Post-synthesis organo-sylanation of mesostructured FSM-16 for chiral Mn(III) salen catalyst anchoring

The mesoporous FSM-16 material was chemically modified with two spacers, namely 3-aminopropyltriethoxysilane (APTES) or 4-triethoxysilylaniline (TESA) to anchor the Jacobsen catalyst derivative (CAT 1) through coordinative bond of the amine group of the spacer to the metal centre. The resulting heterogeneous catalysts were tested in the asymmetric epoxidation at low temperature, of three alkenes – styrene, α-methyl-styrene and 6-cyano-2,2-dimethylchromene – using m-CPBA/NMO as oxygen source. The nitrogen elemental analysis showed that a much higher amount of APTES than TESA was anchored onto the FSM-16. The FSM-16 material with grafted APTES has the double amount of CAT 1 anchored than the FSM-16 material with grafted TESA. The pore size distribution analysis of the nitrogen adsorption isotherms shows that TESA, APTES and CAT 1 catalyst are anchored inside the pores of the FSM-16 material. Under the same experimental condition in the asymmetric epoxidation of styrene, α-methyl-styrene and 6-cyano-2,2-dimethylchromene, the APTES based materials showed better activity in both, conversion and enantiomeric excess, than TESA based materials.