935-67-1Relevant articles and documents
Decarboxylative cross-nucleophile coupling via ligand-to-metal charge transfer photoexcitation of Cu(ii) carboxylates
Li, Qi Yukki,Gockel, Samuel N.,Lutovsky, Grace A.,DeGlopper, Kimberly S.,Baldwin, Neil J.,Bundesmann, Mark W.,Tucker, Joseph W.,Bagley, Scott W.,Yoon, Tehshik P.
, p. 94 - 99 (2022/01/11)
Reactions that enable carbon–nitrogen, carbon–oxygen and carbon–carbon bond formation lie at the heart of synthetic chemistry. However, substrate prefunctionalization is often needed to effect such transformations without forcing reaction conditions. The development of direct coupling methods for abundant feedstock chemicals is therefore highly desirable for the rapid construction of complex molecular scaffolds. Here we report a copper-mediated, net-oxidative decarboxylative coupling of carboxylic acids with diverse nucleophiles under visible-light irradiation. Preliminary mechanistic studies suggest that the relevant chromophore in this reaction is a Cu(ii) carboxylate species assembled in situ. We propose that visible-light excitation to a ligand-to-metal charge transfer (LMCT) state results in a radical decarboxylation process that initiates the oxidative cross-coupling. The reaction is applicable to a wide variety of coupling partners, including complex drug molecules, suggesting that this strategy for cross-nucleophile coupling would facilitate rapid compound library synthesis for the discovery of new pharmaceutical agents. [Figure not available: see fulltext.].
N -Arylbenzo[ b ]phenothiazines as Reducing Photoredox Catalysts for Nucleophilic Additions of Alcohols to Styrenes: Shift towards Visible Light
Seyfert, Fabienne,Wagenknecht, Hans-Achim
supporting information, p. 582 - 586 (2021/01/25)
N -Phenylphenothiazines are an important class of photoredox catalysts because they are synthetically well accessible, they allow the tuning of the optoelectronic properties by different substituents, and they have strong reduction properties for activation of alkenes. One of the major disadvantages of N -phenylphenothiazines, however, is the excitation at 365 nm in the UV-A light range. We synthesized three differently dialkylamino-substituted N -phenylbenzo[ b ]phenothiazines as alternative photoredox catalysts and applied them for the nucleo philic addition of alkohols to α-methyl styrene. The additional benzene ring shift the absorbance bathochromically and allows performing the photocatalyses by excitation at 385 nm and 405 nm. This type of photoredox catalysis tolerates other functional groups, as representatively shown for alcohols as substrates with C-C and C-N triple bonds.
Visible Light Promoted, Catalyst-Free Radical Carbohydroxylation and Carboetherification under Mild Biomimetic Conditions
Altmann, Lisa-Marie,Zantop, Viviane,Wenisch, Pia,Diesendorf, Nina,Heinrich, Markus R.
, p. 2452 - 2462 (2020/12/30)
Metal and catalyst-free carbohydroxylations and carboetherifications at room temperature have been achieved by a combination of beneficial factors including high aryl diazonium concentration and visible light irradiation. The acceleration of the reaction by visible light irradiation is particularly remarkable against the background that neither the aryldiazonium salt nor the alkene show absorptions in the respective range of wavelength. These observations point to weak charge transfer interactions between diazonium salt and alkene, which are nevertheless able to considerably influence the reaction course. As highly promising perspective, many more aryldiazonium-based radical arylations might benefit from simple light irradiation without requiring a photocatalyst or particular additive.
Reactivity and Product Analysis of a Pair of Cumyloxyl and tert-Butoxyl Radicals Generated in Photolysis of tert-Butyl Cumyl Peroxide
Oyama, Ryoko,Abe, Manabu
, p. 8627 - 8638 (2020/07/21)
Alkoxyl radicals play important roles in various fields of chemistry. Understanding their reactivity is essential to applying their chemistry for industrial and biological purposes. Hydrogen-atom transfer and C-C β-scission reactions have been reported from alkoxyl radicals. The ratios of these two processes were investigated using cumyloxyl (CumO?) and tert-butoxyl radicals (t-BuO?), respectively. However, the products generated from the pair of radicals have not been investigated in detail. In this study, CumO? and t-BuO? were simultaneously generated from the photolysis of tert-butyl cumyl peroxide to understand the chemical behavior of the pair of radicals by analyzing the products and their distribution. Electron paramagnetic resonance and/or transient absorption spectroscopy analyses of radicals, including CumO? and t-BuO?, provide more information about the radicals generated during the photolysis of tert-butyl cumyl peroxide. Furthermore, the photoproducts of (3-(tert-butylperoxy)pentane-3-yl)benzene demonstrated that the ether products were formed in in-cage reactions. The triplet-sensitized reaction induced by acetophenone, which is produced from CumO?, clarified that the spin state did not affect the product distribution.
N-Arylphenothiazines as strong donors for photoredox catalysis – pushing the frontiers of nucleophilic addition of alcohols to alkenes
Speck, Fabienne,Rombach, David,Wagenknecht, Hans-Achim
, p. 52 - 59 (2019/01/28)
A new range of N-phenylphenothiazine derivatives was synthesized as potential photoredox catalysts to broaden the substrate scope for the nucleophilic addition of methanol to styrenes through photoredox catalysis. These N-phenylphenothiazines differ by their electron-donating and electron-withdrawing substituents at the phenyl group, covering both, σ and π-type groups, in order to modulate their absorbance and electrochemical characteristics. Among the synthesized compounds, alkylaminylated N-phenylpheno-thiazines were identified to be highly suitable for photoredox catalysis. The dialkylamino substituents of these N-phenylpheno-thiazines shift the estimated excited state reduction potential up to ?3.0 V (vs SCE). These highly reducing properties allow the addition of methanol to α-methylstyrene as less-activated substrate for this type of reaction. Without the help of an additive, the reaction conditions were optimized to achieve a quantitative yield for the Markovnivkov-type addition product after 20 h of irradiation.
Selective reaction of benzyl alcohols with HI gas: Iodination, reduction, and indane ring formations
Matsumoto, Shoji,Naito, Masafumi,Oseki, Takehisa,Akazome, Motohiro,Otani, Yasuhiko
, p. 7254 - 7259 (2017/11/24)
Reactions of benzyl alcohols with HI in solvent-free conditions were examined. Three types of reactions (iodination, reduction, and ring formation) occurred depending on the degree of crowding around the benzyl position and the benzylic stabilization of substrates. Results also showed that the ring formation to give indanes proceeded efficiently when HI was used, and that compounds with electron-rich aromatic rings gave indane derivatives in good yields.
Carbocationic polymerization of isoprene using cumyl initiators: Progress in understanding side reactions
Ouardad, Samira,Wirotius, Anne-Laure,Kostjuk, Sergei,Ganachaud, Fran?ois,Peruch, Frédéric
, p. 59218 - 59225 (2016/01/09)
The cationic polymerization of isoprene using cumyl chloride/B(C6F5)3 and cumyl ether/TiCl4 systems was investigated in dichloromethane or in dichloromethane/methylcyclohexane mixtures varying the polymerization conditions. Polymerizations were performed in all cases in the presence of a large excess of a proton trap (2,6-di-tert-butyl pyridine, dtBP) compared to initiator in order to suppress any protic side reactions. As a consequence, no polymerization went to completion. Independently of the reaction conditions, trans-1,4-oligomers were exclusively obtained with mainly an olefinic terminal group. It was highlighted that an important loss of double bonds yielding saturated parts was observed, even in the absence of protons, assuming that a great amount of double bond loss generally observed in isoprene cationic polymerization could be due to intramolecular cyclization reactions. Nevertheless, under particular conditions (low temperature and/or low polarity medium), branching and cross-linking reactions were also found responsible for double bond loss.
Hydrochloric acid as an efficient catalyst for intermolecular condensation of alcohols. A simple and highly efficient synthesis of unsymmetrical ethers from benzylic alcohols and alkanols
Mochalov,Fedotov,Trofimova,Zefirov
, p. 1217 - 1231 (2015/11/09)
Benzylic alcohols and diarylmethanols with electron-donating substituents in the aromatic ring reacted with aliphatic alcohols in the presence of a catalytic amount of HCl to give the corresponding alkyl arylmethyl ethers. The reactivity of diarylmethanols in the intermolecular dehydration depended on the nature of substituents in the aromatic rings and structure of aliphatic alcohol.
Indium(i)-catalyzed alkyl-allyl coupling between ethers and an allylborane
Dao, Hai Thanh,Schneider, Uwe,Kobayashi, Shu
supporting information; experimental part, p. 692 - 694 (2011/03/22)
An efficient method for alkyl-allyl cross-coupling between ethers and a 9-BBN-derived allylborane catalyzed by indium(i) triflate has been developed. The allylborane proved to be essential to obtain the desired products in high yields. The reaction displayed good substrate scope including high functional group tolerance. The Royal Society of Chemistry 2011.
Metal-free activation of dioxygen by graphene/g-C3N4 nanocomposites: Functional dyads for selective oxidation of saturated hydrocarbons
Li, Xin-Hao,Chen, Jie-Sheng,Wang, Xinchen,Sun, Jianhua,Antonietti, Markus
supporting information; scheme or table, p. 8074 - 8077 (2011/07/08)
Graphene sheet/polymeric carbon nitride nanocomposite (GSCN) functions as a metal-free catalyst to activate O2 for the selective oxidation of secondary C-H bonds of cyclohexane. By fine-tuning the weight ratio of graphene and carbon nitride components, GSCN offers good conversion and high selectivity to corresponding ketones. Besides its high stability, this catalyst also exhibits high chemoselectivity for secondary C-H bonds of various saturated alkanes and, therefore, should be useful in overcoming challenges confronted by metal-mediated catalysis.
