NMR spectroscopic and theoretical evidence of cinchona alkaloid– ketopantolactone complex formation in aprotic solvents: Implications for the mechanism of Pt-catalyzed enantioselective hydrogenation of activated ketones

2007 ◽  
Vol 246 (2) ◽  
pp. 266-276 ◽  
Author(s):  
T MARTINEK ◽  
T VARGA ◽  
F FULOP ◽  
M BARTOK
Keyword(s):  
Complex Formation ◽  
Enantioselective Hydrogenation ◽  
Cinchona Alkaloid ◽  
Aprotic Solvents ◽  
Theoretical Evidence ◽  
Pt Catalyzed

Kinetic Analysis of Enantioselective Hydrogenation of 2,3-(E)-Diarylpropenoic Acids over a Chiral Cinchona Alkaloid-Modified Pd/C Catalyst

2020 ◽  
Vol 93 (1) ◽  
pp. 163-175 ◽  
Author(s):  
Bokeun Kim ◽  
Makoto Nakatsuji ◽  
Takuya Mameda ◽  
Takeshi Kubota ◽  
Morifumi Fujita ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Enantioselective Hydrogenation ◽  
Cinchona Alkaloid

Host–Guest interaction of pesticide bifenox with cyclodextrin molecules. An electrochemical study

2009 ◽  
Vol 74 (11-12) ◽  
pp. 1647-1664 ◽  
Author(s):  
Magdaléna Hromadová ◽  
Romana Sokolová ◽  
Lubomír Pospíšil ◽  
Štěpánka Lachmanová ◽  
Nicolangelo Fanelli ◽  
...  
Keyword(s):  
Complex Formation ◽  
Anion Radical ◽  
Formation Constants ◽  
Aprotic Solvents ◽  
Reduction Wave ◽  
Nitroaromatic Compound ◽  
Complex Formation Constants ◽  
Oh Groups ◽  
Stable Anion ◽  
Main Factor

The reduction of nitroaromatic compound bifenox (methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate) was studied in aprotic solvents in the absence or presence of cyclodextrin (CD) molecules of different cavity sizes. βCD and γCD form complexes with bifenox in DMSO with the complex formation constants (5 ± 2) × 102 M–1 [βCD–bifenox] and (3 ± 1) × 102 M–1 [γCD–bifenox], respectively. Bifenox yields a relatively stable anion radical in dimethyl sulfoxide, which is further reduced at more negative potentials by an overall addition of three electrons and four protons to the corresponding phenylhydroxylamine. In the presence of βCD the first reduction wave of bifenox becomes irreversible, it is shifted towards more positive potentials and the uptake of more than one electron is observed (up to four electrons during the exhaustive electrolysis). The first reduction wave of bifenox is not affected by the addition of glucose confirming that a simple availability of protons from the OH groups is not the main factor in further transformation of anion radical in the presence of βCD. The complex formation with βCD facilitates the protonation and additionally protects the molecule from disintegration into 2,4-dichlorophenol. A yield of 2,4-dichlorophenol decreases in the order βCD, γCD and αCD, respectively.

Enantioselective Hydrogenation of Trifluoromethylcyclohexyl Ketone on Cinchona Alkaloid Modified Pt-Alumina Catalyst

2004 ◽  
Vol 97 (1/2) ◽  
pp. 65-70 ◽  
Author(s):  
Károly Felföldi ◽  
Tibor Varga ◽  
Péter Forgó ◽  
Mihály Bartók
Keyword(s):  
Enantioselective Hydrogenation ◽  
Cinchona Alkaloid ◽  
Alumina Catalyst
Sign in / Sign up

Export Citation Format

Share Document