5338-94-3Relevant academic research and scientific papers
Rhodium-Catalyzed Regiodivergent Synthesis of Alkylboronates via Deoxygenative Hydroboration of Aryl Ketones: Mechanism and Origin of Selectivities
Zhang, Bing,Xu, Xin,Tao, Lei,Lin, Zhenyang,Zhao, Wanxiang
, p. 9495 - 9505 (2021/08/04)
Here, we report an efficient rhodium-catalyzed deoxygenative borylation of ketones to synthesize alkylboronates, in which the regioselectivity can be switched by the choice of the ligand. The linear alkylboronates were obtained exclusively in the presence of P(nBu)3, and PPh2Me favored the formation of branched alkylboronates. The protocol also allows access to 1,1,2-triboronates from the readily available ketones. Mechanistic studies suggest that this Rh-catalyzed deoxygenative borylation of ketones goes through an alkene intermediate, which undergoes regiodivergent hydroboration to afford linear and branched alkylboronates. The different steric effects of PPh2Me and P(nBu)3 were found to be responsible for product selectivity by density functional theory calculations. The alkene intermediate can alternatively undergo sequential dehydrogenative borylation and hydroboration to deliver the triboronates.
Low-valence anionic α-diimine iron complexes: Synthesis, characterization, and catalytic hydroboration studies
Bodensteiner, Michael,Coburger, Peter,Demeshko, Serhiy,Gawron, Martin,Maier, Thomas M.,Meyer, Franc,Wolf, Robert,de Bruin, Bas,van Leest, Nicolaas P.
, p. 16035 - 16052 (2020/11/20)
The synthesis of rare anionic heteroleptic and homoleptic α-diimine iron complexes is described. Heteroleptic BIAN (bis(aryl)iminoacenaphthene) complexes 1-[K([18]c-6)-(thf)0.5] and 2-[K([18]c-6)(thf)2] were synthesized by reduction of the [(BIAN)FeBr2] precursor complex using stoichiometric amounts of potassium graphite in the presence of the corresponding olefin. The electronic structure of these paramagnetic species was investigated by numerous spectroscopic analyses (NMR, EPR, 57Fe M?ssbauer, UV-vis), magnetic measurements (Evans NMR method, SQUID), and theoretical techniques (DFT, CASSCF). Whereas anion 1 is a low-spin complex, anion 2 consists of an intermediate-spin Fe(III) center. Both complexes are efficient precatalysts for the hydroboration of carbonyl compounds under mild reaction conditions. The reaction of bis(anthracene) ferrate(1-) gave the homoleptic BIAN complex 3-[K([18]c-6)(thf)], which is less catalytically active. The electronic structure was elucidated with the same techniques as described for complexes 1-[K([18]c-6)(thf)0.5] and 2-[K([18]c-6)(thf)2] and revealed an Fe(II) species in a quartet ground state.
Base-Mediated Meerwein-Ponndorf-Verley Reduction of Aromatic and Heterocyclic Ketones
Boit, Timothy B.,Mehta, Milauni M.,Garg, Neil K.
supporting information, p. 6447 - 6451 (2019/08/20)
An experimental protocol to achieve the Meerwein-Ponndorf-Verley (MPV) reduction of ketones under mildly basic conditions is reported. The transformation is tolerant of a range of ketone substrates, including O- and S-containing heterocycles, is scalable, and shows potential to be used as a platform to access enantioenriched products. These studies provide a general method for achieving the reduction of ketones under mildly basic conditions and offer an alternative protocol to more well-known Al-based MPV reduction conditions.
N, O-coordination mode rhodium complex and synthesis method and use thereof
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Paragraph 0045; 0046, (2017/08/31)
The invention belongs to the technical field of coordination chemistry, and in particular relates to an N, O-coordination mode rhodium complex and a synthesis method and use thereof. The central atom of the N, O-coordination mode rhodium complex is rhodium (Rh). The N, O-coordination mode rhodium complex is prepared by synthesis of a ligand by use of 1H-pyrrole-2-carboxylate as a starting material and further effect of the ligand and Rh (COD) 2BF4, and the N, O-coordination mode rhodium complex can be used as an acetophenone derivative reduction reaction catalyst. The N, O-coordination mode rhodium complex has the advantages of simple synthesis process, better selectivity and yield. The catalytic activity of the N, O-coordination mode rhodium complex as the catalyst is high.
A General, Practical Triethylborane-Catalyzed Reduction of Carbonyl Functions to Alcohols
Peng, Dongjie,Zhang, Mintao,Huang, Zheng
supporting information, p. 14737 - 14741 (2015/10/19)
A combination of the abundant and low-cost triethylborane and sodium alkoxide generates a highly efficient catalyst for reduction of esters, as well as ketones and aldehydes, to alcohols using an inexpensive hydrosilane under mild conditions. The catalyst system exhibits excellent chemoselectivity and a high level of functional group tolerance. Mechanistic studies revealed a resting state of sodium triethylalkoxylborate that is the product of the reaction of BEt3 with sodium alkoxide. This borate species reacts with hydrosilane to form NaBEt3H, which rapidly reduces esters.
Synthesis, characterization and application of nickel(II) complexes modified with N,N′,N″-pincer ligands
Czerny, Frank,D?hlert, Peter,Weidauer, Maik,Irran, Elisabeth,Enthaler, Stephan
supporting information, p. 118 - 123 (2015/02/02)
Different N,N″-substituted pyridine-2,6-dicarboxamides 1a-d have been synthesized and treated with nickel(II) trifluoromethanesulfonate in the presence of an excess of tetraethylammonium hydroxide to form after double-deprotonation the nickel hydroxido complexes 4a-c. These square planar complexes have been characterized by various techniques, which indicate a tridentate N,N′,N″-coordination mode of the ligands. The other coordination site on the nickel center is occupied by a hydroxido ligand. The reactivity of the complexes was studied in dehalogenation reactions and allows access to square planar nickel chlorido complexes 5a-c. Moreover, by NMR studies it was found that nickel hydroxido complexes as well as chlorido complexes can be converted with diphenylsilane or lithium borohydride to nickel hydrido complexes, which can be seen as a possible catalytic intermediate in reduction chemistry. Based on that, the potential of complexes 4 and 5 were evaluated in the hydrosilylation of ketones to produce alcohols after work-up.
Asymmetric Reduction of Electron-Rich Ketones with Tethered Ru(II)/TsDPEN Catalysts Using Formic Acid/Triethylamine or Aqueous Sodium Formate
Soni, Rina,Hall, Thomas H.,Mitchell, Benjamin P.,Owen, Matthew R.,Wills, Martin
, p. 6784 - 6793 (2015/10/06)
The asymmetric transfer hydrogenation (ATH) of ketones under aqueous conditions using tethered Ru(II)/6-arene/diamine catalysts is described, as is the ATH of electron-rich substrates containing amine and methoxy groups on the aromatic rings. Although such substrates are traditionally challenging ones for ATH, the tethered catalysts work very efficiently. In the case of amino-substituted ketones, aqueous conditions give excellent results; however, for methoxy-substituted substrates, the more established formic acid/triethylamine system gives superior results.
Commutative reduction of aromatic ketones to arylmethylenes/alcohols by hypophosphites catalyzed by Pd/C under biphasic conditions
Guyon, Carole,Baron, Marc,Lemaire, Marc,Popowycz, Florence,Métay, Estelle
, p. 2088 - 2095 (2014/03/21)
An efficient method is reported to reduce aromatic ketones selectively into arylmethylenes or alcohols with hypophosphites and Pd/C, depending on the selected conditions. This study could represent a promising alternative to the classical uses of standard hydrides or molecular hydrogen involved in reduction and deoxygenation procedures.
Ruthenium-catalyzed transfer hydrogenation of amino- and amido-substituted acetophenones
Watson, Andrew J. A.,Fairbanks, Antony J.
supporting information, p. 6784 - 6788 (2013/11/06)
The ruthenium-catalyzed transfer hydrogenation of electron-rich amino-substituted acetophenones is reported. Variation of the reductant, ligands, base, and solvent allowed reaction optimization. A key discovery was the use of 1,4-butanediol as an irreversible reducing agent, which significantly improved the conversion. A range of amino- and amido-substituted aryl ketones were explored, and they all gave the corresponding alcohols in good yield, which demonstrates the wider applicability of this process. The ruthenium-catalyzed reduction of electron-rich amino-substituted acetophenones with 1,4-butanediol as an irreversible reducing agent is reported. Optimization of the conditions and variation of the amino substituent are explored as is the use of amido- and sulfonamidoacetophenones with varying results. Copyright
Bis(imino)pyridine iron complexes for aldehyde and ketone hydrosilylation
Tondreau, Aaron M.,Lobkovsky, Emil,Chirik, Paul J.
supporting information; experimental part, p. 2789 - 2792 (2009/05/27)
(Chemical Equation Presented) Bis(imino)pyridine iron dinitrogen and dialkyl complexes are well-defined precatalysts for the chemo- and regioselective reduction of aldehydes and ketones. Efficient carbonyl hydrosilylation is observed at low (0.1-1.0 mol %) catalyst loadings and with 2 equiv of either PhSiH3 or Ph2SiH2, representing one of the most active iron-catalyzed carbonyl reductions reported to date.
