An aqueous reaction medium, based on a surfactant solution of diethyltetradecylamine N-oxide (AOE-14), was developed for the enantioselective epoxidation of 1,2-dihydronaphthalene and of various cis-b-alkyl styrenes with increasing hydrophobicity, using bleach as oxidant and the Jacobsen chiral (salen)Mn(III) as catalyst. AOE-14 is able to both solubilize all reactants inwater and bind the metal of the salen complex acting as coligand. Its use leads to good yields (>75%) and to ee values ranging from 75% up to 91% even in the case of cis-b-alkyl styrenes where lower cis/trans epoxide ratios are observed. The ratio of surfactant/substrate used is 1:1 or 4:1, much lower than those generally used in the literature.
Enantioselective Epoxidation of Alkenes Catalized by (Salen)Mn(III) in Aqueous Surfactant Systems
BRINCHI, Lucia;GERMANI, Raimondo;SAVELLI, Gianfranco;
2008
Abstract
An aqueous reaction medium, based on a surfactant solution of diethyltetradecylamine N-oxide (AOE-14), was developed for the enantioselective epoxidation of 1,2-dihydronaphthalene and of various cis-b-alkyl styrenes with increasing hydrophobicity, using bleach as oxidant and the Jacobsen chiral (salen)Mn(III) as catalyst. AOE-14 is able to both solubilize all reactants inwater and bind the metal of the salen complex acting as coligand. Its use leads to good yields (>75%) and to ee values ranging from 75% up to 91% even in the case of cis-b-alkyl styrenes where lower cis/trans epoxide ratios are observed. The ratio of surfactant/substrate used is 1:1 or 4:1, much lower than those generally used in the literature.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
