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.
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.
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.
