93-54-9Relevant articles and documents
A new heterometallic coordination polymer: Synthesis, structure, and catalytic property
Liu, Qi-Feng,Liu, Wei,Cao, Yi-Po,Dong, Yan-Li,Liu, Hui-Min
, p. 153 - 157 (2017)
A new heterometallic-organic framework, namely [CuCa(tdc)2(DMF)]n(1 H2tdc = 2,5-thiophenedicarboxylic acid, DMF = N,N’-dimethylformamide), has been successfully obtained through the solvothermal reactions of CuCl2, Ca(NO3)2, and H2tdc. Single-crystal structural analysis reveals that compound 1 features a 3D framework with the irl topology. Compound 1 has potential unsaturated metal sites after the removal of the coordinated DMF molecules, so it exhibits excellent catalytic activity for the diethylzinc addition to benzaldehyde.
Kinetic investigations of product inhibition in the amino alcohol-catalyzed asymmetric alkylation of benzaldehyde with diethylzinc
Rosner, Thorsten,Sears, Patrick J.,Nugent, William A.,Blackmond, Donna G.
, p. 2511 - 2513 (2000)
(equation presented) In situ reaction rate measurements help to define the role of product inhibition in the asymmetric alkylation of benzaldehyde with diethylzinc using (-)-MIB as a chiral reagent. Reaction calorimetry and kinetic modeling demonstrated that the rate behavior over consecutive reactions may only be rationalized when reversible binding of the product alkoxide is taken into consideration. These results may have implications for the conversion dependence of product enantioselctivity in reactions using enantioimpure catalysts.
RZnI vs. R2Zn in Pd(0)-catalyzed cross-coupling reactions with thioimidates
Roberts, William P.,Ghosh, Indranath,Jacobi, Peter A.
, p. 279 - 284 (2004)
Thioimidates 1-Z undergo facile cross-coupling with Pd(0)-RZnI but are inert to Pd(0)-R2Zn. This difference is due to the lower Lewis acidity of R2Zn, as opposed to lower nucleophilicity. Various sources of RZnI (R = Me, Et) and Pd(0) were evaluated for their convenience and reactivity.
A novel approach to conformationally strained 2,2′-bipyridine thiacrown ethers and their chiral sulfoxides by sequential homo-coupling/DA-rDA reaction of 5,5′-bi-1,2,4-triazine-containing thiamacrocycles
?awecka, Justyna,Karczmarzyk, Zbigniew,Wolińska, Ewa,Olender, Ewa,Branowska, Danuta,Rykowski, Andrzej
, p. 3098 - 3104 (2011)
The synthesis of conformationally strained 2,2′-bipyridine thiamacrocycles 5, 6, 9, 10 and their chiral sulfoxides 11-14 is elaborated using, (1) homo-coupling of 1,2,4-triazine sulfide 3 with potassium cyanide and (2) Diels-Alder/retro Diels-Alder (DA-rDA) with 2,5-norbornadiene or 1-pyrrolidino-1-cyclopentene as the key steps. The crystal structure determinations of 4-6 and the theoretical calculations at DFT/B3LYP/6-311 G level were conducted thus establishing conformational preferences of the target thiamacrocycles
Hydrolysis of Phosphonothioates with a Binaphthyl Group: P-Stereogenic O-Binaphthyl Phosphonothioic Acids and Their Use as Optically Active Ligands and Chiral Discriminating Agents
Kuwabara, Kazuma,Maekawa, Yuuki,Minoura, Mao,Murai, Toshiaki
, p. 1375 - 1379 (2018)
The hydrolysis of phosphonothioates with a binaphthyl group afforded the first example of O-(2′-hydroxy)binaphthyl phosphonothioic acids in good to high yields and >95:5 diastereoselectivity. The reaction proceeds via an axis-to-center chirality-transfer reaction. The ability of these acids to act as chiral molecular auxiliaries was demonstrated by using them as optically active ligands for the asymmetric ethylation of benzaldehyde and as a chiral discriminating agent for chiral aliphatic amines.
Catalytic enantioselective addition of diethylzinc to 1,3-dithian-2-yl substituted aliphatic aldehydes: A new approach to optically active 2-(hydroxyalkyl)-1,3-dithianes
Wilken, Joerg,Winter, Martin,Stahl, Ingfried,Martens, Juergen
, p. 1067 - 1071 (2000)
Asymmetric synthesis of 2-(hydroxyalkyl)-1,3-dithianes was achieved in good yields of up to 81% by using various 1,3-dithian-2-yl-substituted aliphatic aldehydes as substrates in the catalytic enantioselective addition of diethylzinc. With fair enantiomeric ratios of up to 85:15 in the enantiocontrolled ethylation step this synthetic approach provides an entry towards potential chiral building blocks. Copyright (C) 2000 Elsevier Science Ltd.
Best design of heterogenized β-aminoalcohols for improvement of enantioselective addition of diethylzinc to benzaldehyde
Abramson,Lasperas,Galarneau,Desplantier-Giscard,Brunel
, p. 1773 - 1774 (2000)
Covalent immobilization of (1R,2S)-(-)-ephedrine, used as a model molecule of β-aminoalcohols, on the surface of MCM-41-type mesoporous aluminosilicates, performed by a new sol-gel method, leads to chiral auxiliaries which show greatly enhanced rates and ee's compared to those reported up to now in the enantioselective addition of diethylzinc to benzaldehyde.
Aromatic C?H Hydroxylation Reactions with Hydrogen Peroxide Catalyzed by Bulky Manganese Complexes
Masferrer-Rius, Eduard,Borrell, Margarida,Lutz, Martin,Costas, Miquel,Klein Gebbink, Robertus J. M.
, p. 3783 - 3795 (2021/03/09)
The oxidation of aromatic substrates to phenols with H2O2 as a benign oxidant remains an ongoing challenge in synthetic chemistry. Herein, we successfully achieved to catalyze aromatic C?H bond oxidations using a series of biologically inspired manganese catalysts in fluorinated alcohol solvents. While introduction of bulky substituents into the ligand structure of the catalyst favors aromatic C?H oxidations in alkylbenzenes, oxidation occurs at the benzylic position with ligands bearing electron-rich substituents. Therefore, the nature of the ligand is key in controlling the chemoselectivity of these Mn-catalyzed C?H oxidations. We show that introduction of bulky groups into the ligand prevents catalyst inhibition through phenolate-binding, consequently providing higher catalytic turnover numbers for phenol formation. Furthermore, employing halogenated carboxylic acids in the presence of bulky catalysts provides enhanced catalytic activities, which can be attributed to their low pKa values that reduces catalyst inhibition by phenolate protonation as well as to their electron-withdrawing character that makes the manganese oxo species a more electrophilic oxidant. Moreover, to the best of our knowledge, the new system can accomplish the oxidation of alkylbenzenes with the highest yields so far reported for homogeneous arene hydroxylation catalysts. Overall our data provide a proof-of-concept of how Mn(II)/H2O2/RCO2H oxidation systems are easily tunable by means of the solvent, carboxylic acid additive, and steric demand of the ligand. The chemo- and site-selectivity patterns of the current system, a negligible KIE, the observation of an NIH-shift, and the effectiveness of using tBuOOH as oxidant overall suggest that hydroxylation of aromatic C?H bonds proceeds through a metal-based mechanism, with no significant involvement of hydroxyl radicals, and via an arene oxide intermediate. (Figure presented.).
Reduction of carbonyl compounds via hydrosilylation catalyzed by well-defined PNP-Mn(I) hydride complexes
Weber, Stefan,Iebed, Dina,Glatz, Mathias,Kirchner, Karl
, p. 635 - 639 (2021/06/17)
Reduction reactions of unsaturated compounds are fundamental transformations in synthetic chemistry. In this context, the reduction of polarized double bonds such as carbonyl or C=C motifs can be achieved by hydrogenation reactions. We describe here a highly chemoselective Mn(I)-based PNP pincer catalyst for the hydrosilylation of aldehydes and ketones employing polymethylhydrosiloxane (PMHS) as inexpensive hydrogen donor. Graphic abstract: [Figure not available: see fulltext.]
