Hemilabile amidomonophosphine ligand-rhodium(I) complex-catalyzed asymmetric 1,4-addition of arylboronic acids to cycloalkenones.
The asymmetric 1,4-addition reaction of arylboronic acids with cycloalkenones was catalyzed by 1 mol % of an amidomonophosphine-rhodium(I) catalyst in a 10:1 mixture of 1,4-dioxane and water at 100 degrees C, affording 3-arylcycloalkanones in reasonably high enantioselectivity and high yields. It was revealed by NMR, IR, and X-ray spectroscopies that this bidentate amidomonophosphine behaves as a hemilabile ligand that contains a hard donor site in addition to the soft donor in a molecule. Phosphorus atom strongly bonds to rhodium(I), and the amide carbonyl oxygen is coordinatively labile. The reaction efficacy of phenylboronic acid with cyclopent-2-en-1-one was significantly dependent on the possibility of coordination of the amide carbonyl oxygen to rhodium(I).
Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
Masami
M
Kuriyama
Kazushige
K
Nagai
Ken-Ichi
K
Yamada
Yoshinao
Y
Miwa
Tooru
T
Taga
Kiyoshi
K
Tomioka