Enantioselective epoxidation of styrene with TBHP catalyzed by bis(oxazoline)–vanadyl–laponite materials

Abstract

Bis(oxazoline)-vanadyl complexes have been prepared from two precursors, VO(acac)2 and VOSO4, and immobilized on laponite by cation exchange. These catalysts have been tested in the enantioselective epoxidation of styrene with TBHP. The catalytic activities are always much higher in the case of VO(acac)2. The ligand improves the catalytic activity, with similar or slightly better selectivity to styrene oxide (up to 42%) and up to 63% ee in solution. Laponite support is also beneficial in most cases, with selectivities to styrene oxide up to 60%. Moderate enantioselectivities are obtained, better with VOSO4 solids, up to 72% ee.