Rhodium-catalyzed asymmetric 1,4-addition of aryltitanium reagents generating chiral titanium enolates: isolation as silyl enol ethers.
The addition of aryltitanium triisopropoxide (ArTi(OPr-i )3) to alpha,beta-unsaturated ketones proceeded with high enantioselectivity (94-99.8% ee) in the presence of 3 mol % of [Rh(OH)((S )-binap)]2 in THF at 20 degrees C to give high yields of the titanium enolates as 1,4-addition products. The titanium enolates were converted into silyl enol ethers by treatment with chlorotrimethylsilane and lithium isopropoxide.
Hayashi
Tamio
T
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan. thayashi@kuhem.kyoto-u.ac.jp
Tokunaga
Norihito
N
Yoshida
Kazuhiro
K
Han
Jin Wook
JW