440-60-8Relevant articles and documents
Mono- and Di-Mesoionic Carbene-Boranes: Synthesis, Structures and Utility as Reducing Agents
Stein, Felix,Kirsch, Marius,Beerhues, Julia,Albold, Uta,Sarkar, Biprajit
supporting information, p. 2417 - 2424 (2021/06/17)
Mesoionic carbenes (MIC) of the 1,2,3-triazol-5-ylidene type are currently popular ligands in organometallic chemistry. Their use in main group chemistry has been rather limited. In this contribution we present mono- and di-MIC-boranes with MICs based on triazolylidenes. The synthesis involves in-situ deprotonation of the corresponding triazolium salts and their reaction with boranes to form the desired compounds. Whereas this reaction route worked well for all triazolium salts derived from the 1,4-regioisomer of the triazoles, for the methlyene-bridged bi-triazolium salt derived from a 1,5-substiuted triazole, we observed the unexpected decomposition of the bi-triazolium and the formation of a triazole-borane with a new N?B bond. All compounds were characterized via multinuclear NMR spectroscopy, mass spectrometry, and single crystal X-ray diffraction. Furthermore, the MIC-boranes were used as reducing agents for the reduction of the C=O of aldehydes to the corresponding alcohols.
Chemoselective and Site-Selective Reductions Catalyzed by a Supramolecular Host and a Pyridine-Borane Cofactor
Morimoto, Mariko,Cao, Wendy,Bergman, Robert G.,Raymond, Kenneth N.,Toste, F. Dean
supporting information, p. 2108 - 2114 (2021/02/06)
Supramolecular catalysts emulate the mechanism of enzymes to achieve large rate accelerations and precise selectivity under mild and aqueous conditions. While significant strides have been made in the supramolecular host-promoted synthesis of small molecules, applications of this reactivity to chemoselective and site-selective modification of complex biomolecules remain virtually unexplored. We report here a supramolecular system where coencapsulation of pyridine-borane with a variety of molecules including enones, ketones, aldehydes, oximes, hydrazones, and imines effects efficient reductions under basic aqueous conditions. Upon subjecting unprotected lysine to the host-mediated reductive amination conditions, we observed excellent ?-selectivity, indicating that differential guest binding within the same molecule is possible without sacrificing reactivity. Inspired by the post-translational modification of complex biomolecules by enzymatic systems, we then applied this supramolecular reaction to the site-selective labeling of a single lysine residue in an 11-amino acid peptide chain and human insulin.
Copper(II)-Catalyzed Selective Hydroboration of Ketones and Aldehydes
Zeng, Haisu,Wu, Jing,Li, Sihan,Hui, Christina,Ta, Anita,Cheng, Shu-Yuan,Zheng, Shengping,Zhang, Guoqi
, p. 401 - 406 (2019/01/23)
A novel nonanuclear copper(II) complex obtained by a facile one-pot self-assembly was found to catalyze the hydroboration of ketones and aldehydes with the absence of an activator under mild, solvent-free conditions. The catalyst is air- and moisture-stable, displaying high efficiency (1980 h-1 turnover frequency, TOF) and chemoselectivity on aldehydes over ketones and ketones over imines. This represents a rare example of divalent copper catalyst for the hydroboration of carbonyls.
Method for preparing polyfluorobenzyl alcohol
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Paragraph 0039; 0040, (2018/05/16)
The invention relates to a method for preparing polyfluorobenzyl alcohol, and belongs to the technical field of organic synthesis. The method comprises the following steps: 1. allowing polyfluorobenzoic acid and a dehydrating reagent to a reflux reaction; 2 adding sodium borohydride to a product obtained in step 1 to perform a reduction reaction to obtain the polyfluorobenzyl alcohol. Although themethod provided by the invention requires two steps, the selectivity of the two-step reaction is high, no side reaction exists, no organic three wastes exist, and the yield is also higher than that of the existing method.
Half-sandwich ruthenium(II) complexes with water-soluble Schiff base ligands: Synthesis and catalytic activity in transfer hydrogenation of carbonyl compounds
Azizi Talouki, Somayeh,Grivani, Gholamhossein,Crochet, Pascale,Cadierno, Victorio
, p. 142 - 148 (2016/12/23)
New ionic Schiff-base ligands have been synthesized by condensation of (3-formyl-4-hydroxybenzyl)triphenylphosphonium and 3-(3-formyl-4-hydroxybenzyl)-1-methyl-1H-imidazol-3-ium chloride and hexafluorophosphate salts with N,N-dimethylethylenediamine. Treatment of the dimeric derivative [{RuCl(μ-Cl)(η6-p-cymene)}2] with two equivalents of these ligands allowed the preparation of novel mononuclear water-soluble Ru(II) complexes, which proved to be catalytically active in the transfer hydrogenation of ketones and aldehydes under aqueous conditions.
Cooperative interplay between a flexible PNN-Ru(II) complex and a NaBH4 additive in the efficient catalytic hydrogenation of esters
Wang, Zheng,Chen, Xiangyang,Liu, Bo,Liu, Qing-Bin,Solan, Gregory A.,Yang, Xinzheng,Sun, Wen-Hua
, p. 1297 - 1304 (2017/05/05)
A catalyst loading of between 0.001-0.05 mol% of the PNN-bearing ruthenium(II) complex [fac-PNN]RuH(PPh3)(CO) (PNN = 8-(2-diphenylphosphinoethyl)amidotrihydroquinoline), in combination with 5 mol% NaBH4, efficiently catalyzes the hydrogenation of esters to their corresponding alcohols under mild pressures of hydrogen. Both aromatic and aliphatic esters can be converted with high values of TON or TOF achievable. Mechanistic investigations using both DFT calculations and labeling experiments highlight the cooperative role of NaBH4 in the catalysis while the catalytically active species has been established as trans-dihydride [mer-PNHN]RuH2(CO) (PNHN = 8-(2-diphenylphosphinoethyl)aminotrihydroquinoline). The stereo-structure of the PNHN-ruthenium species greatly affects the activity of the catalyst, and indeed the cis-dihydride isomer [fac-PNHN]RuH2(CO) is unable to catalyze the hydrogenation of esters until ligand reorganization occurs to give the trans isomer.
Piano-stool benzothiazol-2-ylidene Ru(II) complexes for effective transfer hydrogenation of carbonyls
Oru?, Zeynep ?pek,G?k, Lütfiye,Türkmen, Hayati,?ahin, Onur,Büyükgüng?r, Orhan,?etinkaya, Bekir
, p. 36 - 44 (2017/11/15)
Benzothiazolium bromides (NSHC.HBr) (1a-j) with a variety of alkyl chain or benzyl substituents on N atom were prepared. The synthesis of ruthenium(II) (NSHC) complexes, (2a–j) could be achieved by in situ deprotonation of benzothiazolium salts with Ag2O and [RuCl2(p-cymene)]2. They were characterized by 1H, 13C, 19F NMR, IR spectroscopy and elemental analysis. The molecular structures of 2d, 2e and 2g were ascertained by single-crystal X-ray diffraction studies. The catalytic properties of complexes, (2a–j), with electron-donating or -withdrawing groups were investigated in transfer hydrogenation (TH) of ketones, and aldehydes with good to excellent yields. The presence of the CH2(CH2)16CH3 or CH2C6F5 on the N atom of the benzothiazol-2-ylidene complexes (2g, 2j) showed the highest activity for TH reaction. The catalytic properties of the N-alkyl substituted ruthenium(II) (NSHC) complexes(2h–j) may be interpreted by micelle effects.
Aluminum Monohydride Catalyzed Selective Hydroboration of Carbonyl Compounds
Jakhar, Vineet Kumar,Barman, Milan Kr.,Nembenna, Sharanappa
, p. 4710 - 4713 (2016/09/28)
The well-defined aluminum monohydride compound [{(2,4,6-Me3-C6H2)NC(Me)}2(Me)(H)]AlH·(NMe2Et) (1) catalyzes hydroboration of a wide range of aldehydes and ketones under mild reaction conditions. Moreover, compound 1 displayed chemoselective hydroboration of aldehydes over ketones at rt.
Dinickel complexes with anthyridine-based ligands
Huang, Da-Wei,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
, p. 8265 - 8271 (2016/06/09)
Two new dinickel complexes with anthyridine-based ligands, 5-phenyl-2,8-bis(2-pyridinyl)-1,9,10-anthyridine (L2) and 5-phenyl-2,8-bis(6′-bipyridinyl)-1,9,10-anthyridine (L3), are reported. Complexation of Ni(OAc)2 with L2 and L3 in trifluoroacetic acid provided the corresponding dinickel complexes [{Ni2(L2)(H2O)6(CF3COO)2}(CF3COO)2] (2) and [Ni2(L3)(CF3COO)4(H2O)] (3), respectively. Both complexes were characterized by spectroscopic methods and further confirmed by X-ray crystallography. Structural analyses of 2 and 3 revealed the Ni?Ni distances in the complexes to be 5.4086(6) and 5.0138(7) ?, respectively. The catalytic activities of complexes 2 and 3 toward the reduction of carboxylic acids were evaluated. It appears that complex 3 shows a good catalytic activity toward the reduction of carboxylates into the corresponding alcohols by diphenylsilane.
Method for preparing alcohol through catalytic hydrogenation reduction of carboxylate
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Paragraph 0023; 0025; 0040, (2016/12/07)
The invention discloses a method for preparing alcohol through catalytic hydrogenation reduction of a carboxylate compound with 2-(diphenylphosphinoethyl)-(5,6,7,8-tetrahydroquinolyl)amine as a ruthenium complex catalyst of ligand. The catalyst has high-efficiency catalysis activity on alkyl benzoate, aromatic esters and fatty esters. The preparation method is simple and has good stability, the catalysis activity of the catalyst is high, and the dosage of the catalyst is 0.025-0.005% of the mole of a substrate. The method can be used for producing alcohols, and has the advantages of simplicity, small pollution to environment, high yield and low cost. Most of carboxylate can be hydrogenated and reduced to form alcohols by using a complex represented by formula (1) with sodium borohydride as an additive, and the conversion number TOC can reach 50000; and a cocaalyst sodium borohydride is used to substitute most of alcoholic alkalis used as a catalyst in especially used in aromatic esters with electron-withdrawing substituent, so the cost is reduced, operation is simple, and industrial production is easy.
