7401-84-5Relevant academic research and scientific papers
Metal-Free Transfer Hydroiodination of C-C Multiple Bonds
Chen, Weiqiang,Walker, Johannes C. L.,Oestreich, Martin
supporting information, p. 1135 - 1140 (2019/01/11)
The design and a gram-scale synthesis of a bench-stable cyclohexa-1,4-diene-based surrogate of gaseous hydrogen iodide are described. By initiation with a moderately strong Br?nsted acid, hydrogen iodide is transferred from the surrogate onto C-C multiple bonds such as alkynes and allenes without the involvement of free hydrogen iodide. The surrogate fragments into toluene and ethylene, easy-to-remove volatile waste. This hydroiodination reaction avoids precarious handling of hydrogen iodide or hydroiodic acid. By this, a broad range of previously unknown or difficult-to-prepare vinyl iodides can be accessed in stereocontrolled fashion.
Iron-catalysed enantioselective Suzuki-Miyaura coupling of racemic alkyl bromides
Iwamoto, Takahiro,Okuzono, Chiemi,Adak, Laksmikanta,Jin, Masayoshi,Nakamura, Masaharu
supporting information, p. 1128 - 1131 (2019/01/28)
The first iron-catalysed enantioselective Suzuki-Miyaura coupling reaction has been developed. In the presence of catalytic amounts of FeCl2 and (R,R)-QuinoxP?, lithium arylborates are cross-coupled with tert-butyl α-bromopropionate in an enantioconvergent manner, enabling facile access to various optically active α-arylpropionic acids including several nonsteroidal anti-inflammatory drugs (NSAIDs) of commercial importance. (R,R)-QuinoxP? is specifically able to induce chirality when compared to analogous P-chiral ligands that give racemic products, highlighting the critical importance of transmetalation in the present asymmetric cross-coupling system.
Cobalt-bisoxazoline-catalyzed asymmetric kumada cross-coupling of racemic α-bromo esters with aryl grignard reagents
Mao, Jianyou,Liu, Feipeng,Wang, Min,Wu, Lin,Zheng, Bing,Liu, Shangzhong,Zhong, Jiangchun,Bian, Qinghua,Walsh, Patrick J.
supporting information, p. 17662 - 17668 (2015/02/02)
The first cobalt-catalyzed asymmetric Kumada cross-coupling with high enantioselectivity has been developed. The reaction affords a unique strategy for the enantioselective arylation of α-bromo esters catalyzed by a cobalt-bisoxazoline complex. A variety of chiral α-arylalkanoic esters were prepared in excellent enantioselectivity and yield (up to 97% ee and 96% yield). The arylated products were transformed into α-arylcarboxylic acids and primary alcohols without erosion of ee. The new enantioenriched α-arylpropionic esters synthesized herein are potentially useful in the development of nonsteroidal anti-inflammatory drugs. This method was conducted on gram-scale and applied to the synthesis of highly enantioenriched (S)-fenoprofen and (S)-ar-turmerone.
Highly selective synthesis of α-bromoesters using molecular bromine catalyzed by phosphorus
Sun, Zhaoyun,Peng, Xinhua,Dong, Xiongzi,Shi, Wenwen
scheme or table, p. 929 - 930 (2012/07/30)
A series of α-bromoesters have been synthesized by applying Hell-Volhard-Zelinsky reaction catalyzed by phosphorus instead of usual phosphorus tribromide. An excellent regioselectivity to good yields are achieved at comparatively mild reaction conditions of an operational simplicity.
Inclusion complexes of EMPO derivatives with 2,6-di-O-methyl-β- cyclodextrin: Synthesis, NMR and EPR investigations for enhanced superoxide detection
Bardelang, David,Rockenbauer, Antal,Karoui, Hakim,Finet, Jean-Pierre,Biskupska, Inga,Banaszak, Karol,Tordo, Paul
, p. 2874 - 2882 (2008/02/08)
The free radical trapping properties of eight 5-alkoxycarbonyl-5-methyl-1- pyrroline N-oxide (EMPO) type nitrones and those of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) were evaluated for trapping of superoxide anion radicals in the presence of 2,6-di-O-methyl-β-cyclodextrin (DM-β-CD). 1H-NMR titrations were performed to determine both stoichiometries and binding constants for the diamagnetic nitrone-DM-β-CD equilibria. EPR titrations were then performed and analyzed using a two-dimensional EPR simulation program affording 1: 1 and 1: 2 stoichiometries for the nitroxide spin adducts with DM-β-CD and the associated binding constants after spin trapping. The nitroxide spin adducts associate more strongly with DM-β-CD than the nitrones. The ability of the nitrones to trap superoxide, the enhancement of the EPR signal intensity and the supramolecular protection by DM-β-CD against sodium l-ascorbate reduction were evaluated. The Royal Society of Chemistry 2006.
Very stable superoxide radical adducts of 5-ethoxycarbonyl-3,5-dimethyl- pyrroline N-oxide (3,5-EDPO) and its derivatives
Stolze, Klaus,Rohr-Udilova, Natascha,Rosenau, Thomas,Stadtmueller, Roswitha,Nohl, Hans
, p. 1351 - 1361 (2007/10/03)
Oxygen radicals are involved in the onset of many diseases. Adequate spin traps are required for identification and localisation of free radical formation in biological systems. Superoxide spin adducts with half-lives up to 20 min at physiological pH have recently been reported to be formed from derivatives of the spin trap 5-ethoxycarbonyl-5-methyl-1-pyrroline N-oxide (EMPO). This is a major improvement over DMPO (t1/2 ca. 45 s), and even DEPMPO (t 1/2 ca. 14 min). In this study, an additional methyl group was introduced into position 3 or 4 of the pyrroline ring which greatly increases the stability of the respective superoxide spin adducts. In addition, the ethoxy group of EMPO was exchanged by either a propoxy- or an iso-propoxy group in order to test the influence of increasing lipophilic properties of the investigated spin traps. The structure of all compounds was confirmed by 1H and 13C-NMR with full signal assignment. In comparison with EMPO (t1/2 ca. 8 min) or DEPMPO (t1/2 ca. 14 min), the superoxide adducts of all novel spin traps were considerably higher (t 1/2 ca. 12-55 min). In addition, various other spin adducts obtained from oxygen-centered as well as carbon-centered radicals (e.g. derived from methanol or linoleic acid hydroperoxide) were also detected.
Solvent dependent photochemical reactions of 3-(2-alkylphenyl)-2,2- dimethyl-3-oxopropanoates and their related compounds
Saito, Masaichi,Kamei, Yumiko,Kuribara, Kanae,Yoshioka, Michikazu,Hasegawa, Tadashi
, p. 9013 - 9018 (2007/10/03)
Photochemical reactions of methyl 3-(o-alkylphenyl)-2,2-dimethyl-3- oxopropanoates in hexane gave only the corresponding benzocyclobutenols. However, when irradiation was carried out in methanol, 3-oxonaphthalenones were produced together with the benzocyclobutenols. The ratio of benzocyclobutenol to naphthalenone depends on the bulkiness of the alkyl group in the ortho position. Intermediary 1,4-diradicals or dienols were efficiently trapped by oxygen to afford the corresponding peroxides and/or oxygenated compounds derived from the peroxides.
