Tetranuclear titanium 7,7′‐modified binaphtholate cluster as a novel chiral Lewis acid catalyst

Abstract

Abstract 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. Chirality 13:541–544, 2001. © 2001 Wiley‐Liss, Inc.