372-18-9Relevant articles and documents
Photoredox catalysis on unactivated substrates with strongly reducing iridium photosensitizers
Shon, Jong-Hwa,Kim, Dooyoung,Rathnayake, Manjula D.,Sittel, Steven,Weaver, Jimmie,Teets, Thomas S.
, p. 4069 - 4078 (2021/04/06)
Photoredox catalysis has emerged as a powerful strategy in synthetic organic chemistry, but substrates that are difficult to reduce either require complex reaction conditions or are not amenable at all to photoredox transformations. In this work, we show that strong bis-cyclometalated iridium photoreductants with electron-rich β-diketiminate (NacNac) ancillary ligands enable high-yielding photoredox transformations of challenging substrates with very simple reaction conditions that require only a single sacrificial reagent. Using blue or green visible-light activation we demonstrate a variety of reactions, which include hydrodehalogenation, cyclization, intramolecular radical addition, and prenylationviaradical-mediated pathways, with optimized conditions that only require the photocatalyst and a sacrificial reductant/hydrogen atom donor. Many of these reactions involve organobromide and organochloride substrates which in the past have had limited utility in photoredox catalysis. This work paves the way for the continued expansion of the substrate scope in photoredox catalysis.
Protodeboronation of (Hetero)Arylboronic Esters: Direct versus Prehydrolytic Pathways and Self-/Auto-Catalysis
Assante, Michele,Geogheghan, Katherine J.,Hayes, Hannah L. D.,Jin, Na,Leach, Andrew G.,Lloyd-Jones, Guy C.,Noonan, Gary,Tomasi, Simone,Wei, Ran
supporting information, p. 14814 - 14826 (2021/09/13)
The kinetics and mechanism of the base-catalyzed hydrolysis (ArB(OR)2→ ArB(OH)2) and protodeboronation (ArB(OR)2→ ArH) of a series of boronic esters, encompassing eight different polyols and 10 polyfluoroaryl and heteroaryl moieties, have been investigated by in situ and stopped-flow NMR spectroscopy (19F,1H, and11B), pH-rate dependence, isotope entrainment,2H KIEs, and KS-DFT computations. The study reveals the phenomenological stability of boronic esters under basic aqueous-organic conditions to be highly nuanced. In contrast to common assumption, esterification does not necessarily impart greater stability compared to the corresponding boronic acid. Moreover, hydrolysis of the ester to the boronic acid can be a dominant component of the overall protodeboronation process, augmented by self-, auto-, and oxidative (phenolic) catalysis when the pH is close to the pKaof the boronic acid/ester.
Continuous synthesis method of m-difluorobenzene based on micro-channel reactor
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Paragraph 0026-0063, (2021/04/10)
The invention discloses a continuous synthesis method of m-difluorobenzene based on a micro-reactor. The continuous synthesis method comprises the following steps: adding m-phenylenediamine and a hydrochloric acid solution into a first micro-channel reactor, and conducting reacting to obtain an m-phenylenediamine hydrochloride solution; subjecting the m-phenylenediamine hydrochloride solution to reacting with nitrogen trioxide in a second micro-channel reactor to prepare a dichlorom-phenylenediamine diazonium salt solution; subjecting the dichlorom-phenylenediamine diazonium salt to reacting with fluoboric acid in a tubular reactor, conducting quick centrifuging after the reaction is finished, washing precipitates obtained by centrifuging, and drying the precipitates to obtain m-phenylenediamine diazonium difluoroborate; and mixing the m-phenylenediamine diazonium difluoroborate with a solvent, adding the obtained mixture into a reactor, carrying out heating for decomposition, carrying out atmospheric distillation on a product in the reactor after the decomposition is finished, and collecting a fraction with a temperature of 82-84 DEG C. According to the invention, nitrogen trioxide is used as a diazotization agent, so the reaction is green, and no by-product is produced; and centrifugal mother liquor in the reaction process is concentrated and then recycled, so cost is saved, and reaction efficiency is high.
Novel manufacturing method of fluoro-aryl compounds and derivatives thereof
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Paragraph 0225-0228, (2020/01/25)
The invention relates to a novel method of manufacturing fluoro-aryl compounds and derivatives thereof, in particular, fluorobenzene and derivatives thereof. The production environment of the manufacturing method is environmentally friendly. The shortages of a conventional method are overcome through a simple and beneficial mode. Compared with the prior art, the provided method is more effective,more environmentally friendly, and more energy saving. The method is used to produce core fluorinated aromatic compounds, preferably, core fluorinated fluorobenzene. On one aspect, the invention provides a method, which is advantages in industry and uses HF and a halogenated benzene precursor to prepare fluorobenzene and hydrogen halide. Moreover, the invention provides chlorobenzene as the primary raw material to prepare fluorobenzene, which is an important material in industry, and a beneficial, unexpected and simple application of chlorobenzene. In the prior art, the provided application ofchlorobenzene is unknown.
Efficient synthesis method of meta-fluoranisole (by machine translation)
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, (2020/06/05)
The method is characterized by comprising the following steps: taking m-chloronitrobenzene as a raw material, carrying out high-temperature chlorination reaction, nitration reaction and fluorination reaction to obtain 2,4 - 2,4 -difluorobenzene and carrying out a methoxylation reaction with m-difluorobenzene as a raw material and carrying out methoxylation reaction to obtain m-fluorobenzyl ether; and the hydrogenation catalyst is a porous alumina loaded NiO-Co222O3-MoOO3 composite catalyst. The method disclosed by the invention is simple in process and high in product yield. (by machine translation)
Gold Catalyzed Decarboxylative Cross-Coupling of Iodoarenes
Daley, Ryan A.,Morrenzin, Aaron S.,Neufeldt, Sharon R.,Topczewski, Joseph J.
supporting information, p. 13210 - 13218 (2020/09/01)
This report details a decarboxylative cross-coupling of (hetero)aryl carboxylates with iodoarenes in the presence of a gold catalyst (>25 examples, up to 96% yield). This reaction is site specific, which overcomes prior limitations associated with gold catalyzed oxidative coupling reactions. The reactivity of the (hetero)aryl carboxylate correlates qualitatively to the field effect parameter (Fortho). Reactions with isolated gold complexes and DFT calculations support a mechanism proceeding through oxidative addition at a gold(I) cation with decarboxylation being viable at either a gold(I) or a silver(I) species.
Aryl dechlorination and defluorination with an organic super-photoreductant
Glaser, Felix,Kerzig, Christoph,Larsen, Christopher B.,Wenger, Oliver S.
, p. 1035 - 1041 (2020/08/28)
Direct excitation of the commercially available super-electron donor tetrakis(dimethylamino)ethylene (TDAE) with light-emitting diodes at 440 or 390 nm provides a stoichiometric reductant that is able to reduce aryl chlorides and fluorides. The method is very simple and requires only TDAE, substrate, and solvent at room temperature. The photoactive excited state of TDAE has a lifetime of 17.3 ns in cyclohexane at room temperature and an oxidation potential of ca. -3.4 V vs. SCE. This makes TDAE one of the strongest photoreductants able to operate on the basis of single excitation with visible photons. Direct substrate activation occurs in benzene, but acetone is reduced by photoexcited TDAE and substrate reduction takes place by a previously unexplored solvent radical anion mechanism. Our work shows that solvent can have a leveling effect on the photochemically available redox power, reminiscent of the pH-leveling effect that solvent has in acid-base chemistry.
Ni: Vs. Pd in Suzuki-Miyaura sp2-sp2 cross-coupling: A head-to-head study in a comparable precatalyst/ligand system
West, Matthew J.,Watson, Allan J. B.
supporting information, p. 5055 - 5059 (2019/06/03)
The Suzuki-Miyaura reaction is a cornerstone method for sp2-sp2 cross-coupling in industry. There has been a concerted effort to enable the use of Ni catalysis as an alternative to Pd in order to mitigate cost and improve sustainability. Despite significant advances, ligand development for Ni-catalyzed Suzuki-Miyaura cross-coupling remains underdeveloped when compared to Pd and, as a consequence, ligands for Ni-catalyzed processes are typically taken from the Pd arena. In this study we evaluate the effect of using a similar Ni and Pd precatalyst based on a common bidentate ligand (dppf) in a head-to-head format for the most common type of biaryl couplings, establishing the practical implications of direct replacement of Pd with Ni, and identifying the potential origins of these observations in a mechanistic context.
Synthesis and Characterization of Strong Cyclometalated Iridium Photoreductants for Application in Photocatalytic Aryl Bromide Hydrodebromination
Shon, Jong-Hwa,Sittel, Steven,Teets, Thomas S.
, p. 8646 - 8658 (2019/09/12)
A series of potent bis-cyclometalated iridium photoreductants with electron-rich β-diketiminate (NacNac) ancillary ligands is described. Structure-property analysis reveals that substituent modification of the NacNac ligands has a large effect on the ground-state IrIV/IrIII potential, which shifts cathodically as the NacNac is made more electron-rich. In addition, the excited-state IrIV/?IrIII potentials are ca. 300-500 mV more negative than that of fac-Ir(ppy)3 (ppy = 2-phenylpyridine), indicating that these compounds have much more reducing excited states. Rate constants for excited-state electron transfer between these photosensitizers and benzophenone are -2-3 times faster than fac-Ir(ppy)3, demonstrating that these complexes are both kinetically and thermodynamically more potent for excited-state electron transfer. We use these photosensitizers to optimize a simple reaction procedure for photocatalytic debromination of aryl bromide substrates, which requires only the photosensitizer, blue light, and an amine base, without silanes or other additives that are used in previously reported methods.
A Predictive Model for the Decarboxylation of Silver Benzoate Complexes Relevant to Decarboxylative Coupling Reactions
Crovak, Robert A.,Hoover, Jessica M.
, p. 2434 - 2437 (2018/02/28)
Decarboxylative coupling reactions offer an attractive route to generate functionalized arenes from simple and readily available carboxylic acid coupling partners, yet they are underutilized due to limitations in the scope of carboxylic acid coupling partner. Here we report that the field effect parameter (F) has a substantial influence on the rate of decarboxylation of well-defined silver benzoate complexes. This finding provides the opportunity to surpass current substrate limitations associated with decarboxylation and to enable widespread utilization of decarboxylative coupling reactions.
