the growth of carbon nanotubes, and as molecular nanoreactors.

Figure 1. (a) Reversible two-electron reduction of a π-conjugated macrocycle for charge storage in organic battery electrodes. (b) Visualization of chemical shielding tensors (VIST) helping to rationalize the optoelectronic properties.

Despite this recent interest in π-conjugated macrocycles, there are only a small number of experimental studies that investigate how the properties of π-conjugated macrocycles evolve with systematic structural changes. Recently, a team around Florian Glöcklhofer has reported such a systematic experimental study and combined it with an in-depth computational analysis. The study reveals the central role of local and global aromaticity for rationalizing the optoelectronic properties of the macrocycles. A recently developed computational method for the visualization of chemical shielding tensors (VIST) was applied to provide unique insight into local and global ring currents occurring in different planes along the macrocycles.

Figure 2. Functional group introduction and aromatic unit variation in a set of π-conjugated macrocycles.

The study makes a significant contribution to the development of structure–property relationships and molecular design guidelines and will help to understand, rationalize, and predict the properties of other π-conjugated macrocycles. Furthermore, it shows that cyclophanetetraenes, the investigated class of macrocycles, provide versatile scaffolds for applications due to their unusual properties along with their high tunability. Their remarkable optoelectronic properties, in particular their large Stokes shifts and the accessibility of a variety of charged states, were traced back to their formal ground state antiaromaticity along with high structural flexibility.

Rimmele, M.;  Nogala, W.;  Seif-Eddine, M.;  Roessler, M. M.;  Heeney, M.;  Plasser, F.; Glöcklhofer, F., Functional group introduction and aromatic unit variation in a set of π-conjugated macrocycles: revealing the central role of local and global aromaticity, Organic Chemistry Frontiers 2021, Advance Article. https://doi.org/10.1039/D1QO00901J

Author’s Biography

Florian Glöcklhofer is an Erwin Schrödinger Fellow in the Department of Chemistry at Imperial College London. He received his PhD in 2017 at TU Wien (Vienna) for developing a reaction for the conversion of quinones into cyanated aromatic compounds. His research in the field of π-conjugated organic compounds focuses on the design and synthesis of π-conjugated macrocycles for battery electrodes and organic electronics and on the development of new synthetic approaches to aromatic organic compounds.

https://www.gloecklhofer-research.com/

 

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Organic Chemistry Frontiers 2020 Best Paper Prizes

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Organic Chemistry Frontiers 2020 Best Paper Prizes

 

From this year onwards, we would like to introduce the Organic Chemistry Frontiers Best Paper prizes which recognize the most outstanding papers published in the journal. After a selection process involving the Associate Editors, Editorial and Advisory Board members, we have chosen to award not only a best paper but also a runner-up and a best review.

Best Paper

Enantioselective copper-catalysed defluorosilylation of trifluoro-methylated alkenes with silylboronates

Pan Gao, Liuzhou Gao, Longlong Xi, Zedong Zhang, Shuhua Li and Zhuangzhi Shi

Org. Chem. Front., 2020,7, 2618-2627
https://doi.org/10.1039/D0QO00773K

Corresponding authors:

Zhuangzhi Shi received his B.S. and M.S. degrees in chemistry and organic chemistry from Yangzhou University in 2005 and 2008. Then, he moved to Peking University and completed his Ph.D. in medicinal chemistry with Prof. Ning Jiao. In 2011, he joined the group of Prof. Frank Glorius at Westfalische Wilhelms-Universitat Münster (Germany), as an Alexander von Humboldt Research Fellow. In 2014, he joined the faculty at Nanjing University as a full professor. His current research efforts are focused on synthetic methodology, including the activation of inert chemical bonds, radical chemistry, boron chemistry and asymmetric catalysis.

ORCID: https://orcid.org/0000-0003-4571-4413

 

Shuhua Li is currently professor of theoretical chemistry at School of Chemistry and Chemical Engineering, Nanjing University. He received his Ph.D. in physical chemistry from Nanjing University in 1996 and then worked in Nanjing University and Texas A&M University as a postdoctoral researcher. In 2000, he joined Nanjing University as an associate professor, and was promoted as a full professor in 2002. His research interests focus on the development of novel electron correlation methods, linear scaling electronic structure algorithms, and the computational design of chemical reactions.

In 2006, he was awarded the National Science Fund for Distinguished Young Scholars. In 2008, he won the Pople Medal of Asian Pacific Association of Theoretical & Computational Chemists. In 2009, he was appointed as Changjiang Scholar Chair Professor by Chinese Ministry of Education. He received Science & Technology Award for Chinese Youth and Outstanding Young Chemist Award of Chinese Chemical Society and Royal Society of Chemistry in 2009. He was elected as the board member of the World Association of Theoretical and Computational Chemists (2014), and the board member of Asia-Pacific Association of Theoretical & Computational Chemists (2016). In 2017, he was elected as a member of the International Academy of Quantum Molecular Science. In 2020, he was elected as a fellow of Chinese Chemical Society.

ORCID: https://orcid.org/0000-0001-6756-057X

 

Best paper runner-up

Efficient labeling of organic molecules using 13C elemental carbon: universal access to 13C2-labeled synthetic building blocks, polymers and pharmaceuticals

Maria S. Ledovskaya, Vladimir V. Voronin, Konstantin S. Rodygin and Valentine P. Ananikov

Org. Chem. Front., 2020,7, 638-647
https://doi.org/10.1039/C9QO01357A

Corresponding author:

Valentine Ananikov received his Ph.D. in 1999, Habilitation in 2003, and in 2005 he became Laboratory Head of Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences. In 2008 he was elected as a Member of Russian Academy of Sciences, in 2018 elected as a Member of European Academy (Academia Europaea) and in 2019 elected as Academician of Russian Academy of Sciences.

His research has been supported by grants of the President of Russia for young scientists (2004, 2007). He was a recipient of the Russian State Prize for Outstanding Achievements in Science and Technology (2004), an Award of the Science Support Foundation (2005), a Medal of the Russian Academy of Sciences (2000), Liebig Lectureship from the German Chemical Society (2010), and Balandin Prize for Outstanding Achievements in Catalysis (2010).  He has been named Actively Cited Researcher – Russia by Thomson Reuters (2015). He was a recipient of the Organometallics Distinguished Author Award Lectureship by the American Chemical Society (2016), Hitachi High-Technologies Award in Appreciation for Novel Approaches and Outstanding Contributions to Setting New Standards for Electron Microscopy Applications in Chemistry (2016), Reaxys Award Russia (2019), Zelinsky Prize for outstanding achievements in organic chemistry (2020).

His educational activities include research laboratory at St. Petersburg State University and professorship at the Chemistry Department of Moscow State University.

His scientific interests are focused on catalysis, organic synthesis, molecular complexity and transformations. Web-site: http://AnanikovLab.ru

ORCID: https://orcid.org/0000-0002-6447-557X

 

Best Review

Recent advances in the total synthesis of cyclobutane-containing natural products

Jinshan Li, Kai Gao, Ming Bian and Hanfeng Ding

Org. Chem. Front., 2020,7, 136-154
https://doi.org/10.1039/C9QO01178A

Corresponding author:

Hanfeng Ding received his Ph.D. from Zhejiang University in 2008. From 2009 to 2011, he was a postdoctoral fellow at ASTAR, Singapore. He joined the Department of Chemistry, Zhejiang University as a faculty member in September 2011. His current research interests focus on the development of new methodologies and strategies for the total synthesis of structurally complex and biologically active natural products.

ORCID: https://orcid.org/0000-0002-1781-4604

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Recent advance in the C-F bond functionalization of trifluoromethyl-containing compounds

Organofluorine compounds play an important role in pharmaceuticals, agrochemicals, and functional materials, due to their special chemical, physical and biological properties, such as increased electronegativity, hydrophobicity, bioavailability and metabolic stability. Therefore, great efforts have recently been devoted to the development of new methods for the synthesis of fluorinated compounds. Conventional strategies mainly focus on the selective introduction of fluorine atom or fluorine-containing moiety into organic molecules. Alternatively, the development of novel synthetic methodologies via the selective activation of C-F bond is of vital importance, which could allow for the synthesis of partially fluorinated synthetic intermediates from readily available polyfluorinated starting materials. The research of C-F bond activation is the most challenging task in organic synthesis, which has recently drawn increasing attention from chemists. In this review, we mainly focus on the C-F bond activation of CF3 groups for the synthesis of fluorinated compounds as well as discussion of their mechanisms(Scheme 1).

Scheme 1 The C-F bond functionalization of trifluoromethyl-containing compounds.

Due to the electron-deficient property, α-trifluoromethylstyrenes exhibit unique reactivities in their C-F bonds activation, mainly including three kinds of reactions (SN2′-type, SNV and ipso-substitution reactions, Scheme 2).

Scheme 2 Allylic and vinylic C-F bond activation in SN2’-type, SNV and ipso-sunstitution reactions

The cleavage of C-F bond in trifluoromethylated aromatic (Scheme 3) and alkyl compounds (Scheme 4) could be achieved through using transition metal complexes, main-group Lewis acids and base-conditions. An alternative strategy mainly relied on the single-electron transfer (SET) via Low-valent metals, irradiation with visible light.

Scheme 3 Photoredox-catalyzed defluoroalkylation of ArCF3 with unactivated alkenes.

Scheme 4 Pd-catalyzed defluorination/arylation reaction of α-trifluoromethyl ketones with aryl boronic acids.

Trifluoromethyl ketones (Scheme 5) and their corresponding diazo compounds (Scheme 6) , N‑tosylhydrazones (Scheme 7) have been utilized as the coupling partners in modern synthetic organic chemistry. Recently, the C-F bond cleavage of these compounds has also been reported through transition-metal catalysts.

Scheme 5 Cu-catalyzed reaction of trifluoromethylketones with aldehydes.

Scheme 6 Cu-catalyzed gem-difluoroolefination of diazo compounds.

Scheme 7 Cu-catalyzed cross-coupling of N-tosylhydrazones with terminal alkynes.

Although great progress has been made in this rapidly developing area, these reactions still suffer from some issues of the limitation of substrates and poor regioselectivity. To overcome these central challenges, it is more important to extend the substrate scope of the existing methodologies, especial trifluoromethylated alkyl compounds. Furthermore, the robust catalytic systems will be developed for the selective activation of a single C-F bond in CF3 groups.

 Guobing Yan

Zhejiang A&F University

Guobing Yan is a Professor in college of Jiyang at Zhejiang A&F University. He obtained B.Sc. degree from Jinggangshan Normal University, his M.Sc. degree from Suzhou University, and his Ph.D. degree from Tongji University in 2010. He spent two years in 2008 and 2009 as visiting student in professor Jianbo Wang’s laboratory at Peking University. In 2013, He joined Dr. Dong’s group at the University of Texas at Austin as a visiting professor. His current research interests focus on the transition-metal-catalyzed activation of inert chemical bonds and green synthetic chemistry. He is the author of 6 patents and more than 70 articles indexed by SCI.

 

Recent Advance in the C-F bond functionalization of trifluoromethyl-containing compounds

Guobing Yan, Kaiying Qiu and Ming Guo

https://doi.org/10.1039/D1QO00037C

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C(sp3)–H functionalization with isocyanides

Isocyanides have proven to be versatile building blocks in organic synthesis and medicinal chemistry due to their synthetic possibilities capable of reacting with electrophiles, nucleophiles and radicals. Multi-component reactions involving isocyanides have been well developed with the advantages of diverse skeletons of products, functional group compatibility, high chemo-, regio and stereoselectivities, and atom economy. With the continuous research on isocyanides, C(sp3)–H functionalization with isocyanides has made significant progresses with the advancement of mechanistic studies, new techniques and novel strategies in recent years. In this review, the group of Xu and coworkers of Shanghai University of China highlights the most recent advances of isocyanide chemistry in the C(sp3)–H functionalization since 2015 by elaborating the strategies of state-of-the-art synthetic routes. The synergistic combination of the isocyanide insertion and the C(sp3)–H bond activation offers a novel and efficient route to establish complicated reactions and provides an effective strategy for the synthesis of various nitrogen- and oxygen-containing compounds.

Figure 1.C(sp3)–H functionalization with isocyanides

Bin Xu received his bachelor’s degree from Shanghai University of Science and Technology in 1992. He conducted his PhD research with Professor Shengming Ma at Shanghai Institute of Organic Chemistry and completed his degree in 2000. After a two-year postdoctoral training at National Institutes of Health (NIH) as a Visiting Fellow (Mentor: Dr Kenneth A. Jacobson), he joined VivoQuest as a staff scientist (2002–2005). He began his independent academic career at Shanghai University in the end of 2005 as a Full Professor. His current research interests span the development of new methodology for nitrogen-containing heterocycles and their biological applications.

C(sp3)–H Functionalization with Isocyanides

Org. Chem. Front., 2021, Accepted Manuscript

https://pubs.rsc.org/en/content/articlelanding/2021/qo/d1qo00153a#!divAbstract

 

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Efficient stereoselective synthesis of chiral 3,3′-dimethyl-(2,2′-bipyridine)-diol ligand and applications in Fe(II)-catalysis

Metal-assisted asymmetric catalysis has proved to be one of the most efficient strategies to obtain high stereoselectivities in organic synthesis. High levels of chiral induction in a chemical transformation, together with high turn-overs of the catalyst, arise from the best match between the transition metal and the ligand. The widespread use of N-containing ligand precursors, as enantiopure building blocks, facilitates the synthesis of a broad scope of heterocyclic ligands, such as (bis)oxazolines, salens, and NHCs. The strong chelation properties of the bipyridine core with various metal ions made chiral 2,2′-bipyridines a very promising class of ligand to be used in asymmetric catalysis.

 

A first N2O2 tetradentate 2,2′-bipyridinediol was first synthesized in the early 90’s by Bolm and efficiently used in asymmetric catalysis. Later, the stability of Lewis acid complexes with this ligand was highlighted in highly enantioselective reactions run in aqueous media, where easily hydrolysable metal salts were transformed into water-compatible metal-complexes. With the objective of optimizing chiral inductions, tremendous efforts have been invested to design new C2-symmetric 2,2′-bipyridinediol derivatives.

 

Recently, the group of Thierry Ollevier and collaborators of Laval University in Québec, Canada, have disclosed the total synthesis of 2,2′-bipyridinediol (S,S)-1 in seven steps starting from commercially available 2-bromo-5-methylpyridine, with 25% overall yield and stereoselectivities up to 99% de and >99.5% ee (Scheme). The most crucial step for high levels of stereoenrichment of the ligand was demonstrated to be the oxidative homocoupling reaction, where the physical properties of the 2,2′-bipyridine N,N′-dioxides allowed removal of undesired diastereoisomers by silica gel column chromatography. X-ray studies revealed a favored complexation of (S,S)-1 that reaches heptacoordination of FeII.

 

The potential of (S,S)-1 for asymmetric induction for the FeII-catalyzed Mukaiyama aldol and thia-Michael reactions was highlighted. An increase of the chiral induction was demonstrated using the FeII catalyst made from newly synthesized ligand vs Bolm’s ligand.

Thierry Ollevier

Laval University

Thierry Ollevier is currently Full Professor in the Department of Chemistry at Laval University in Québec, Canada. He obtained his B.Sc. (1991) and Ph.D. (1997) at the Université of Namur (Belgium), and was post doctorate fellow at the Université catholique de Louvain (Belgium), under István E. Markó (1997), NATO postdoctorate fellow at Stanford University under Barry M. Trost (1998–2000), then post doctorate fellow at the Université de Montréal under André B. Charette (2000–2001). Current research in his group aims at designing novel catalysts, developing catalytic reactions and applying these methods to chemical synthesis. He is active in the areas of iron catalysis, diazo chemistry, asymmetric catalysis, and synthetic green chemistry. He is the author of more than 70 articles indexed by SCI and cited more than 2000 times.

http://www2.chm.ulaval.ca/tollevier/

 

Efficient stereoselective synthesis of chiral 3,3′-dimethyl-(2,2′-bipyridine)-diol ligand and applications in FeII-catalysis 

S. Lauzon, L. Caron and T. Ollevier, Organic Chemistry Frontiers2021.

https://doi.org/10.1039/D1QO00188D 

 

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Hole-mediated PhotoRedox Catalysis: Tris(p-substituted)biarylaminium Radical Cations as Tunable, Precomplexing and Potent Photooxidants

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Hole-mediated PhotoRedox Catalysis: Tris(p-substituted)biarylaminium Radical Cations as Tunable, Precomplexing and Potent Photooxidants.

Processes involving visible light photoinduced electron transfer (PET) are at the forefront of contemporary organic synthesis and allow access to reactive intermediates unavailable from conventional chemical reactivity. The selective delivery of photon energy to visible light-active photocatalysts which engage visible light-inactive molecules in PET is now an established synthetic technology known as PhotoRedox Catalysis (PRC). PRC is broadly-applicable, selective, proceeds under exceedingly mild conditions and is changing the way we do organic synthesis. However, PRC suffers some key limitations. Firstly, excess sacrificial chemical oxidants (O2) or reductants (trialkylamines) are needed to turn over the ‘spent’ photocatalyst which can (or whose by-products, such as peroxides, can) interfere with subsequent chemical processes and need separation from desired products. Secondly, the scope of redox processes is fundamentally restricted by the energy of visible light photons (400-700 nm; 1.8-3.1 eV) and not all of this photon energy provided to the photocatalyst can be harnessed synthetically. Although high energy visible photons (400-450 nm) can temporarily populate excited states higher than the first excited state, Kasha’s rule dictates that relaxation to the first excited state is faster than typical diffusion-controlled photochemistry. This limits the applications of PRC in challenging redox processes.

Nature overcomes photon energy limitations by accumulating multiple photons for challenging chemical processes; several red photons are required for transfer of electrons to CO2 in biological photosynthesis. With some exceptions, harnessing of multiple photon energies in PRC to access super-oxidizing or super-reducing excited states has largely eluded researchers. The fusion of photochemistry and electrochemistry provides an innovative solution to all issues above. Electroactivation of a catalyst to a colored radical ion, followed by its photoexcitation, exceeds the accessible excited state redox potentials of PRC alone (>3.0 eV). Some examples of this concept, coined ‘electrochemically-mediated PhotoRedox Catalysis’ (e-PRC), have emerged in the literature. A question that has eluded researchers is how excited radical ions (typically doublet states) could ever engage in photochemistry, given their typical picosecond lifetimes forbid diffusion. Moreover, while catalyst ‘tunability’ is well established in PRC, it is yet to be established in synthetic photoelectrochemistry.

 

Figure 1. Triarylamines (TAAs) as tunable e-PRCats developed by the Barham grou.; A. SET activation of challenging arenes and C-N bond formation with N-heterocycles. B. Experimental setup showing electroactivation of TAAs and photoexcitation of TAA.+s in a divided cell.

Recently, the group of Joshua Philip Barham and collaborators at Universität Regensburg, Technische Universität München and the Central European Institute of Technology introduced triarylamines (TAA) as a new family of tunable electroactivated photoredox catalyst (e-PRCat). The group demonstrated that facile tuning of the e-PRCat accessed record-breaking excited state potentials of Epox = +4.4 V vs SCE. This allowed PET super-oxidations of very challenging arenes, like polychloroarenes, polyfluoroarenes and trifluorotoluene, resulting overall in C-N bond formation with pyrazole partners. Catalyst power could be tuned down to access moderately challenging arenes (alkylbenzenes, benzene) with higher selectivity. Of key importance is the discovery of p-stacking dispersion precomplexation between the radical ion e-PRCat (TAA.+) and substrate to rationalize, for the first time, the photochemistry of excited state radical ions. The study sets the scene for dispersive precomplexation as a novel control element in photochemistry, which allowed the group to:

1) circumvent of ultrashort lifetimes of radical ion excited states (*TAA.+, t < 10 ps) for use in PET,

2) override Kasha’s rule and access to higher order excited states, to harness the full power of the visible photon’s energy (Epox *TAA.+ > 4.0 V vs. SCE),

3) overturn conventional thermodynamic redox selectivity (1,4- > 1,2-disubstituted arenes) by steric/electronic factors involved in precomplexation (1,2- > 1,4-disubstituted arenes).

Figure 2. Proposed mechanism of hole-mediated photoredox catalytic super-oxidation of arenes, involving dispersive precomplexation via a T-p interaction, supported by DFT calculations and changes in EPR spectroscopy of the TAA.+ in the presence of arene substrates following a shift in spin density (increasing triplet representation of the signal).

 

Joshua Philip Barham

Universität Regensburg

Joshua Philip Barham is a Sofja Kovalevskaja Group Leader in the Faculty of Chemistry and Pharmacy at the University of Regensburg (Germany), where he investigates photo-, electro-, photoelectro- and flow chemistry as enabling technologies in organic synthesis. He received his industry-based Ph.D in Chemistry in 2017 under the supervision of Prof. John Murphy at the University of Strathclyde (U.K.) and Dr. Matthew John at GlaxoSmithKline (U.K.). His postdoctoral studies with Prof. Yasuo Norikane and Prof. Yoshitaka Hamashima at the National Institute of Advanced Industrial Science and Technology and the University of Shizuoka (Japan) specialized in photoredox catalysis and microwave flow chemistry. In addition to his authorship of 20 articles indexed by SCI which have been cited ~450 times, he has authored a book chapter, a patent, an industrial press release and various blogs/webinars. For a complete list of publications, see: http://www-oc.chemie.uni-regensburg.de/barham/page_417_en.php

https://scholar.google.co.uk/citations?user=fBgXhboAAAAJ&hl=en

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Article Highlight: Photocatalytic intermolecular anti-Markovnikov hydroamination of unactivated alkenes with N-hydroxyphthalimide

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Photocatalytic intermolecular anti-Markovnikov hydroamination of unactivated alkenes with N-hydroxyphthalimide

 

Intermolecular olefin hydroamination is an efficient strategy to form C-N bonds and then construct high-value amines. Traditional olefin hydroamination methods mainly provide Markovnikov products. Thus, it is interesting and challenging to realize anti-Markovnikov olefin hydroamination.

In 2019, Yang’s group reported a visible-light-induced strategy to achieve N-OH bond cleavage of strained cyclobutanone oxime, which is able to activate the N-O bond directly to construct various cyano/gemdifluoroalkene-containing scaffolds via synergistic effects between visible light and phosphoranyl radical cation (Org. Lett. 2019, 21, 2658-2662). Recently, this group designed a visible-light photoredox-catalysed hydroamination of unactivated alkenes using N-hydroxyphthalimide (NHPI) to generate anti-Markovnikov product exclusively based on previous work (Scheme 1). The high versatility and mild conditions of this strategy allow a facile access to various amines using cheap and easily available reagents.

Scheme 1 Photocatalytic intermolecular anti-Markovnikov hydroamination of unactivated alkenes with N-hydroxyphthalimide

Cyclohexene 1a and NHPI were chosen as model substrates. Optimization of reaction conditions shows that the highest yield (82%) could be obtained when using [Ir(dFCF3ppy)2dtbbpy]PF6 and P(OEt)3 as catalyst and MeCN as solvent at room temperature in 24 hours. A wide variety of unactivated alkenes could be tolerated, including cyclic and acyclic aliphatic olefins. Moreover, aliphatic olefins substituted with halogen or trimethylsilyl group could also provide the corresponding products in moderate yields (Table 2).

 

Table 2 Substrate Scope of Unactivated Olefinsa

aConditions: olefin 1 (0.6 mmol, 3.0 equiv.), N‑hydroxyphthalimide (0.2 mmol, 1.0 equiv.), P(OEt)3(0.3 mmol, 1.5 equiv.), [Ir(dFCF3ppy)2dtbbpy]PF6 (2 mol%), MeCN (4 mL), 30 w blue LED, rt, argon atmosphere, 24 h, isolated yield.

Scheme 2. Control experiments

To gain mechanistic insights into this reaction, several control experiments were then carried out. Product formation was inhibited, when radical trapping agents such as 2,2,6,6-tetramethyl-1-piperdinyloxy (TEMPO) or benzoyl peroxide(BPO) were added under the standard reaction conditions, suggesting a radical process was involved possibly. On/off experiments demonstrate the corresponding product is formed upon irradiation, as well as in the dark, which supports a chain-propagation-type radical reaction (Scheme 2).

Scheme 3. potential energy surface of the plausible reaction pathway.

 

Furthermore, DFT calculations were performed to understand the catalytic mechanism.Initially, the [Ir(III)]isexcited to *[Ir(III)] under the irradiation of visible light. Then, NHPI and P(OEt)3are able to oxidatively quench *[Ir(III)] via a PCET-mediated activation of O-H bond to afford the corresponding PINO radical. The key PINO radical undergoes a radical addition with P(OEt)3 to deliver phosphoranyl radical I via TS1. Subsequently, N-centred radical intermediate II is formed through β-scission fragmentation of radical I, releasing triethyl phosphate. This step is calculated to possess a Gibbs free energy barrier of 7.8 kcal/mol and is highly irreversible with a driving force as large as 49.5 kcal/mol. In the presence of alkene, a radical addition occurs facilely to generate radical intermediate III. Finally, this resulting radical intermediate III promotes a hydrogen atom transfer from NHPI to deliver the desired product 3a and simultaneously regenerate the PINO radical, which would react with P(OEt)3 to initiate another radical reaction. Notably, this chain-propagation-type mechanism agrees well with our control experiments and Schmidt’s results.
In summary, this group successfully developed a visible-light photoredox-catalysed hydroamination of alkenes using N-hydroxyphthalimide (NHPI) with exclusive anti-Markovnikov selectivity. High synthetic efficiency and mild reaction conditions would endow this protocol with potentials and flexibility in building various aliphatic amines.

Corresponding author

Professor Hua Yang at College of Chemistry and Chemical Engineering Central South University has a great interest in organic synthesis, asymmetric catalysis, visible-light catalysis and total synthesis of chiral drug molecules. Professor Yang developed an excellent organic catalyst-“Hua Cat”. And this patented reagent was commercialized by Sigma-Aldrich, and has been widely applied in asymmetric synthesis.

Hao-Yue Xiang, is an associate professor at College of Chemistry and Chemical Engineering, Central South University. Dr. Xiang received his PhD degree from Shanghai Institute of Materia Medica, Chinese Academy of Sciences and has made great progresses in the construction of heterocyclic compound library and the discovery of lead compounds. Dr Xiang’s current research focus is on fluorine chemistry, boron chemistry and radical chemistry.

Dr Kai Chen, at College of Chemistry and Chemical Engineering, Central South University.mainly work in computational organic chemistry, designof autocatalytic system, and computer-aided drug design. Chen received his PhD at Peking University in 2014, and then moved to South China University of Technology. Since 2019, Chen worked at Central South University.

Peng-Ju Xia, is lecturer of School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University.Xia mainly work inresearch field ofphotocatalytic/electrochemical organic catalysis and and 1, 3-dipole cyclization.

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Outstanding Reviewers for Organic Chemistry Frontiers in 2019

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We would like to highlight the Outstanding Reviewers for Organic Chemistry Frontiers in 2019, as selected by the editorial team, for their significant contribution to the journal. The reviewers have been chosen based on the number, timeliness and quality of the reports completed over the last 12 months.

We would like to say a big thank you to those individuals listed here as well as to all of the reviewers that have supported the journal. Each Outstanding Reviewer will receive a certificate to give recognition for their significant contribution.

Dr Pablo Ballester, Institute of Chemical Research of Catalonia (ICIQ), ORCID: 0000-0001-8377-6610

Dr Ying-Chun Chen, Sichuan University, ORCID: 0000-0003-1902-0979

Prof Xuefeng Jiang East China Normal University, ORCID: 0000-0002-1849-6572

Dr Shukkoor Muhammed Kondengaden, Georgia State University

Prof Zhan Lu, Zhejiang Universitry, ORCID: 0000-0002-3069-079X

Dr Feng Shi, Jiangsu Normal University, ORCID: 0000-0003-3922-0708

Dr Qiuling Song, Huaqiao Univeristy, ORCID: 0000-0002-9836-8860

Dr Jie Wu, Fudan University, ORCID: 0000-0002-0967-6360

Dr Da-Gang Yu, Sichuan University, ORCID: 0000-0001-5888-1494

Dr Yonghui Zhang, Huazhong University of Science and Technology, ORCID: 0000-0002-7222-2142

We would also like to thank the Organic Chemistry Frontiers board and the organic chemistry community for their continued support of the journal, as authors, reviewers and readers.

 

If you would like to become a reviewer for our journal, just email us with details of your research interests and an up-to-date CV or résumé.  You can find more details in our author and reviewer resource centre

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Congratulations to our highly cited board members!

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We are proud to announce that 5 of Organic Chemistry Frontiers Board members are recognized in Clarivate Analytics list of Highly Cited Researchers for 2019, ranking them among the top 1% most cited for their subject field and publication year.

The board members are:

Editorial Board

Frank Würthner, University of Würzburg, Germany

Advisory Board

Matthias Beller, University of Rostock, Germany
Frank Glorius, Westfälische Wilhelms-Universität Münster, Germany
Lutz Ackermann, Georg-August-Universitat Gottingen, Germany
Chen-Ho Tung, Technical Institute of Physics and Chemistry, China

 

Below are a few of our picks from their publications in Organic Chemistry Frontiers.
Access is free to these highlighted papers until 31 Jan 2020!

Guest-mediated chirality transfer in the host–guest complexes of an atropisomeric perylene bisimide cyclophane host
Meike Sapotta, Peter Spenst, Chantu R. Saha-Möllera and Frank Würthner*
Org. Chem. Front., 2019,6, 892-899
http://dx.doi.org/10.1039/C9QO00172G

Progress in the synthesis of perylene bisimide dyes
Agnieszka Nowak-Król and Frank Würthner*
Org. Chem. Front., 2019,6, 1272-1318
http://dx.doi.org/10.1039/C8QO01368C

Water-soluble naphthalene diimides: synthesis, optical properties, and colorimetric detection of biogenic amines
Annike Weißenstein, Vincenzo Grande, Chantu R. Saha-Möllera and Frank Würthner*
Org. Chem. Front., 2018,5, 2641-2651
http://dx.doi.org/10.1039/C8QO00611C

Decarboxylative sulfenylation of amino acids via metallaphotoredox catalysis
Lidan Wei, Chengjuan Wu, Chen-Ho Tung, Wenguang Wang* and Zhenghu Xu*
Org. Chem. Front., 2019,6, 3224-3227
http://dx.doi.org/10.1039/C9QO00817A

Scandium-catalyzed electrophilic alkene difunctionalization: regioselective synthesis of thiosulfone derivatives
Shuai Huang, Haoyu Li, Tian Xie, Fang Wei*, Chen-Ho Tung and Zhenghu Xu*
Org. Chem. Front., 2019,6, 1663-1666
http://dx.doi.org/10.1039/C9QO00138G

Cobalt-catalyzed radical cyclization of isocyanides forming phenanthridine derivatives
Xiangyu Liu, Chengjuan Wu*, Jing Zhang, Yihan Shi, Shengnan Zhang, Yan Geng, Chen-Ho Tung and Wenguang Wang*
Org. Chem. Front., 2018,5, 2997-3002
http://dx.doi.org/10.1039/C8QO00887F

Recent advances in positional-selective alkenylations: removable guidance for twofold C–H activation
Wenbo Ma*, Parthasarathy Gandeepan*, Jie Lid and Lutz Ackermann*
Org. Chem. Front., 2017,4, 1435-1467
http://dx.doi.org/10.1039/C7QO00134G

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Jennifer Schomaker joins OCF as Associate Editor

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Organic Chemistry Frontiers is delighted to welcome Professor Jennifer Schomaker (University of Wisconsin-Madison, USA) as Associate Editor for the journal.

Biography

Jennifer Schomaker began her research career at Dow Chemical in Organic Chemicals and Polymers, later moving to Agricultural Chemicals Process Research, where she participated in route selection and scale-up campaigns for two new herbicides. After 7 years in industry, she obtained her Ph.D. with Professor Babak Borhan at Michigan State University in 2006 before moving to UC-Berkeley as an NIH postdoctoral fellow under Professors Robert G. Bergman and F. Dean Toste. She joined the University of Wisconsin-Madison in 2009, where she is a full professor.

 

 

 

 

Research Highlights

Her research focuses on new methodologies for preparing stereochemically complex, densely functionalized amines, catalyst-controlled, tunable chemo- and site-selective C-H functionalizations, uncovering new reactivities catalyzed by first-row transition metals, total synthesis of bioactive natural and unnatural products, and development of new bioorthogonal labeling reagents.

Check some of her publications at Royal Society of Chemistry:

Regioselective differentiation of vicinal methylene C–H bonds enabled by silver-catalysed nitrene transfer

Ryan J. Scamp, Bradley Scheffer and Jennifer M. Schomaker

Chem. Commun., 2019,55, 7362-7365

Tunable differentiation of tertiary C–H bonds in intramolecular transition metal-catalyzed nitrene transfer reactions

Joshua R. Corbin and Jennifer M. Schomaker

Chem. Commun., 2017,53, 4346-4349

 

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