31218-75-4Relevant articles and documents
Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
supporting information, p. 9029 - 9039 (2021/06/28)
Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
Metallation reactions. Part 35: A change of the regiochemistry in the metallation of (alkylthio)arenes
Cabiddu, Maria G.,Cabiddu, Salvatore,Cadoni, Enzo,De Montis, Stefania,Fattuoni, Claudia,Melis, Stefana
, p. 3915 - 3920 (2007/10/03)
The metallation reaction of bromo(alkylthio)benzenes is described. The results show the complementarity of these reactions with the metal-hydrogen exchange reaction. In fact, monometallation of bromo(methylthio)benzenes afforded products substituted in para or meta or ortho to the thioethereal function while bimetallation led to αS,para, αS,meta and αS,ortho disubstituted products. Analogously, the monometallation of 4-bromo-(isopropylthio)benzene afforded para-monosubstituted and ortho,para-disubstituted products.
Metallation reactions. XXI. Metallation of alkyl (alkylthio) benzenes by superbases versus organolithium compounds
Cabiddu, Salvatore,Fattuoni, Claudia,Floris, Costantino,Melis, Stefana,Serci, Alessandro
, p. 6037 - 6048 (2007/10/02)
The metallation regiochemistry of alkyl(alkylthio)benzenes with butyllithium or with the superbasic mixture of butyllithium with potassium tert-butoxide is described. The reaction pattern depends on the substrate and the reagent. Butyllithium monometallates the thiomethylic carbon of methyl (methylthio) benzenes and bimetallates the thiomethylic and the annular carbon ortho to the thioethereal group. With superbases the metallation occurs at the thiomethylic and methylic carbon. Metallation with butyllithium of the higher homologs substitutes exclusively the hydrogen ortho to the thioalkylic group, while the superbases attack also the carbon atom alpha to the thioalkyl substituent.
