1195-66-0Relevant articles and documents
Implications of CO2 Activation by Frustrated Lewis Pairs in the Catalytic Hydroboration of CO2: A View Using N/Si+ Frustrated Lewis Pairs
Von Wolff,Lefèvre,Berthet,Thuéry,Cantat
, p. 4526 - 4535 (2016)
A series of base-stabilized silylium species were synthesized and their reactivity toward CO2 explored, yielding the characterization of a novel N/Si+ FLP-CO2 adduct. These silicon species are active catalysts in the hydroboration of CO2 to the methoxide level with 9-BBN, catecholborane (catBH), and pinacolborane (pinBH). Both experiments and DFT calculations highlight the role of the FLP-CO2 adduct in the catalysis. Depending on the nature of the hydroborane reductant, two distinct mechanisms have been unveiled. While 9-BBN and catBH are able to reduce an intermediate FLP-CO2 adduct, the hydroboration of CO2 with pinBH follows a different and novel path where the B-H bond is activated by the silicon-based Lewis acid catalyst. In these mechanisms, the formation of a highly stabilized FLP-CO2 adduct is found detrimental to the kinetics of the reaction.
Reductive depolymerization of polyesters and polycarbonates with hydroboranes by using a lanthanum(iii) tris(amide) catalyst
Berthet, Jean-Claude,Cantat, Thibault,Kobylarski, Marie
supporting information, p. 2830 - 2833 (2022/03/09)
The homogeneous reductive depolymerization of polyesters and polycarbonates with hydroboranes is achieved with the use of an f-metal complex catalyst. These polymeric materials are transformed into their value-added alcohol equivalents. Catalysis proceeds readily, under mild conditions, with La[N(SiMe3)2]3 (1 mol%) and pinacolborane (HBpin) and shows high selectivity towards alcohols and diols, after hydrolysis.
Hydroboration of nitriles, esters, and amides catalyzed by simple neosilyllithium
Bandyopadhyay, Ayan,Bhattacharjee, Jayeeta,Kumar Singh, Saurabh,Kumari, Kusum,Moorthy, Shruti,Panda, Tarun K.,Sai Kumar, Gobbilla
supporting information, (2022/03/31)
We present here an efficient method for the hydroboration of organic nitriles, carboxylic esters, and carboxamides with pinacolborane (HBpin) using an alkali metal catalyst, neosilyllithium (LiCH2SiMe3), in neat reaction conditions. The reactions were accomplished with efficient catalytic reactivity and demonstrated by neosilyllithium at room temperature, in solvent-free condition, to afford a high yield of the corresponding N-boryl amines, boryl ethers, and amine hydrochlorides. The protocol for the catalytic reaction presented in this paper is simple and efficient, with diverse substrate scope for nitriles, carboxylic esters, and carboxamides showing excellent functional group tolerance. DLPNO-CCSD(T) calculations were also performed, showing that the hydroboration of nitriles catalyzed by neosilyllithium occurs through the pre-coordination of the nitrile at Lewis acid lithium followed by hydride migration from the B–H entity.
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.
