5460-32-2Relevant academic research and scientific papers
Electrochemical Generation of Hypervalent Bromine(III) Compounds
Francke, Robert,Mohebbati, Nayereh,Sokolovs, Igors,Suna, Edgars
supporting information, p. 15832 - 15837 (2021/06/14)
In sharp contrast to hypervalent iodine(III) compounds, the isoelectronic bromine(III) counterparts have been little studied to date. This knowledge gap is mainly attributed to the difficult-to-control reactivity of λ3-bromanes as well as to their challenging preparation from the highly toxic and corrosive BrF3 precursor. In this context, we present a straightforward and scalable approach to chelation-stabilized λ3-bromanes by anodic oxidation of parent aryl bromides possessing two coordinating hexafluoro-2-hydroxypropanyl substituents. A series of para-substituted λ3-bromanes with remarkably high redox potentials spanning a range from 1.86 V to 2.60 V vs. Ag/AgNO3 was synthesized by the electrochemical method. We demonstrate that the intrinsic reactivity of the bench-stable bromine(III) species can be unlocked by addition of a Lewis or a Br?nsted acid. The synthetic utility of the λ3-bromane activation is exemplified by oxidative C?C, C?N, and C?O bond forming reactions.
Photocatalytic Oxidative Iodination of Electron-Rich Arenes
Narobe, Rok,Düsel, Simon J. S.,Iskra, Jernej,K?nig, Burkhard
supporting information, p. 3998 - 4004 (2019/07/17)
A visible-light-mediated oxidative iodination of electron-rich arenes has been developed. 2.5 mol% of unsubstituted anthraquinone as photocatalyst were used in combination with elementary iodine, trifluoroacetic acid and oxygen as the terminal oxidant. The iodination proceeds upon irradiation in non- or weakly-electron donating solvents (DCM, DCE and benzene) wherein a spectral window in strongly coloured iodine solutions can be observed at around 400 nm. The method provides good to excellent yields (up to 98%) and shows excellent regioselectivity and good functional group tolerance (triple bonds, ketone, ester, amide). Moreover, the photo-iodination was also upscaled to a 5 mmol scale (1.1 g). Mechanistic investigations by intermediate trapping and competition experiments indicate a photocatalytic arene oxidation and the subsequent reaction with iodine as a likely mechanistic pathway. (Figure presented.).
One-pot synthesis of unsymmetrical 1,3-butadiyne derivatives and their application in the synthesis of unsymmetrical 2,5-diarylthiophenes
Andrade, Camila B.,Carvalho, Diego B.,Trefzger, Ozildéia S.,Kassab, Najla M.,Guerrero, Palimécio G.,Barbosa, Sandro L.,Shiguemoto, Cristiane Y. K.,Baroni, Adriano C. M.
supporting information, p. 696 - 704 (2019/01/04)
A one-pot protocol was developed for the synthesis of unsymmetrical 1,3-butadiynes. The procedure is based on two sequential reactions: deprotection of R–C≡C–C≡C– C(Me)2OH derivatives in a retro-Favorskii reaction to furnish a terminal 1,3-butadiyne compound, which reacted with aryl iod-ides in a Sonogashira-type cross-coupling reaction catalyzed by Pd(PPh3)4 and CuI, using TBAOH as activator and toluene as solvent under reflux for 10 min. We also studied in situ thiocycli-zation of 1,3-butadiynes, leading to unsymmetrical 2,5-diaryl-thiophenes. The principal features of this method are operational simplicity, good substrate scope, very fast reaction, and high yields.
Iodine(III)-Mediated, Controlled Di- or Monoiodination of Phenols
Satkar, Yuvraj,Yera-Ledesma, Luisa F.,Mali, Narendra,Patil, Dipak,Segura-Quezada, Luis A.,Ramírez-Morales, Perla I.,Solorio-Alvarado, César R.,Navarro-Santos, Pedro
, p. 4149 - 4164 (2019/04/30)
An oxidative procedure for the electrophilic iodination of phenols was developed by using iodosylbenzene as a nontoxic iodine(III)-based oxidant and ammonium iodide as a cheap iodine atom source. A totally controlled monoiodination was achieved by buffering the reaction medium with K3PO4. This protocol proceeds with short reaction times, at mild temperatures, in an open flask, and generally with high yields. Gram-scale reactions, as well as the scope of this protocol, were explored with electron-rich and electron-poor phenols as well as heterocycles. Quantum chemistry calculations revealed PhII(OH)·NH3 to be the most plausible iodinating active species as a reactive "I+" synthon. In light of the relevance of the iodoarene moiety, we present herein a practical, efficient, and simple procedure with a broad functional group scope that allows access to the iodoarene core unit.
Rapid Iododeboronation with and without Gold Catalysis: Application to Radiolabelling of Arenes
Webster, Stacey,O'Rourke, Kerry M.,Fletcher, Conor,Pimlott, Sally L.,Sutherland, Andrew,Lee, Ai-Lan
supporting information, p. 937 - 943 (2017/12/26)
Radiopharmaceuticals that incorporate radioactive iodine in combination with single-photon emission computed tomography imaging play a key role in nuclear medicine, with applications in drug development and disease diagnosis. Despite this importance, there are relatively few general methods for the incorporation of radioiodine into small molecules. This work reports a rapid air- and moisture-stable ipso-iododeboronation procedure that uses NIS in the non-toxic, green solvent dimethyl carbonate. The fast reaction and mild conditions of the gold-catalysed method led to the development of a highly efficient process for the radiolabelling of arenes, which constitutes the first example of an application of homogenous gold catalysis to selective radiosynthesis. This was exemplified by the efficient synthesis of radiolabelled meta-[125I]iodobenzylguanidine, a radiopharmaceutical that is used for the imaging and therapy of human norepinephrine transporter-expressing tumours.
N-Iodosuccinimide (NIS) in Direct Aromatic Iodination
Bergstr?m, Maria,Suresh, Ganji,Naidu, Veluru Ramesh,Unelius, C. Rikard
, p. 3234 - 3239 (2017/06/21)
N-Iodosuccinimide (NIS) in pure trifluoroacetic acid (TFA) offers a time-efficient and general method for the iodination of a wide range of mono- and disubstituted benzenes at room temperature, as demonstrated in this paper. The starting materials were generally converted into mono-iodinated products in less than 16 hours at room temperature, without byproducts. A few deactivated substrates needed addition of sulfuric acid to increase the reaction rate. Another exception was methoxybenzenes that preferentially were iodinated by NIS in acetonitrile with only catalytic amounts of TFA.
Bottom-up synthesis of fully sp2 hybridized three-dimensional microporous graphitic frameworks as metal-free catalysts
Talapaneni, Siddulu Naidu,Kim, Jaehoon,Je, Sang Hyun,Buyukcakir, Onur,Oh, Jihun,Coskun, Ali
supporting information, p. 12080 - 12085 (2017/07/10)
We report on the bottom-up synthesis of a fully sp2-hybridized nitrogenated three-dimensional microporous graphitic framework (3D-MGF) starting from a highly preorganized, saddle-shaped tetraphenylene derivative under ionothermal reaction condi
Rapid aerobic iodination of arenes mediated by hypervalent iodine in fluorinated solvents
Iskra, Jernej,Murphree, S. Shaun
supporting information, p. 645 - 648 (2017/01/28)
Arenes are rapidly converted to the corresponding iodides by aerobic oxidative iodination at room temperature by treatment with iodine and catalytic quantities of nitrous acid in a fluorinated solvent. Dichloroiodic acid is proposed as the actual iodination reagent.
One-Pot, Metal-Free Conversion of Anilines to Aryl Bromides and Iodides
Leas, Derek A.,Dong, Yuxiang,Vennerstrom, Jonathan L.,Stack, Douglas E.
supporting information, p. 2518 - 2521 (2017/05/24)
A metal-free synthesis of aryl bromides and iodides from anilines via halogen abstraction from bromotrichloromethane and diiodomethane is described. This one-pot reaction affords aryl halides from the corresponding anilines in moderate to excellent yields without isolation of diazonium salts. The transformation has short reaction times, a simple workup, and insensitivity to moisture and air and avoids excess halogenation. DFT calculations support a SRN1 mechanism. This method represents a convenient alternative to the classic Sandmeyer reaction.
Novel chromone and xanthone derivatives: Synthesis and ROS/RNS scavenging activities
Proen?a, Carina,Albuquerque, Hélio M.T.,Ribeiro, Daniela,Freitas, Marisa,Santos, Clementina M.M.,Silva, Artur M.S.,Fernandes, Eduarda
, p. 381 - 392 (2016/04/06)
Chromones and xanthones are oxygen-containing heterocyclic compounds acknowledged by their antioxidant properties. In an effort to develop novel agents with improved activity, a series of compounds belonging to these chemical classes were prepared. Their syntheses involve the condensation of appropriate 2-methyl-4H-chromen-4-ones, obtained via Baker-Venkataraman rearrangement, with (E)-3-(3,4-dimethoxyphenyl)acrylaldehyde to provide the corresponding 2-[(1E,3E)-4-(3,4-dimethoxyphenyl)buta-1,3-dien-1-yl]-4H-chromen-4-ones. Subsequent electrocyclization and oxidation of these compounds led to the synthesis of 1-aryl-9H-xanthen-9-ones. After cleavage of the protecting groups, hydroxylated chromones and xanthones were assessed as scavenging agents against both reactive oxygen species (ROS) [superoxide radical (O2?-), hydrogen peroxide (H2O2), hypochlorous acid (HOCl), singlet oxygen (1O2), and peroxyl radical (ROO?)] and reactive nitrogen species (RNS) [nitric oxide (?NO) and peroxynitrite anion (ONOO-)]. Generally, all the tested new hydroxylated chromones and xanthones exhibited scavenger effects dependent on the concentration, with IC50 values found in the micromolar range. Some of them were shown to have improved scavenging activity when compared with previously reported analogues, allowing the inference of preliminary conclusions on the structure-activity relationship.
