114446-55-8Relevant academic research and scientific papers
A commentary on the self assembly and properties of a chiral titanium alkoxide cyclic trimer
Hegarty, Philip,Lau, Raymond,Motherwell, William B.
, p. 1851 - 1853 (2003)
Preselection of 3,4-di-O-benzyl-D-manitol 1 as a ligand for the exchange reaction with titanium tetraisopropoxide immediately precludes monomer formation. Thereafter, the chemistry of self-assembly dictates the formation of the cyclic trimer 2.
Continuous Flow Asymmetric Transfer Hydrogenation with Long Catalyst Lifetime and Low Metal Leaching
Kawakami, Yuji,Borissova, Antonia,Chapman, Michael R.,Goltz, Gert,Koltsova, Eleonora,Mitrichev, Ivan,Blacker, A. John
, p. 7499 - 7505 (2019)
Homogenous iridium complexes with asymmetric ligands and different tether lengths have been solid-supported and prepared in multi-gram quantities. Packed in a fixed-bed, they have been used in continuous flow for up to 120 hours in the asymmetric transfer hydrogenation of APs in 2-propanol to make 1-phenethyl alcohols in > 95 % conversion and ee. The CsDPEN ligand and C5 tether showed higher performance than TsDPEN and the C14 tether, whilst the ketone feed concentration and reaction temperature were optimized to enable the catalyst to be used at 5 mol-% loading with a residence time of 39 minutes. The total amount iridium leaching of from the support during sustained operation was 58–147 ppm. The flow system gives higher catalyst turnover numbers than the related batch reactions, but the nature and concentration of the base were found to influence strongly the catalyst's performance, with the finding that triethylamine maintains high enantioselectivity but slowly deactivates the catalyst, whilst potassium tert-butoxide does the opposite. The utility of the system is shown in the high ee's and good conversions achieved for a range of aryl alcohols.
Highly efficient and recyclable heterogeneous asymmetric transfer hydrogenation of ketones in water
Liu, Pei Nian,Deng, Jin Gen,Tu, Yong Qiang,Wang, Shao Hua
, p. 2070 - 2071 (2004)
A highly efficient heterogeneous asymmetric transfer hydrogenation of ketones in water was developed for the first time, which exhibited excellent enantioselectivities, distinct acceleration effect and remarkably high recyclabilities.
Manganese-Catalyzed Enantioselective Hydrogenation of Simple Ketones Using an Imidazole-Based Chiral PNN Tridentate Ligand
Chen, Jiachen,Hou, Huacui,Ling, Fei,Nian, Sanfei,Wu, Feifei,Xu, Min,Yi, Xiao,Zhong, Weihui
, p. 285 - 289 (2020)
A series of Mn(I) catalysts containing imidazole-based chiral PNN tridentate ligands with controllable 'side arm' groups have been established, enabling the inexpensive base-promoted asymmetric hydrogenation of simple ketones with outstanding activities (up to 8200 TON) and good enantioselectivities (up to 88.5percent ee). This protocol features wide substrate scope and functional group tolerance, thereby providing easy access to a key intermediate of crizotinib.
Efficient Heterogeneous Asymmetric Transfer Hydrogenation of Ketones Using Highly Recyclable and Accessible Silica-Immobilized Ru-TsDPEN Catalysts
Liu, Pei Nian,Gu, Pei Ming,Wang, Fei,Tu, Yong Qiang
, p. 169 - 172 (2004)
(Matrix presented) Chiral Ru-TsDPEN [N-(p-toluenesulfonyl)-1,2- diphenylethylenediamine]-derived catalysts were first successfully immobilized onto amorphous silica gel and mesoporous silicas of MCM-41 and SBA-15 by an easily accessible approach. The catalyst immobilized on silica gel demonstrated remarkably high catalytic activities and excellent enantioselectivities (up to >99% ee) for the heterogeneous asymmetric transfer hydrogenation of various ketones. Particularly, the catalyst could be readily recovered and reused in multiple consecutive catalytic runs (up to 10 uses) with the completely maintained enantioselectivity.
Asymmetric hydrogenation of aromatic ketones by chiral (1S,2S)-DPEN-Ru(II)Cl2(TPP)2 encapsulated in SBA-16
Liu, Jianhong,Fan, Binbin,Liang, Dong,Shi, Xiufeng,Li, Ruifeng,Chen, Hua
, p. 373 - 377 (2010)
Chiral complex (1S,2S)-DPEN-RuCl2(TPP)2 (DPEN = 1,2-diphenylethylenediamine; TPP = triphenylphosphine) was successfully encapsulated in the mesoporous cage of SBA-16 modified with phenyltrimethoxysilane. This was verified by ICP, powder XRD, N2 adsorption, FTIR, DRS and TEM analysis. The encapsulated chiral Ru complex gave high catalytic activity and excellent enantioselectivity like its homogeneous counterpart in asymmetric hydrogenation of various aromatic ketones. The encapsulated complex also showed high stability and could be recycled without significant loss of activity and enantioselectivity.
Fine-tuning of the substrate binding mode to enhance the catalytic efficiency of an: Ortho -haloacetophenone-specific carbonyl reductase
Li, Aipeng,Li, Xue,Pang, Wei,Tian, Qing,Wang, Ting,Zhang, Lianbing
, p. 2462 - 2472 (2020)
Carbonyl reductase BaSDR1 has been identified as a potential ortho-haloacetophenone-specific biocatalyst for the synthesis of chiral 1-(2-halophenyl)ethanols due to its excellent stereoselectivity. However, the catalytic efficiency of BaSDR1 is far below the required level for practical applications. Thus, fine-tuning of the substrate binding mode, which aimed at maximum preservation of the positive factors for substrate specificity and stereoselectivity, was proposed as a tentative strategy for enhancing its catalytic efficiency. The designed mutants Q139S, D253Y and Q139S/D253Y showed significantly enhanced catalytic efficiency. Remarkably, the variants Q139S and Q139S/D253Y exhibited a more than 9-fold improvement in catalytic efficiency (kcat/Km) toward substrates 6a and 11a, respectively. More importantly, none of the variants caused activity-stereoselectivity trade-off and all variants exhibited excellent stereoselectivity (99% ee). Analysis of variant-substrate complexes showed that the mutations indeed enable the fine-tuning of the substrate binding mode. New strengthening factors for consolidating the productive conformation were introduced while the original positive factors were preserved. Furthermore, at a substrate concentration of 100 mM, recombinant E. coli whole cells expressing the BaSDR1 mutants were successfully applied to the synthesis of several key intermediates of chiral pharmaceuticals, including (S)-1-(2-chlorophenyl)ethanol, (S)-1-(2,4-difluorophenyl)ethanol and (S)-1-(2,6-difluorophenyl)ethanol, with 99% enantiomeric excess, and the conversion reached over 95% in a certain period of time. These results demonstrated the effectiveness of the strategy involving the fine-tuning of the substrate binding mode and the applicability of the designed mutants in efficient reduction of ortho-haloacetophenones.
Asymmetric reduction of acetophenone analogues by Alternaria alternata using ram horn peptone
Kurbanoglu, Esabi B.,Zilbeyaz, Kani,Kurbanoglu, Namudar I.,Kilic, Hamdullah
, p. 2332 - 2335 (2007)
Alternaria alternata EBK-4 fungus isolated from a plant sample was evaluated for the asymmetric reduction of acetophenone analogues. In a previous study, this isolate was used for the reduction of acetophenone to 1-phenylethanol in excellent enantiomeric excess. The substituted acetophenones were converted to the corresponding optically active alcohol by A. alternata EBK-4 under optimized conditions in up to >99% enantiomeric excess (ee). This is the first report on the enantiomeric reduction of acetophenone analogues by A. alternata using ram horn peptone from waste material.
Novel (R)-(+)-limonene-derived ligands: Synthesis and application in asymmetric transfer hydrogenations
Roszkowski, Piotr,Maurin, Jan K.,Czarnocki, Zbigniew
, p. 1106 - 1110 (2012)
(R)-(+)-Limonene was transformed into mono-N-tosylated-1,2-diamine derivatives using an N-tosylaziridination procedure followed by sodium azide treatment and reduction on Pd/C. The ligands obtained proved effective in the asymmetric transfer hydrogenation protocol on aromatic ketones.
Facile synthesis of hybrid core-shell nanospheres for the asymmetric transfer hydrogenation of aromatic ketones
Wei, Juan,Zhang, Xiaomin,Zhang, Xiaoming,Zhao, Yaopeng,Li, Ruixiang,Yang, Qihua
, p. 1368 - 1374 (2014)
The polymer-inorganic hybrid core-shell nanospheres with N-(para-toluenesulfonyl)-1,2-diphenylethylenediamine in the core and the poly(methyl acrylate) (PMA) polymer in the shell were prepared by using a sol-gel process. The surface properties of solid catalysts were modified by controlling PMA and the cetyltrimethylammonium bromide surfactant in the shell. The water contact angle results suggest that the presence of PMA and cetyltrimethylammonium bromide in the shell increases the surface hydrophobicity. In the Rh-catalyzed transfer hydrogenation of aromatic ketones in aqueous HCOONa, the solid catalyst with higher surface hydrophobicity demonstrates higher activity, which suggests that suitable surface properties increase the reaction rate by increasing the diffusion rates of hydrophobic substrates. Furthermore, this heterogeneous catalyst can be reused conveniently without loss of ee values. Clever condensation: A sol-gel process is used for the synthesis of polymer-inorganic hybrid core-shell composites with a mixture of poly(methyl acrylate)-organosilane (PMA SiO2) and tetraethoxysilane as a co-condensed silane source and the polystyrene-supported N-(para-toluenesulfonyl)-1,2-diphenylethylenediamine-type ligand as a polymer core. These core-shell materials demonstrate high reactivity and excellent ee values for the asymmetric transfer hydrogenation of aromatic ketones in aqueous HCOONa.
