In the presence of a catalytic amount of a zirconium-bis(binaphthol)methane complex (5), Mannich-typereactions of aldimines with silylenolates proceeded smoothly to afford the corresponding adducts in high yields with high enantiomeric excesses. (R)-(R)-Bis(3-BINOL)methane 6, that was prepared by linking two binaphthols, was shown to be very effective in these reactions.
Linking BINOL: C2-symmetric ligands for investigations on asymmetric catalysis
作者:Erasmus M Vogl、Shigeki Matsunaga、Motomu Kanai、Takehiko Iida、Masakatsu Shibasaki
DOI:10.1016/s0040-4039(98)01756-0
日期:1998.10
The synthesis of new C2-symmetric chiral ligands consisting of two binaphthol units linked by a short bridge is described. These ligands can be used for investigating catalytic asymmetric reactions which utilize BINOL or related ligands as was demonstrated for the ring opening reaction of cyclohexene oxide with 4-methoxyphenol.