scholarly journals Manganese-Catalyzed Asymmetric Hydrogenation of Quinolines Enabled by a Dual “N–H Effect”

2020 ◽  
Author(s):  
Chenguang Liu ◽  
Mingyang Wang ◽  
Shihan Liu ◽  
Yujie Wang ◽  
Yong Peng ◽  
...  
Keyword(s):  
Noble Metal ◽  
Asymmetric Hydrogenation ◽  
High Reactivity ◽  
Catalyst Loading ◽  
Turnover Number ◽  
Noble Metal Catalysts ◽  
Wide Range ◽  
Metal Catalyzed ◽  
High Yields ◽  
Low Catalyst Loading

<p>The first example of non-noble metal-catalyzed asymmetric hydrogenation of aromatic <i>N</i>-heterocycles is reported. A new chiral pincer manganese catalyst showed outstanding catalytic activity in the asymmetric hydrogenation of a wide range of quinolines, affording high yields and excellent enantioselectivities (up to 97% <i>ee</i>). A turnover number of 3840 was reached at a low catalyst loading (S/C=4000), which was competitive with the activity of most effective noble metal catalysts for this reaction. The high reactivity of the manganese catalyst and a precise regulation of the enantioselectivity were ensured by a dual “N–H” effect of the ligand structure.<u></u></p>

Manganese-Catalyzed Asymmetric Hydrogenation of Quinolines Enabled by pi–pi Interaction

2020 ◽  
Author(s):  
Chenguang Liu ◽  
Mingyang Wang ◽  
Shihan Liu ◽  
Yujie Wang ◽  
Yong Peng ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Noble Metal ◽  
Asymmetric Hydrogenation ◽  
Catalyst Loading ◽  
Turnover Number ◽  
Noble Metal Catalysts ◽  
Wide Range ◽  
Metal Catalyzed ◽  
High Yields ◽  
Low Catalyst Loading

<p>The first example of non-noble metal-catalyzed asymmetric hydrogenation of aromatic <i>N</i>-heterocycles is reported. A new chiral pincer manganese catalyst showed outstanding catalytic activity in the asymmetric hydrogenation of a wide range of quinolines, affording high yields and excellent enantioselectivities (up to 97% <i>ee</i>). A turnover number of 3840 was reached at a low catalyst loading (S/C=4000), which was competitive with the activity of most effective noble metal catalysts for this reaction. The precise regulation of the enantioselectivity were ensured by a p–p interaction.<u></u></p>

scholarly journals Manganese-Catalyzed Asymmetric Hydrogenation of Quinolines Enabled by pi–pi Interaction

2020 ◽  
Author(s):  
Chenguang Liu ◽  
Mingyang Wang ◽  
Shihan Liu ◽  
Yujie Wang ◽  
Yong Peng ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Noble Metal ◽  
Asymmetric Hydrogenation ◽  
Catalyst Loading ◽  
Turnover Number ◽  
Noble Metal Catalysts ◽  
Wide Range ◽  
Metal Catalyzed ◽  
High Yields ◽  
Low Catalyst Loading

<p>The first example of non-noble metal-catalyzed asymmetric hydrogenation of aromatic <i>N</i>-heterocycles is reported. A new chiral pincer manganese catalyst showed outstanding catalytic activity in the asymmetric hydrogenation of a wide range of quinolines, affording high yields and excellent enantioselectivities (up to 97% <i>ee</i>). A turnover number of 3840 was reached at a low catalyst loading (S/C=4000), which was competitive with the activity of most effective noble metal catalysts for this reaction. The precise regulation of the enantioselectivity were ensured by a p–p interaction.<u></u></p>

Three-Component Synthesis of 4-Arylidene-3-alkylisoxazol-5(4H)-ones in the presence of potassium 2,5-dioxoimidazolidin-1-ide

2021 ◽  
Vol 25 ◽  
Author(s):  
Neda Reihani ◽  
Hamzeh Kiyani
Keyword(s):  
Ethylene Glycol ◽  
Ethyl Acetoacetate ◽  
Reaction Medium ◽  
Hydroxylamine Hydrochloride ◽  
Aromatic Aldehydes ◽  
Catalyst Loading ◽  
Efficient Synthesis ◽  
Current Process ◽  
High Yields ◽  
Low Catalyst Loading

: An efficient synthesis of 4-arylidene-3-alkylisoxazole-5(4H)-ones has been implemented via the three-component cyclocondensation of aryl(heteroaryl)aldehydes with hydroxylamine hydrochloride and β-ketoesters. The potassium 2,5-dioxoimidazolidin-1-ide has been introduced as the new organocatalyst to facilitate of this heterocyclization. In the current process, three starting materials, including substituted benzaldehydes/heterocyclic aromatic aldehydes, hydroxylamine hydrochloride, and ethyl acetoacetate/propyl acetoacetate/butyryl acetoacetate have been successfully used for the synthesize of the number of substituted isoxazole-5(4H)-ones in good to high yields in ethylene glycol as a green reaction medium at 80 ºC. The low catalyst loading is also a main advantage over the some reported catalysts.

Control of S.I. Engine Exhaust Emissions Using Non-Precious Catalyst (ZSM-5) Supported Bimetals and Noble Metals as Catalyst

2005 ◽  
Author(s):  
Bankim B. Ghosh ◽  
Prokash Chandra Roy ◽  
Mita Ghosh ◽  
Paritosh Bhattacharya ◽  
Rajsekhar Panua ◽  
...  
Keyword(s):  
Noble Metal ◽  
Noble Metals ◽  
Bimetallic Catalyst ◽  
Catalytic Converter ◽  
Exhaust Emissions ◽  
Metal Catalysts ◽  
Oxides Of Nitrogen ◽  
Noble Metal Catalysts ◽  
Maximum Reduction ◽  
Wide Range

Three Way Catalysts (TWC) are extensively used for simultaneous control of three principal automotive pollutants, namely carbon monoxide (CO), Oxides of nitrogen (NOx), and hydrocarbon (HC). Most of works on three way catalytic converter have been carried out with noble metals such as Platinum, Rhodium, and Iridium have been tried individually and in different combinations and proportions. Noble metal catalysts give very good performance of reduction of (NOx), CO and HC in the narrow range of stoichiometric Air Fuel ratio. Noble metals are costly and not abundantly available. These draw backs of the noble metal catalysts have inspired to search for the alternative catalysts, which will perform well over the wide range of A/F ratio and are economical and abundantly available. This paper discusses the processing of ZSM-5 to Cu-Ion- Exchanged ZSM-5, ZSM-5 supported Cu-Pt bimetallic catalyst and Cu-Rh bimetallic catalyst and placing them in a three staged converter to study the reduction efficiencies of exhaust emissions CO, NOx, and HC in a 800 cc Maruti S. I. Engine. The experiments are carried out at 1500 rpm, 17.6 A/F ratio, different catalyst bed temperatures and different engine loads 0%, 17.5%, 35%, 52.5%, and 70% of full load. The results achieved are the maximum reduction of CO 90% at 375 °C NOx 90% at 375 °C and HC 61% at 380 °C. The same engine was also run for Noble metal converter (NMC) (EURO-II) purchased from an authorized Maruti distributor and the maximum reduction achieved were CO 89% at 375° C, NOx 91% at 375° C, and HC 70% at 390° C comparable to Zeolite Catalytic Converter (ZCC).

scholarly journals Enantioselective Michael addition of 2-hydroxy-1,4-naphthoquinones to nitroalkenes catalyzed by binaphthyl-derived organocatalysts

2012 ◽  
Vol 8 ◽  
pp. 699-704 ◽  
Author(s):  
Saet Byeol Woo ◽  
Dae Young Kim
Keyword(s):  
Michael Addition ◽  
Catalyst Loading ◽  
High Yields ◽  
Low Catalyst Loading

The highly enantioselective Michael addition of 2-hydroxy-1,4-naphthoquinones to nitroalkenes, promoted by binaphthyl-modified chiral bifunctional organocatalysts is described. This reaction afforded the chiral functionalized naphthoquinones in high yields (81–95%) and excellent enantioselectivities (91–98% ee) under low catalyst loading (1 mol %).

Potassium Hydroxide Catalysed Intermolecular Aza-Michael Addition of 3-Cyanoindole to Aromatic Enones

Synlett ◽  
2017 ◽  
Vol 28 (10) ◽  
pp. 1227-1231 ◽  
Author(s):  
Jingya Yang ◽  
Tianyuan Li ◽  
Hongyan Zhou ◽  
Nana Li ◽  
Dongtai Xie ◽  
...  
Keyword(s):  
Reaction Temperature ◽  
Michael Addition ◽  
Potassium Hydroxide ◽  
Michael Reaction ◽  
Pharmaceutical Compounds ◽  
Catalyst Loading ◽  
Good Substrate ◽  
Substrate Tolerance ◽  
High Yields ◽  
Low Catalyst Loading

Indole is one of the utmost important heterocycles as it is an essential nucleus of many pharmaceutical compounds. Its aza-Michael reaction, however, is underdeveloped because of the moiety’s inherent characteristics. Here, a potassium hydroxide catalysed intermolecular aza-Michael reaction of 3-cyanoindole with aromatic enones is described. A variety of chalcone derivatives are well tolerated and afford the corresponding N-adducts in moderate to high yields. The use of a cheap catalyst, low catalyst loading, mild reaction temperature, and good substrate tolerance make this procedure a direct and facile method for the preparation of N1-functionalized indoles.

Highly Enantioselective Michael Addition of Cyclic Diketones to β,γ-Unsaturated α-Keto Esters Catalyzed by Squaramide Organocatalyst

Synthesis ◽  
2022 ◽  
Author(s):  
Zhi-Wei Ma ◽  
Chuan-Chuan Wang ◽  
Quan-Jian Lv ◽  
Xiao-Pei Chen ◽  
Ai-Qin Li ◽  
...  
Keyword(s):  
Michael Addition ◽  
Large Scale ◽  
Catalyst System ◽  
Catalyst Loading ◽  
Reaction Conditions ◽  
Keto Esters ◽  
Bicyclic Compounds ◽  
Asymmetric Michael Addition ◽  
High Yields ◽  
Low Catalyst Loading

AbstractA new tertiary amine-squaramide organocatalyst has been developed and applied to the asymmetric Michael addition of cyclic diketones to β,γ-unsaturated α-keto esters. The catalyst system performed well with a low catalyst loading of 1 mol% under mild reaction conditions. A series of synthetically and pharmaceutically useful chiral bicyclic compounds were obtained in high yields (up to 97%) with excellent enantioselectivities (up to 99 % ee). Furthermore, this catalytic system can be used efficiently in large-scale reactions with the yields and enantioselectivities being maintained.

scholarly journals Crucial aspects in the design of chirally modified noble metal catalysts for asymmetric hydrogenation of activated ketones

2015 ◽  
Vol 44 (21) ◽  
pp. 7449-7464 ◽  
Author(s):  
Alfons Baiker
Keyword(s):  
Noble Metal ◽  
Noble Metals ◽  
Asymmetric Hydrogenation ◽  
Metal Catalysts ◽  
Catalytic Systems ◽  
Noble Metal Catalysts ◽  
Heterogeneous Catalytic

This tutorial review analyzes the crucial aspects, which have to be considered in the development of heterogeneous catalytic systems based on chirally modified noble metals for asymmetric hydrogenation of activated ketones.

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