95843-98-4Relevant articles and documents
Selective Hydroboration of Carboxylic Acids with a Homogeneous Manganese Catalyst
Barman, Milan K.,Das, Kuhali,Maji, Biplab
, p. 1570 - 1579 (2019)
Catalytic reduction of carboxylic acid to the corresponding alcohol is a challenging task of great importance for the production of a variety of value-added chemicals. Herein, a manganese-catalyzed chemoselective hydroboration of carboxylic acids has been developed with a high turnover number (>99?000) and turnover frequency (>2000 h-1) at 25 °C. This method displayed tolerance of electronically and sterically differentiated substrates with high chemoselectivity. Importantly, aliphatic long-chain fatty acids, including biomass-derived compounds, can efficiently be reduced. Mechanistic studies revealed that the reaction occurs through the formation of active manganese-hydride species via an insertion and bond metathesis type mechanism.
Catalytic Hydroboration of Esters by Versatile Thorium and Uranium Amide Complexes
Makarov, Konstantin,Kaushansky, Alexander,Eisen, Moris S.
, p. 273 - 284 (2022/01/03)
The challenging hydroboration of esters is achieved using simple uranium and thorium amides, U[N(SiMe3)2]3 and [(Me3Si)2N]2An[κ2-(N,C)-CH2Si(CH3)2N(SiMe3)] (An = Th or U) acting as precatalysts in the reaction with pinacolborane (HBpin). All three complexes showed impressive catalytic activities, reaching excellent yields. A large scope of esters was investigated including aliphatic, aromatic, and heterocyclic esters that were transformed cleanly to the corresponding hydroborated alcohols, which readily hydrolyzed to the free alcohols. Moreover, the actinide catalysts demonstrated unexpected high functional tolerance toward nitro, halide, cyano, and heteroaromatic functional groups. The reaction exhibited excellent selectivity toward the ester when additional double and triple unsaturated C-C bonds were present. Lactones and poly caprolactone have been successfully cleaved to the monomeric units, showing a great promise toward polymer degradation and recycling. Detailed kinetic studies are provided in order to determine the rate dependence on the concentration of catalyst, HBpin, and ester. A plausible mechanism is proposed based on stoichiometric reactions, DFT calculations, thermodynamic measurements, and deuterium-labeling studies.
Hydroborative reduction of amides to amines mediated by La(CH2C6H4NMe2-: O)3
Gong, Mingliang,Guo, Chenjun,Luo, Yunjie,Xie, Hongzhen,Zhang, Fangcao
, p. 779 - 791 (2022/01/22)
The deoxygenative reduction of amides to amines is a great challenge for resonance-stabilized carboxamide moieties, although this synthetic strategy is an attractive approach to access the corresponding amines. La(CH2C6H4NMe2-o)3, a simple and easily accessible lanthanide complex, was found to be highly efficient not only for secondary and tertiary amide reduction, but also for the most challenging primary reduction with pinacolborane. This protocol exhibited good tolerance for many functional groups and heteroatoms, and could be applied to gram-scale synthesis. The active species in this catalytic cycle was likely a lanthanide hydride.
Super hydride catalyzed ester and isocyanate hydroboration
Behera, Bedabyas,Ding, Yi,Du, Zonggang,Kumar, Arun
supporting information, (2021/08/09)
Commercially available, eco-friendly lithium triethylborohydride (LiHBEt3, Super hydride) was shown to be an excellent catalyst for the solvent-free hydroboration of esters using pinacolborane at ambient reaction conditions. This was achieved w
