Asymmetric epoxidation with a photoactivated [Ru(salen)] complex.
(Nitrosyl)(salen)ruthenium(II) complex 1 was found to serve as an efficient catalyst for the epoxidation of conjugated olefins under photoirradiation, with 2,6-dichloropyridine N-oxide (2) or tetramethylpyrazine N,N'-dioxide as a stoichiometric oxidant. High enantioselectivity was achieved irrespective of the substitution pattern of olefins. The choice of solvent depends on stability of the resulting epoxides: high enantioselectivity is generally observed in the reaction with ethereal solvents, but use of benzene is recommended when the resulting epoxides are acid-sensitive.
Nakata
K
K
Department of Chemistry, Faculty of Science, Graduate School, Kyushu University 33, Fukuoka, Japan. katsuscc@mbox.nc.kyushu-u.ac.jp
Takeda
T
T
Mihara
J
J
Hamada
T
T
Irie
R
R
Katsuki
T
T