Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• chlorobenzene at 293 K in the absence of light, air, and water. In each case the reaction is apparently first order in dopant, consistent with the rate law: previously demonstrated for 1bH and VI [9]. The rate constants, k, obtained assuming this rate law are shown in Table 2 (the value for 3b being similar to

• strongly bound dimers. Figure 8b compares the evolution of one of the distinctive VII •– absorptions when doping VII with excess 12 derivatives in chlorobenzene at 293 K in the absence of light, air, and water. In the case of the Y = 4-dimethylaminophenyl dimers 1b2 and 1g2, the VII•– absorption grows in

A series of perylene diimide cathode interlayer materials for green solvent processing in conventional organic photovoltaics

• Kathryn M. Wolfe,
• Shahidul Alam,
• Eva German,
• Fahad N. Alduayji,
• Maryam Alqurashi,
• Frédéric Laquai and
• Gregory C. Welch

Beilstein J. Org. Chem. 2023, 19, 1620–1629, doi:10.3762/bjoc.19.119

• Organic photovoltaic (OPV) devices for energy harvesting or light recycling are of interest due to their low cost, fabrication via layer-by-layer printing, flexibility, and low carbon footprint [1][2]. Due to the processability of organic materials used in OPVs, the large-scale manufacturing of such

• the light from those measured in the dark using the formula Jph = JL – JD, where JL denotes the current density measured in the light, and JD represents the current density measured in the dark. The voltage (V0) that prevails when Jph is equal to zero was used in the calculation for Veff, and the

• (TPC) and light intensity-dependent IV (LID-IV) measurements. TPC measurements were performed to verify charge carrier transport properties, and current decay was monitored after 500 μs pulse. The normalized TPC data for all the devices is shown in Supporting Information File 1, Figure S34a. The

Synthesis of 7-azabicyclo[4.3.1]decane ring systems from tricarbonyl(tropone)iron via intramolecular Heck reactions

• Aaron H. Shoemaker,
• Elizabeth A. Foker,
• Elena P. Uttaro,
• Sarah K. Beitel and
• Daniel R. Griffith

Beilstein J. Org. Chem. 2023, 19, 1615–1619, doi:10.3762/bjoc.19.118

• secondary amine according to our previously described, solvent-free protocol [12][13]. The resulting iron complex 6 was demetallated upon irradiation with UV light [14] to give the deconjugated olefin 7. We then hoped to forge the desired bicycle 8 (Table 1) via a 6-exo-trig Heck cyclization, drawing on the

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• photoredox catalyst mediated by light to overcome the challenge of metal contamination in the precipitated polymers [58]. After the ATRP reaction, a reactive chain end retains as a stable alkyl halide moiety. Therefore, ATRP is particularly suitable for the synthesis of polymers with complex architectures

• has been used to cure a liquid isoprene polymer in precise digital light processing 3D printing [105]. Recently, Kanbayashi et al. reported that thiol–ene chemistry would not cause racemization of an asymmetric center linked to a pendant vinyl group, which can be particularly valuable for

• crosslinking of polymers. Polymeric materials may become brittle or colored after being exposed to sunlight for a long time, which was called 'photo-ageing' [134]. In fact, the light sensitivity of many polymers results from some impurities or additives remaining in polymer materials, which can form radical

C–H bond functionalization: recent discoveries and future directions

• Indranil Chatterjee

Beilstein J. Org. Chem. 2023, 19, 1568–1569, doi:10.3762/bjoc.19.114

• feedstocks, the introduction of functionality at specific positions of molecules without requiring any prefunctionalized precursors, and the conversion of light alkanes to higher-value analogues [1][2]. The nonnecessity of prefunctionalization provides a step-economic alternative to classical reactions as

Functions of enzyme domains in 2-methylisoborneol biosynthesis and enzymatic synthesis of non-natural analogs

• Binbin Gu,
• Lin-Fu Liang and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1452–1459, doi:10.3762/bjoc.19.104

• were recorded on a Modular Compact Polarimeter MCP 100 (Anton Paar, Graz, Austria). The temperature setting was 20 °C, the wavelength of the light used was 589 nm (sodium D line), the path-length was 10 cm, and compound concentrations c are given in g 100 mL−1. Synthesis of 2-Me-GPP To an Et2O (10 mL

Consecutive four-component synthesis of trisubstituted 3-iodoindoles by an alkynylation–cyclization–iodination–alkylation sequence

• Nadia Ledermann,
• Alae-Eddine Moubsit and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2023, 19, 1379–1385, doi:10.3762/bjoc.19.99

• isolation) accounts for an average yield of 55–90% per bond-forming step which can be considered to be relative efficient, also because only a single terminal purification step is required. However, noteworthy, the 3-iodoindoles are sensitive to light and prolonged storage at room temperature, even under

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

• ., Zibo 256401, China 10.3762/bjoc.19.98 Abstract A visible-light-induced nickel-catalyzed cross coupling of alkyl carboxylic acids with N-trifluoroethoxyphthalimide is described. Under purple light irradiation, an α-hydroxytrifluoroethyl radical generated from a photoactive electron donor–acceptor

• direct conversion of carboxylic acids to ketones is an important chemical transformation [31][32][33][34][35][36][37][38]. However, to the best of our knowledge, this protocol has not been used for the synthesis of fluoroalkylated ketones so far. Very recently, we have developed a visible-light-induced

• might be feasible. Herein, we disclose a visible-light-induced nickel-catalyzed cross-coupling of alkyl carboxylic acids with N-trifluoroethoxyphthalimide to deliver trifluoromethyl aliphatic acyloins under mild conditions (Scheme 1d). Furthermore, this platform bypasses the need for exogenous

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• Abstract Organic thermally activated delayed fluorescence (TADF) materials have been widely investigated due to their impressive electronic properties and applied potential for the third generation of organic light-emitting diodes (OLED). We present organic TADF material (4BGIPN) based on the strained

• fluorescence [1][2][3]. Organic TADF emitters have gained substantial attention in recent years for their prospective application in organic light-emitting diodes (OLEDs), photocatalysis, bioimaging, and sensors [4][5][6]. The ability to harvest both singlet and triplet excitons enable organic TADF emitters to

• LUMO energy levels, along with multiple electron-withdrawing aza-nitrogen atoms in the structure of 4BGIPN, suggests its potential suitability as an electron transport layer in OLED (organic light-emitting diode) devices. Variable temperature photoluminescence studies revealed that 4BGIPN corresponds

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

• into a carbon-centered radical B which then combines with 2-methylpyridine to obtain radical intermediate C. Oxidation of intermediate C by radical A then furnishes the product. Photocatalyzed CDC reactions In recent years, visible-light-driven photocatalytic processes have been considered influential

• methodologies involving ether α-C(sp3)–H and aromatic C(sp2)–H bonds were investigated and these are shown in Scheme 43. Shah et al. reported a catalyst-free CDC method using only 2 equivalents of K2S2O8 in H2O under irradiation with a 27 W CFL (Scheme 43a) [123]. In this reaction, both water and the light

• 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

Radical ligand transfer: a general strategy for radical functionalization

• David T. Nemoto Jr,
• Kang-Jie Bian,
• Shih-Chieh Kao and
• Julian G. West

Beilstein J. Org. Chem. 2023, 19, 1225–1233, doi:10.3762/bjoc.19.90

• addition to alkenes and radical decarboxylation, with many of these being driven by light energy. RLT in alkene functionalization Outside of the realm of C–H activation, RLT has been leveraged to afford complex medicinal scaffolds in alkene difunctionalization. A recent example can be found in the merger

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• study is potentially useful for the development of highly conjugated π-electron rich porphyrinoids with improved light harvesting properties. Experimental Materials and instrumentation methods All reagents and solvents used in this study were purchased from Sigma-Aldrich (Merck) and were used as

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• been used in artificial photosynthesis research to model different key photosynthesis processes. In plants, photosynthesis is a complex process where light-harvesting reactions are carried out in two photosystems to split water and recycle NADH and ADP. NADPH and ATP are then consumed in the Calvin

• low absorption in the visible region to prevent side reactions and allow the photosensitizer to absorb as much light as possible. The oxidation potential of the sacrificial electron donor must be less positive than the reduction potential of the excited or oxidized photosensitizer for quenching or

• or oxidized photosensitizer is the driving force for the electron transfer and photosensitizer regeneration. This driving force determines the rate of electron transfer from the electron donor to the photosensitizer which regulates the amount of photosensitizer available to harvest light energy and

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• -holes. Halogen bonding and σ-holes have been encountered in numerous monovalent and hypervalent iodine-containing compounds, and in 2022 σ-holes were computationally confirmed and quantified in the iodonium ylide subset of hypervalent iodine compounds. In light of this new discovery, this article

• events. Xuan, Li and co-workers further investigated the coupling between iodonium ylides and tertiary amines, and showed that this thermal reaction could instead be initiated by blue light photocatalysis (Scheme 7) [124]. Therein, they investigated the iodoarene motif of the ylide, and while ylide 31

• ). Control experiments showed that the reaction failed in the dark at room temperature, and they concluded that blue light activation of the initially-formed EDA complex (analogous to 36) promoted the onset of SET events. As this latter protocol also required two equivalents of ylide 39, the authors proposed

New one-pot synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones based on 5-aminopyrazoles and azlactones

• Vladislav Yu. Shuvalov,
• Ekaterina Yu. Vlasova,
• Tatyana Yu. Zheleznova and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2023, 19, 1155–1160, doi:10.3762/bjoc.19.83

• when irradiated with UV light. Keywords: 5-aminopyrazole; azlactone; elimination; fluorescence; one-pot synthesis; pyrazolo[3,4-b]pyridin-6-one; Introduction The pyrazolo[3,4-b]pyridine scaffold is present in many biologically active compounds [1][2][3][4][5][6][7][8][9][10][11][12]. Among them, 4

• -trimethoxyphenyl- (4e), 2-furyl- (4h) and 2-thienyl- (4i), the product yields are reduced to 55–60% (Scheme 2). All the compounds obtained are colorless crystalline substances. When dissolved, they produce colorless solutions exhibiting distinct fluorescent properties with blue emission when exposed to UV light

• UV light, are used in forensics, in protection against forgery of banknotes, securities, and other important documents [34]. Conclusion In summary, we developed a simple one-pot synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones, based on the solvent-free reaction of the available starting compounds 5

Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light

• Damiano Diprima,
• Hannes Gemoets,
• Stefano Bonciolini and
• Koen Van Aken

Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82

• byproducts, and increased efficiency in industrial processes. As such, this field of research is of great importance and interest to both academia and industry. This work showcases a sustainable and catalyst-free oxidation method for heteroatoms (e.g., S, P, and Se) using only air, water and light. An

• electrochemistry, the electron transfer occurs locally at the surface of the physical electrodes (typically located at a distance in the range of 200 μm to 2 cm) on which a potential is induced by an external potentiostat (Scheme 2). While for photoredox chemistry, the light-activated semiconductor catalyst

• , the optimized conditions from our group [34] from a previously reported electrochemical procedure [35] were employed (i.e., solvent CH3CN/H2O 80:20, 0.1 M n-Bu4Br, inert argon atmosphere). As for the photoredox catalyst we used the “first choice” TiO2 and irradiation with 365 nm LED light. In the

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

• generation of reactive intermediates for both oxidative and reductive processes via photon activation of a catalyst. Although this represents a significant step towards chemoselective and, more generally, sustainable chemistry, its efficacy is limited by the energy of visible light photons. Nowadays

• conditions are available via PRC (vide infra). However, even if PRC provides elegant methods to circumvent these issues, it comes with its own set of limitations. In particular, the accessible energy for photocatalytically-driven transformations is generally limited by the energy of a single visible light

• remain inert to direct photoredox activation powered by visible light [12]. Irradiation with UV photons that intrinsically possess higher energy, however, is generally unfavorable due to the high expense and thermal footprint of the reactors. Although most organic molecules directly absorb photons in the

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• ; electron donor; intersystem crossing; TADF; triplet state; Introduction Thermally activated delayed fluorescence (TADF) compounds are promising emitters to be used in organic light-emitting diodes (OLED) [1][2][3][4][5][6][7][8][9][10][11][12]. These emitters have the advantage of low cost and high

• continuous rotation to avoid damage. The pump-probe delay was introduced by sending the portion of the fundamental beam used for white light generation through a motorized translator. After focusing and overlapping the pump and probe beams at the sample position, the probe beam was directed through a

Linker, loading, and reaction scale influence automated glycan assembly

• Marlene C. S. Dal Colle,
• Manuel G. Ricardo,
• Nives Hribernik,
• José Danglad-Flores,
• Peter H. Seeberger and
• Martina Delbianco

Beilstein J. Org. Chem. 2023, 19, 1015–1020, doi:10.3762/bjoc.19.77

• light (λ = 360 nm), L1 releases the glycan equipped with an aminoalkyl spacer at the reducing end, whereas L2 affords the free reducing sugar (α/β mixture). Previous data suggested that UV cleavage of L1 and L2 was equally efficient, permitting the isolation of a tetramannoside in around 60% yield [3

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• are desired in light of growing environmental concerns. As a result, this review will explain various green chemistry approaches to synthesize N-substituted pyrroles. Although, Wynn [54] summarized several Clauson–Kaas protocols for the synthesis of N-substituted pyrrole derivatives. However, a

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

• photocatalyst. Keywords: decarboxylative cyclization; DMAT; ergot alkaloids; photoredox catalysis; radicals; Introduction Visible-light photoredox catalysis is rapidly changing the way organic chemists approach the design and synthesis of molecules by offering new synthetic disconnection opportunities that

• of all ergot alkaloids, specifically the decarboxylative cyclization of DMAT, is still a puzzle even though a radical mechanism has been proposed (Figure 1a) [72][73]. Results and Discussion Herein, we propose that visible light irradiation of the cationic iridium photocatalyst Ir[dF(CF3)ppy]2(dtbbpy

• 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

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• ], Liu [35], and Yang [36] achieved similar transformations through visible-light photocatalysis. In addition, Guo [37][38] improved the protocol by using low-cost nickel and iron catalysts. However, most of these advancements mainly relied on the excellent redox potential manipulation of cyclic oxime

Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• Adrian Saura-Sanmartin Departamento de Química Orgánica, Facultad de Química, Universidad de Murcia, 30100 Murcia, Spain 10.3762/bjoc.19.64 Abstract Light-responsive rotaxane-based solid-state materials are ideal scaffolds in order to develop smart materials due to the properties provided by the

• counterparts and/or macroscopic motion of the interlocked materials are achieved. Although further development is needed, these materials are envisioned as privileged scaffolds which will be used for different advanced applications in the area of molecular machinery. Keywords: light irradiation; light

• -responsive materials; mechanical bond; mechanically interlocked materials; rotaxanes; Introduction Light turns out to be a suitable and tailorable stimulus in order to develop materials showing improved functionalities, such as those of smart materials [1][2][3][4][5]. The characteristics of light which

Non-peptide compounds from Kronopolites svenhedini (Verhoeff) and their antitumor and iNOS inhibitory activities

• Yuan-Nan Yuan,
• Jin-Qiang Li,
• Hong-Bin Fang,
• Shao-Jun Xing,
• Yong-Ming Yan and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 789–799, doi:10.3762/bjoc.19.59

• experimental and ECD spectra (Figure 3 and Figure S26 in Supporting Information File 1). Consequently, the structure of 4 is defined and named 5-O-methyldaphnegiralin C1. Compound 7, a light yellow gum, has the molecular formula C16H28O3 (three degrees of unsaturation) as determined by its HRESIMS [M + H]+ ion

• at C-3 remains undetermined due to its long carbon chain. As a consequence, the structure of compound 7, named kronoponoid A, was determined to be as showed in Figure 1. Compound 8, a light yellow gum, possesses the molecular formula C17H30O3 (three degrees of unsaturation) deduced from its HRESIMS

• /z): [M + H]+ calcd for C21H25O5, 357.1697; found, 357.1680; 1H and 13C NMR data, see Table 3. Kronoponoid A (7): light yellow gum; [α]D25 +7.50 (c 0.40, MeOH); UV (MeOH) λmax, nm (log ε): 202 (3.68); HRESIMS (m/z): [M + H]+ calcd for C16H29O3, 269.2111; found, 269.2116 ; 1H and 13C NMR data, see

Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Mikhail E. Minyaev and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58

• proposed. Keywords: allomaltol; dihydrobenzo[h]pyrano[2,3-f]quinazolines; 6π-electrocyclization; photocyclization; pyrimidines; Introduction Photochemical processes involve absorption of UV light leading to the generation of molecules in the excited state and subsequent chemical transformations [1][2

• bridge fragments. At the same time, it is obvious that the ring size can significantly influence the photochemical properties. In this regard, it seemed interesting to obtain terarylenes with a six-membered bridge and to study their behavior under the action of UV light. Continuing our research in the