6380-03-6Relevant articles and documents
Lewis Acid Regulated Divergent Catalytic Reaction between Quinone Imine Ketals (QIKs) and 1,3-Dicarbonyl Compounds: Switchable Access to Multiple Products Including 2-Aryl-1,3-Dicarbonyl Compounds, Indoles, and Benzofurans
Chen, Xingyu,Lu, Sixian,Deng, Ping,Chang, Xiaoqiang,Zhao, Yifan,Ma, Yue,Zhang, Dong,Xia, Fei,Yang, Lan,Wang, Jigang,Sun, Peng
supporting information, p. 94 - 102 (2021/10/05)
A catalytic Lewis acid regulated reaction between quinone imine ketals (QIKs) and 1,3-dicarbonyl compounds provides a divergent and tunable approach to a variety of skeletons, including a series of 2-aryl-1,3-dicarbonyl compounds, indoles, and benzofurans. The use of lithium chloride and ferrous bromide gives C3- or C2-alkylation products of the QIKs. The combination of ferrous bromide and trifluoromethanesulfonic acid delivers indole derivatives. Sequential hydrolysis and C3-alkylation occur in the presence of ytterbium (III) trifluoromethanesulfonate and stoichiometric amounts of water. When the reaction is performed with trifluoromethanesulfonic acid and stoichiometric amounts of water, benzofuran is obtained. This protocol utilizes mild conditions, exhibits regio- and chemoselectivity, and has broad functional group tolerance. (Figure presented.).
Selective C(sp2)-H Amination Catalyzed by High-Valent Cobalt(III)/(IV)-bpy Complex Immobilized on Silica Nanoparticles
Budnikova, Yulia,Bochkova, Olga,Khrizanforov, Mikhail,Nizameev, Irek,Kholin, Kirill,Gryaznova, Tatyana,Laskin, Artem,Dudkina, Yulia,Strekalova, Sofia,Fedorenko, Svetlana,Kononov, Aleksandr,Mustafina, Asia
, p. 5615 - 5624 (2019/11/11)
High-valent cobaltIV-bpy complex stabilized in silica matrix was detected as catalytically active form and intermediate in cobalt-mediated oxidative C?H/NH cross-coupling reaction. These CoIV species prepared by electrooxidation of CoIII(bpy)3-doped silica nanoparticles (SNs) at relatively low anodic potentials have demonstrated high catalytic activity. Both size and architecture of the SNs are highlighted as the factors beyond the complex structure affecting its oxidation potential and catalytic efficiency. The factors have been optimized for the catalyst with high efficiency, easy separation and reusability for 7 times at least. The optimal nanocatalyst (1 mol%) provides 100 % conversion of reactants in a single step of ligand-directed coupling of H2NTs with arenes under electrochemical regeneration conditions. The results emphasize both synthetic route for efficient embedding of CoIII(bpy)3 into silica support and the electrochemical generation of CoIV complexes as a facile route for developing the efficient nanocatalyst of oxidative functionalization. The observed reactivity has the potential in development of Co-catalyzed coupling reactions.
Characteristic Hydrogen Bonding Observed in the Crystals of Aromatic Sulfonamides: 1D Chain Assembly of Molecules and Chiral Discrimination on Crystallization
Kikkawa, Shoko,Masu, Hyuma,Katagiri, Kosuke,Okayasu, Misaki,Yamaguchi, Kentaro,Danjo, Hiroshi,Kawahata, Masatoshi,Tominaga, Masahide,Sei, Yoshihisa,Hikawa, Hidemasa,Azumaya, Isao
, p. 2936 - 2946 (2019/05/10)
N-Phenylbenzenesulfonamides exist preferentially in (+)- or (-)-synclinal conformations, which place the aromatic rings at both ends in the same direction with a twist. We have systematically analyzed the crystal structure of secondary aromatic sulfonamides bearing methyl, ethyl, and/or methoxy groups on the benzene rings. Intermolecular hydrogen bonding between the sulfonamide protons and sulfonyl oxygens was observed in 81 out of 85 crystals. The intermolecular hydrogen-bonding patterns could be classified into four types, i.e. Dimeric, Zigzag, Helical, and Straight patterns, with retention of the synclinal conformation of the sulfonamide moiety. We investigated the relationship between the hydrogen-bonding pattern and the proportion of the compounds that show chiral crystallization. On the basis of our classification of the intermolecular hydrogen bonds of aromatic sulfonamides, the crystals with Dimeric and Zigzag patterns, which both have enantiomeric synclinal conformers, intrinsically become achiral, except for kryptoracemates. In contrast, a high proportion of compounds with Helical or Straight patterns in the crystals showed chiral crystallization. Our classification is useful for discussion regarding the chirality of molecular assemblies, on the basis of the conformational chirality of the molecules in the crystal.
