Tetranuclear titanium 7,7'-modified binaphtholate cluster as a novel chiral Lewis acid catalyst.
Chiral tetranuclear Ti cluster, a cubic structure constituted of four Ti atoms and OHs, and six (R)-binaphthols (BINOL) bridged two Ti atoms as ligands, is shown to be a novel chiral Lewis acid catalyst for the [2+3] cycloaddition reaction with nitrones. The chiral Ti clusters with 7,7'-substituted (R)-BINOL ligands was synthesized to give enhanced enantiomeric excesses up to 78% ee.
Mikami
K
K
Department of Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan. kmikami@o.cc.titech.ac.jp
Ueki
M
M
Matsumoto
Y
Y
Terada
M
M