Synthesis of new chiral bis(isoxazoline) ligands containing spiro[5.5]undecane skeleton.
New chiral bis(isoxazoline) ligands bearing a spiro[5.5]undecane skeleton were designed and synthesized in five steps from diethyl malonate (3). These ligands showed a coordinating ability to Cu(II) as chiral ligands. A complex of (+)-(M*,S*,R*)-[5.5]-SPRIX 2b and Cu(OTf)(2) catalyzed the conjugate addition of diethyl-zinc to 2-cyclohexenone (8) to give (S)-3-ethyl-cyclohexanone (9) in 93% yield with 54% ee.
Arai
Midori A
MA
The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, Japan.
Kuraishi
Minori
M
Arai
Takayoshi
T
Sasai
Hiroaki
H