Biphasic enantioselective olefin epoxidation using Tropos dibenzoazepinium catalysts.
Several novel chiral iminium TRISPHAT [tris(tetrachlorobenzenediolato)phosphate(V)] salts combining a diphenylazepinium core, chiral exocyclic appendages, and lipophilic counterions have been prepared and tested in biphasic enantioselective olefin epoxidation conditions. Interestingly, the iminium salts derived from commercially available (S)- or (R)-1,2,2-trimethylpropylamine can display efficiency similar to those made from L-acetonamine. Variable-temperature NMR spectroscopy (VT-NMR) and circular dichroism (CD) experiments were performed in search of a correlation between good enantioselectivity in the products and high diastereomeric control of the biphenyl axial chirality of the catalysts.
Vachon
Jérôme
J
Département de Chimie Organique, Université de Genève, quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland.
Pérollier
Céline
C
Monchaud
David
D
Marsol
Claire
C
Ditrich
Klaus
K
Lacour
Jérôme
J