Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• stoichiometric electron donors, the presence of a TM catalyst, the formation of a charge-transfer complex, and the overall reaction conditions. While we hope that this discussion will spur the continued development of NHPI esters in complexity-generating transformations, it is not comprehensive, and we refer

• -derived NHPI esters has found application in the total synthesis of natural products, including the plant metabolite denobilone A and the highly oxidized dibenzocyclooctadiene lignans heteroclitin J and kadsulignan E [55]. Activation via charge-transfer complex formation Under conditions where oxidative

• ) for π-stacking between the furan and phthalimide rings, before EnT from *IrIII leads to the formation of an excited charge-transfer complex 47. This species would undergo intramolecular electron transfer (IET) giving rise to intermediate 48, which upon fragmentation would form radical 49

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• charge-transfer complex AB. Subsequently, this complex forms a zwitterion intermediate (C1), followed by the formation of a cyclobutene intermediate (C2), ultimately forming the product P. However, the researchers strongly advocated for an alternative pathway, which entails the formation of a complex

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• EDA charge transfer complex because there was no obvious EDA charge transfer band in the UV–vis spectra (Figure 2). Their indole substrate was more electron-rich in structure. The quantum yield was measured to investigate whether there was a radical chain process or not. The procedure was following a

Recent advancements in iodide/phosphine-mediated photoredox radical reactions

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

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

• ], it was proposed that the decarboxylative cascade cyclization reaction proceeded through the formation of a charge-transfer complex (CTC) II involving PPh3, NaI, and NHP ester 3 (Scheme 20). Upon photofragmentation of the CTC complex II, two important intermediates were generated: an alkyl radical A

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

• oxidation products are positively charged. This will stabilize the charge-transfer complex formed during quenching and combined with fast electron transfer will likely increase the rate of recombination and decrease their effectiveness as donors. The oxidation potentials of the viologens (Figure 4) are

• during carbon dioxide reduction to be reoxidized. Because viologens are positively charged and are reduced to neutral compounds, it is likely that the resulting charge-transfer complex will have a higher cage escape yield than a complex where the oxidized donor has a positive charge. However, in some

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

• acceptor [61]. Beyond simply considering the strength of these bonds, other characteristics of this interaction should directly impact the outcomes of the reactions that they undergo. For instance, Mulliken’s initial description of an intermolecular halogen bond was of a charge transfer complex (also known

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

• Asha Budakoti,
• Pradip Kumar Mondal,
• Prachi Verma and
• Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

• DDQ and the subsequent abstraction of hydride from the benzylic or allylic position generated a charge-transfer complex 298. The complex 298 formed a tin-containing ate oxocarbenium ion complex 299 with SnBr4, and then rapid C–C bond formation took place to generate the cyclic intermediate 300. The

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

• decomposes into ketone or aldehyde products (Scheme 9). However, in the absence of light or oxygen, disulfide could not catalyze the oxidative cleavage of olefins. It was proposed that disulfide and the olefin might be able to form a charge-transfer complex, which may rationalize the unconventional homolysis

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• radical mechanism in which the iminoxyl radical is generated from the oxime anion under the action of perfluorobutyl iodide through the formation of an EDA complex (electron donor–acceptor complex, which is also called charge-transfer complex). The perfluorobutyl radical formed at this step served for the

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• chemical transformations come from this process, whose crucial step involves the formation of a charge-transfer complex between singlet oxygen and the amine. Subsequently, hydrogen-atom abstraction leads to the radical intermediate, which can undergo SET with a hydroperoxyl radical to afforded an iminium

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• transition mostly concerned polarized molecules with both groups on its structure. Intermolecular charge transfer transition is observed for example with charge transfer complex formed by interaction an acceptor and a donor. The interaction between the two compounds induced a complex with a smaller energy

Complexation of molecular clips containing fragments of diphenylglycoluril and benzocrown ethers with paraquat and its derivatives

• Leonid S. Kikot',
• Catherine Yu. Kulygina,
• Alexander Yu. Lyapunov,
• Svetlana V. Shishkina,
• Roman I. Zubatyuk,
• Tatiana Yu. Bogaschenko and
• Tatiana I. Kirichenko

Beilstein J. Org. Chem. 2017, 13, 2056–2067, doi:10.3762/bjoc.13.203

• charge-transfer complex formed by the π-donor aromatic fragments of clips 1–5 and the π-acceptor dipyridinium fragment of paraquat derivatives 7–10 located in the pseudo cavity of the clip [20]. The intensity of this band increases with the raise of the molar ratio of paraquat:clip. The observed spectral

Mechanochemical borylation of aryldiazonium salts; merging light and ball milling

• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1463–1469, doi:10.3762/bjoc.13.144

• –solvent charge-transfer complex formation. Keywords: aryldiazonium salts; borylation; eosin Y; mechanochemistry; photocatalysis; Introduction The use of mechanical force to process materials or to induce chemical transformations is perhaps as old as the history of mankind itself [1]. Similarly, from

N-Propargylamines: versatile building blocks in the construction of thiazole cores

• S. Arshadi,
• E. Vessally,
• L. Edjlali,
• R. Hosseinzadeh-Khanmiri and
• E. Ghorbani-Kalhor

Beilstein J. Org. Chem. 2017, 13, 625–638, doi:10.3762/bjoc.13.61

• mixture of 4H-1,3-thiazines 56 and 4,5-dihydrothiazoles 57. The mechanistic course of this reaction sequence is shown in Scheme 17 and involves the initial formation of the charge-transfer complex A between the iodonium ion and the triple bond. The 5-exo-dig cyclization of this intermediate gives rise to

• 4,5-dihydrothiazoles and the competing 6-endo-dig ring-closing process affords 4H-1,3-thiazines after conversion of the charge-transfer complex into the ring-opened iodovinyl B or bridged iodirenium C ions; (2) bromine-mediated cyclizations of both electron-poor and electron-rich N-propargylthioureas

Synthesis of bi- and bis-1,2,3-triazoles by copper-catalyzed Huisgen cycloaddition: A family of valuable products by click chemistry

• Zhan-Jiang Zheng,
• Ding Wang,
• Zheng Xu and
• Li-Wen Xu

Beilstein J. Org. Chem. 2015, 11, 2557–2576, doi:10.3762/bjoc.11.276

• from binaphthol [27] (Scheme 10). Notably, this type of compound showed high selectivity over the recognition of I−, possibly due to the formation of a charge-transfer complex between the I− and the electron-deficient triazole ring. Bistriazoles formed through spacers Bistriazole synthesis with

Urethane tetrathiafulvalene derivatives: synthesis, self-assembly and electrochemical properties

• Xiang Sun,
• Guoqiao Lai,
• Zhifang Li,
• Yuwen Ma,
• Xiao Yuan,
• Yongjia Shen and
• Chengyun Wang

Beilstein J. Org. Chem. 2015, 11, 2343–2349, doi:10.3762/bjoc.11.255

• explore the formation of the charge-transfer complex. For the mixture of T1 and TCNQ, five oxidation potentials at = −0.956 V (I), = −0.368 V (II), = +0.221 V (III), = +0.527 V (IV), and = +0.852 V (V) (vs saturated calomel electrode, SCE) were clearly discernible (Figure 7). The first three

Supramolecular chemistry: from aromatic foldamers to solution-phase supramolecular organic frameworks

• Zhan-Ting Li

Beilstein J. Org. Chem. 2015, 11, 2057–2071, doi:10.3762/bjoc.11.222

• of the TTF unit. Catenanes 6a and 6b are blue as a result of the charge-transfer complex between the TTF and bipyridinium units, whereas catenane 6c is orange, which is attributed to the charge-transfer complex between the dioxybenzene and bipyridinium units. Impressively, the three catenanes could

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• toward the synthesis of compounds with TTF donor units and subsequent investigation of their properties. Since the first discovery of the semiconducting properties of TTF and its cation radical [23], and the metallic behaviour of the TTF-TCNQ charge transfer complex [24], great attention was focused on

Synthesis of racemic and chiral BEDT-TTF derivatives possessing hydroxy groups and their achiral and chiral charge transfer complexes

• Sara J. Krivickas,
• Chiho Hashimoto,
• Junya Yoshida,
• Akira Ueda,
• Kazuyuki Takahashi,
• John D. Wallis and
• Hatsumi Mori

Beilstein J. Org. Chem. 2015, 11, 1561–1569, doi:10.3762/bjoc.11.172

• structures, and electrical resistivities of the achiral charge transfer complex θ21-[(S,S)-2]3[(R,R)-2]3(ClO4)2 and the chiral complex α’-[(R,R)-2]2ClO4(H2O), in comparison with those of α’-[(S,S)-2]2ClO4. The effects of introducing hydrogen bonds between hydroxymethyl groups of donors and ClO4− anions in

Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

• Awatef Ayadi,
• Aziz El Alamy,
• Olivier Alévêque,
• Magali Allain,
• Nabil Zouari,
• Mohammed Bouachrine and
• Abdelkrim El-Ghayoury

Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149

• derivatives [1] has been initiated by the high electrical conductivity discovered in a chloride salt of TTF [2] and metallic behavior in the charge-transfer complex with 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) [3]. These systems have played a major role for the preparation of molecular materials designed

Single-molecule conductance of a chemically modified, π-extended tetrathiafulvalene and its charge-transfer complex with F₄TCNQ

• Raúl García,
• M. Ángeles Herranz,
• Edmund Leary,
• M. Teresa González,
• Gabino Rubio Bollinger,
• Marius Bürkle,
• Linda A. Zotti,
• Yoshihiro Asai,
• Fabian Pauly,
• Juan Carlos Cuevas,
• Nicolás Agraït and
• Nazario Martín

Beilstein J. Org. Chem. 2015, 11, 1068–1078, doi:10.3762/bjoc.11.120

• -molecule electrical transport properties of a molecular wire containing a π-extended tetrathiafulvalene (exTTF) group and its charge-transfer complex with F4TCNQ. We form single-molecule junctions using the in situ break junction technique using a homebuilt scanning tunneling microscope with a range of

• carried out on the charge-transfer complex. Due to the fact we expected this species to have a higher conductance than the neutral molecule, we believe this supports the idea that the conductance of the neutral molecule is very low, below our measurement sensitivity. This idea is further supported by

• theoretical calculations. To the best of our knowledge, these are the first reported single-molecule conductance measurements on a molecular charge-transfer species. Keywords: break junction measurements; charge-transfer complex; DFT-based transport; molecular electronics; tetrathiafulvalene; Introduction

Trifluoromethyl-substituted tetrathiafulvalenes

• Olivier Jeannin,
• Frédéric Barrière and
• Marc Fourmigué

Beilstein J. Org. Chem. 2015, 11, 647–658, doi:10.3762/bjoc.11.73

• potentials, these donor molecules with CF3 EWG can be involved in charge transfer complexes or cation radical salts, as reported here for the CF3-subsituted EDT-TTF donor molecule. A neutral charge transfer complex with TCNQ, (EDT-TTF-CF3)2(TCNQ) was isolated and characterized through alternated stacks of

• trifluoromethyl derivative 1c, we were also able to isolate a charge transfer complex with TCNQ and a cation radical salt with FeCl4−. The structures of both compounds will be described, and the geometrical evolutions of the TTF core upon oxidation analyzed by comparison with the structure of neutral 1c. Results

• positional disorder of the fluorine atoms, at variance with the other structures described above. Furthermore, the two ester groups are not coplanar, one of them lies flat with the TTF core while the other one is almost perpendicular. Charge-transfer complex and radical cation salt The relatively low

Bis(vinylenedithio)tetrathiafulvalene analogues of BEDT-TTF

• Erdal Ertas,
• İlknur Demirtas and
• Turan Ozturk

Beilstein J. Org. Chem. 2015, 11, 403–415, doi:10.3762/bjoc.11.46

• , then rt., overnight. Reagents and conditions (i) P4S10, toluene, reflux, dark, 3 h; (ii) P4S10, toluene, reflux, 3 h; (iii) LR, toluene, reflux, overnight. Reagents and conditions (i) Hg(OAc)2–AcOH, CHCl3, 3 h, rt; (ii) (EtO)3P, 110 °C, N2, 2 h. Charge transfer complex of 5,5',6,6'-tetraphenyl-2,2'-bi

An integrated photocatalytic/enzymatic system for the reduction of CO₂ to methanol in bioglycerol–water

• Michele Aresta,
• Angela Dibenedetto,
• Tomasz Baran,
• Antonella Angelini,
• Przemysław Łabuz and
• Wojciech Macyk

Beilstein J. Org. Chem. 2014, 10, 2556–2565, doi:10.3762/bjoc.10.267

• rutin (rutin@TiO2) shows an electron injection into the conduction band of TiO2 as the result of a direct molecule-to-band charge transfer (MBCT) within the surface-formed, colored, charge-transfer complex of titanium(IV) [21]. TiO2 with an adsorbed chromium(III) anionic complex [CrF5(H2O)]2– acts as a

Proton transfers in the Strecker reaction revealed by DFT calculations

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 1765–1774, doi:10.3762/bjoc.10.184

• complex 1. The reaction begins with the addition of NH3 to the carbonyl carbon of acetaldehyde to form a Mulliken charge-transfer complex 2. This complex was firstly proposed here. In 2, the C–O bond is elongated to1.345 Å, which has an alkoxide character and the complex is not stable in the gas phase