Heterogeneous asymmetric catalysis epoxidation

Ding and coworkers [58] have also reported the use of chiral self-supported BINOL-Zn catalysts for the heterogeneous asymmetric catalysis of epoxidation of... 

Obviously, the way to heterogeneous enantioselective catalysis is open when chiral ligands are introduced into the polymers. This idea was first proposed by Okamoto and Still (231). However, the first catalytic results were published by Cazaux and Caze (235). These authors use the asymmetric Mo(VI) complex (9) covalently bound to a cross-linked polystyrene resin for the enantioselective epoxidation of geraniol. Unfortunately, the enantiomeric excess obtained was low—far below that obtained with the Ti-tartrate catalyst (Section II,B). Moreover, the polymeric structure appeared to be unstable. 

Heterogenous metal tartrates were screened for their efficacy in the catalysis of the asymmetric ring opening of me o-2,3-disubstituted epoxides with thiols, aniline, and trimethylsilyl azide [72]. Whereas the enantioselectivity of Zn(II) tartrates is in the 15-85 % ee range, selectivity with the Mn(II), Fe(II), and Co(II) tartrates was lower (< 40 % ee). With Nugent s Zr(Of-Bu)4/C3-symmetric tetradentate ligand catalyst... 

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