95843-98-4Relevant academic research and scientific papers
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.
Access to and Reactivity of Fe0, Fe?I, FeI, and FeII PCcarbeneP Pincer Complexes
Kr?mer, Tobias,Leforestier, Baptiste,Manzano, Richard A.,Sung, Simon,Tinnermann, Hendrik,Wang, Qingyang,Young, Rowan D.
, p. 18168 - 18177 (2021)
Despite their promising metal–ligand cooperative reactivity, PCcarbeneP pincer ligands are rarely reported for first-row transition-metal centres. Using a dehydration methodology, we report access to an Fe0 PCcarbeneP pincer complex (1) that proceeds via an isolated α-hydroxylalkyl hydrido complex (3). Reversible carbonyl migration to the carbene position in 1 is found to allow coordination chemistry and E?H bond addition (E=H, B, Cl) across the iron–carbene linkage, representing a unique mechanism for metal–ligand cooperativity. The PCcarbeneP pincer ligand is also found to stabilize formal FeII, FeI, and Fe?I oxidation states, as demonstrated with synthesis and characterization of the complexes [11-X][BArF20] (X=Br, I), 12, and K[13]. Compound K[13] is found to be highly reactive, and abstracts hydrogen from a range of aliphatic C?H sources. Computational analysis by DFT suggests that the formal FeI and Fe?I complexes contain significant carbene radical character. The ability of the PCcarbeneP ligand scaffold to partake in metal–ligand cooperativity and to support a range of iron oxidation states renders it as potentially useful in many catalytic applications.
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.
Synthesis and characterization of rare-earth metallate amido complexes bearing the 2-amidate-functionalized indolyl ligand and their application in the hydroboration of esters with pinacolborane
Bao, Qin,Gao, Jianjian,Hong, Dongjing,Mu, Xiaolong,Song, Lulu,Wang, Shaowu,Wei, Yun,Zhou, Shuangliu,Zhu, Xiancui
, p. 2953 - 2961 (2022/02/21)
The reactions of 2-amidate-functionalized indolyl proligand 2-(2,6-iPr2C6H3NHCO)C8H5NH (H2L) with [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 were studied leading to the synthesis and characterization of a series of novel discrete trinuclear rare-earth metallate amido complexes containing the anion [{η1:(μ2-η1:η1):η1-LREN(SiMe3)2}3(μ3-Cl)]? and cation Li+(THF)4 (RE = Y(1a), Nd (1b), Sm (1c), Gd (1d), Dy (1e), Er (1f), and Yb (1g)) in good yields by silylamine elimination. All of the complexes were characterized by spectroscopic methods, elemental analyses and single-crystal X-ray diffraction, and complexes 1a and 1c were additionally characterized by NMR spectroscopy. As proof of principle of their activity, these complexes were used as precatalysts for the hydroboration of esters using HBpin as the hydride source displaying high activity under neat and room temperature conditions. As a result, the ligand, ionic and multinuclear cooperative effects on catalytic activity were observed.
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
Boric acid as a precatalyst for BH3-catalyzed hydroboration
Fontaine, Frédéric-Georges,Légaré Lavergne, Julien,To, Hoang-Minh
, p. 31941 - 31949 (2021/12/01)
We report that boric acid, BO3H3, is a good precatalyst for the BH3-catalyzed hydroboration of esters using pinacolborane as a borylation agent. Using microwave irradiation as an energy source, we demonstrated that a dozen esters were converted into the c
Readily available lithium compounds as catalysts for the hydroboration of carbodiimides and esters
Bisai, Milan Kumar,Das, Tamal,Gour, Kritika,Sen, Sakya S.,Vanka, Kumar
supporting information, (2021/06/26)
Selective and efficient hydroboration of esters and carbodiimides to alcohols and amines by two well-defined and readily accessible lithium complexes, 2,6-di-tert-butyl phenolate lithium (1a) and 1,1’-dilithioferrocene (1b) are described. A range of aliphatic, aromatic, and cyclic esters with various functional groups were selectively converted into the corresponding boronate esters. Similarly, the single hydroboration of carbodiimides with aliphatic and aromatic substituents on the nitrogen atoms was studied. A possible mechanistic pathway of the hydroboration of carbodiimides with HBpin has been proposed using NMR studies and DFT calculations. These reactions are convenient alternatives to stoichiometric hydride reduction or hydrogenation. The employing of lithium complexes is also significant, because of the need to find cheap and green alternatives to noble metal complexes.
Progressing the Frustrated Lewis Pair Abilities of N-Heterocyclic Carbene/GaR3Combinations for Catalytic Hydroboration of Aldehydes and Ketones
Bole, Leonie J.,Uzelac, Marina,Hernán-Gómez, Alberto,Kennedy, Alan R.,O'Hara, Charles T.,Hevia, Eva
supporting information, p. 13784 - 13796 (2021/07/26)
Exploiting the steric incompatibility of the tris(alkyl)gallium GaR3 (R = CH2SiMe3) and the bulky N-heterocyclic carbene (NHC) 1,3-bis(tert-butyl)imidazol-2-ylidene (ItBu), here we report the B-H bond activation of pinacolborane (HBPin), which has led to
Synthesis and Structure of a Dimeric Yttrium Complex [LSi(BH3)(C5Me4)Y(CH2SiMe3)2]2(L = PhC(N tBu)2) and Its Catalytic Application for Hydroboration of Ketones and Aldehydes
Cui, Chunming,Lou, Ke,Yi, Jianjun,Zu, Fenghua
, p. 4092 - 4097 (2021/12/17)
Treatment of cyclopentadienyl-amidinate silylene LSi(C5HMe4) (L = PhC(NtBu)2, 1) with BH3·THF yielded the silylene-borane-functionalized tetramethylcyclopentadiene LSi(BH3)-(C5HMe4) (2), which reacted with Y(CH2SiMe3)3(THF)2 to give the dimeric yittrium complex [LSi(BH3)-(C5Me4)Y(CH2SiMe3)2]2 (3). X-ray structural analysis disclosed that the dimeric structure was formed through the BH3 bridging to the yttrium atom. Complex 3 enabled catalytic hydroboration of ketones and aldehydes with excellent efficiency and chemoselectivity.
