Alpha-fluorotropinone immobilized on silica: a new stereoselective heterogeneous catalyst for epoxidation of alkenes with oxone.
The dioxirane-mediated epoxidation of alkenes in the presence of supported alpha-fluorotropinones 5 and 9 has been evaluated. The catalysts anchored onto silica supports 5 have shown comparable activity with respect to the homogeneous counterpart 10 and good stability on recycling. In the second part of this paper the enantiomerically enriched alpha-fluorotropinone 4 was anchored onto both mesoporous MCM-41 and amorphous KG-60 silicas. The chiral-supported catalysts promoted the stereoselective epoxidation of several trans-substituted and trisubstituted alkenes with ee values up to 80% and were perfectly reusable with the same performance for at least three catalytic cycles.
Sartori
Giovanni
G
Clean Synthetic Methodologies Group, Dipartimento di Chimica Organica e Industriale dell'Università, Parco Area delle Scienze 17A, I-43100 Parma, Italy. sartori@unipr.it
Armstrong
Alan
A
Maggi
Raimondo
R
Mazzacani
Alessandro
A
Sartorio
Raffaella
R
Bigi
Franca
F
Dominguez-Fernandez
Belen
B