A new class of bifunctional chiral phase transfer catalysts for highly enantioselective asymmetric epoxidation of α,β-unsaturated ketones at ambient temperature

2015 ◽  
Vol 409 ◽  
pp. 127-136 ◽  
Author(s):  
Veeramanoharan Ashokkumar ◽  
Rajendiran Balasaravanan ◽  
Velu Sadhasivam ◽  
Seenisultanmaideen Mehtob Jenofar ◽  
Ayyanar Siva
Keyword(s):  
Ambient Temperature ◽  
Phase Transfer ◽  
Asymmetric Epoxidation ◽  
Chiral Phase ◽  
Unsaturated Ketones ◽  
Phase Transfer Catalysts ◽  
New Class ◽  
Chiral Phase Transfer Catalysts

Ultrasonic assisted dimeric cinchona based chiral phase transfer catalysts for highly enanatioselective synthesis of epoxidation of α,β-unsaturated ketones

RSC Advances ◽  
2014 ◽  
Vol 4 (104) ◽  
pp. 60293-60299 ◽  
Author(s):  
Jayaraman Sivamani ◽  
Veeramanoharan Ashokkumar ◽  
Velu Sadhasivam ◽  
Kumaraguru Duraimurugan ◽  
Ayyanar Siva
Keyword(s):  
Ultrasonic Irradiation ◽  
Phase Transfer ◽  
Cinchona Alkaloids ◽  
Ammonium Bromide ◽  
Chiral Phase ◽  
Unsaturated Ketones ◽  
Phase Transfer Catalysts ◽  
Ultrasonic Assisted ◽  
Chiral Phase Transfer Catalysts ◽  
Enantioselective Epoxidation

New types of bis-quaternary ammonium bromide as chiral multisite phase transfer catalysts derived from cinchona alkaloids have been developed and evaluated for the enantioselective epoxidation of chalcones in the presence of lower concentrations of various oxidants, bases and ultrasonic irradiation conditions.

scholarly journals Studies in Asymmetric Epoxidation of Chalcone Using Quaternary Salts and Nonionic Surfactants Based on 6-Amino-6-deoxy-glucose as Chiral Phase Transfer Catalysts

2011 ◽  
Vol 8 (3) ◽  
pp. 1293-1297
Author(s):  
Lalit Sharma ◽  
Subhash Chander Sharma ◽  
Saroj
Keyword(s):  
Nonionic Surfactants ◽  
Phase Transfer ◽  
Enantiomeric Excess ◽  
Hydrocarbon Chain ◽  
Asymmetric Epoxidation ◽  
Chiral Phase ◽  
Phase Transfer Catalysts ◽  
Quaternary Salts ◽  
Chiral Phase Transfer Catalysts ◽  
Branched Chain

Quaternary salts and nonionic surfactants based on 6-amino-6-deoxy-glucose were explored as chiral phase transfer catalysts for the asymmetric epoxidation of chalcone. Quaternary salts used in the present study, were void of any branched chain or long hydrocarbon chain, whereas the sugar based nonionic surfactants have a long hexadecyl moiety as tail. It was observed that quaternary salts showed no activity as phase transfer catalysts but sugar based nonionic surfactants acted as chiral phase transfer catalysts. It was also revealed that hydrophilicity of the surfactant favors more yield whereas stereochemistry governs enantioselectivity. (6,6'-Hexadecylimino) bis(6-deoxy-1,2-O-isopropylidene-α-D-glucofuranose) was found to be the most suitable chiral phase transfer catalyst, resulting asymmetric epoxidation of chalcone with 90% yield and 16.5% enantiomeric excess (ee).

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