Enantioselective electrochemical oxidation of enol acetates using a chiral supporting electrolyte.
Anodic oxidation of 1-acetoxy-3,4-dihydronaphthalene (1) and alpha-acetoxy-beta-alkylstyrenes (3) at -78 degrees C in a mixed solvent of acetonitrile (CH(3)CN), tetrahydrofuran (THF), and acetic acid (AcOH) containing (S)-tetraethylammonium camphorsulfonate as a chiral supporting electrolyte brought about enantioselective formation of the corresponding 2-acetoxy-1-tetralones (2) and (R)-2-acetoxy-1-phenyl-1-alkanone (4) with maximum enantiomeric excess (ee) of 44% and 21%, respectively. Introduction of a 7-methoxy group into 1 and increase in bulkiness of a beta-alkyl group in 3 resulted in improvement of enantioselectivity of the reactions.
Maekawa
Hirofumi
H
Department of Chemistry, Nagaoka University of Technology, Nagaoka, Niigata, Japan.
Itoh
Kotaro
K
Goda
Satoshi
S
Nishiguchi
Ikuzo
I