23229-37-0Relevant articles and documents
π-Face Promoted Catalysis in Water: From Electron-deficient Molecular Cages to Single Aromatic Slides
Luo, Na,Ao, Yu-Fei,Wang, De-Xian,Wang, Qi-Qiang
, p. 3599 - 3603 (2021)
Exploiting noncovalent π-interactions particularly emerging anion-π interactions to drive efficient catalysis is fascinating. Even with exciting progresses, can anion-π activation operate in water remains elusive. Here we report the design, synthesis and catalytic studies of a class of water-soluble electron-deficient molecular cages and relevant aromatic slide compounds. The prism-like cages contain three divided, long, cationic aromatic walls which constitute three highly electron-deficient V-shape cavities. They were efficiently synthesized in two steps from a parent triformyl cage in gram-scale. Crystal structure showed the π-walls bind to the counter bromide through strong anion-π interactions. Just 5 mol% of cages were effective in catalyzing decarboxylative Aldol reactions of aldehydes and malonic acid half thioesters in water but not in organic solvents, showing a pronounced hydrophobic amplification effect. Meantime, a series of single π-slides resembling the π-wall of the cage performed equally well, while those lacking an extended π-surface were ineffective, highlighting the essential role of electron-deficient π-face on promoting the conversion.
Experimental and Theoretical Study of an Intramolecular CF3-Group Shift in the Reactions of α-Bromoenones with 1,2-Diamines
Muzalevskiy, Vasily M.,Ustynyuk, Yury A.,Gloriozov, Igor P.,Chertkov, Vyacheslav A.,Rulev, Alexander Yu.,Kondrashov, Evgeniy V.,Ushakov, Igor A.,Romanov, Alexey R.,Nenajdenko, Valentine G.
, p. 16982 - 16989 (2015/11/16)
The reactions of trifluoromethylated 2-bromoenones and N,N′-dialkyl-1,2-diamines have been studied. Depending on the structures of the starting compounds, the formation of 2-trifluoroacetylpiperazine or 3-trifluoromethylpiperazine-2-ones was observed. The mechanism of the reaction is discussed in terms of multistep processes involving sequential substitution of bromine in the starting α-bromoenones and intramolecular cyclization of the captodative aminoenones as key intermediates to form the target heterocycles. The results of theoretical calculations are in perfect agreement with the experimental data. The unique role of the trifluoromethyl group in this reaction is demonstrated.
The unexpected role of pyridine-2-carboxylic acid in manganese based oxidation catalysis with pyridin-2-yl based ligands
Pijper, Dirk,Saisaha, Pattama,De Boer, Johannes W.,Hoen, Rob,Smit, Christian,Meetsma, Auke,Hage, Ronald,Van Summeren, Ruben P.,Alsters, Paul L.,Feringa, Ben L.,Browne, Wesley R.
, p. 10375 - 10381 (2011/01/09)
A number of manganese-based catalysts employing ligands whose structures incorporate pyridyl groups have been reported previously to achieve both high turnover numbers and selectivity in the oxidation of alkenes and alcohols, using H2O2 as terminal oxidant. Here we report our recent finding that these ligands decompose in situ to pyridine-2-carboxylic acid and its derivatives, in the presence of a manganese source, H2O 2 and a base. Importantly, the decomposition occurs prior to the onset of catalysed oxidation of organic substrates. It is found that the pyridine-2-carboxylic acid formed, together with a manganese source, provides for the observed catalytic activity. The degradation of this series of pyridyl ligands to pyridine-2-carboxylic acid under reaction conditions is demonstrated by 1H NMR spectroscopy. In all cases the activity and selectivity of the manganese/pyridyl containing ligand systems are identical to that observed with the corresponding number of equivalents of pyridine-2-carboxylic acid; except that, when pyridine-2-carboxylic acid is used directly, a lag phase is not observed and the efficiency in terms of the number of equivalents of H 2O2 required decreases from 6-8 equiv. with the pyridin-2-yl based ligands to 1-1.5 equiv. with pyridine-2-carboxylic acid.
