The nature of catalytic asymmetric dihydroxylation (AD), in particular the problem of ligand leaching from insoluble polymer-bound (IPB) Cinchona alkaloid derivatives, has been investigated. An upper limit to the amount of dissolved ligand, and methods for its evaluation, which assure a basically heterogeneous character of the observed AD reaction, are presented. A new copolymer architecture, which meets the established stability requirements and allows the highly enantioselective (87-99 % ee) IPB-AD of representative alkene substrates, is also described.
Asymmetric Dihydroxylation with Recoverable Cinchona Alkaloid Derivatives: A Warning Note and an Improved, Insoluble Polymer-Bound Ligand Architecture
MANDOLI, ALESSANDRO;PINI, DARIO;SALVADORI, PIERO
2005-01-01
Abstract
The nature of catalytic asymmetric dihydroxylation (AD), in particular the problem of ligand leaching from insoluble polymer-bound (IPB) Cinchona alkaloid derivatives, has been investigated. An upper limit to the amount of dissolved ligand, and methods for its evaluation, which assure a basically heterogeneous character of the observed AD reaction, are presented. A new copolymer architecture, which meets the established stability requirements and allows the highly enantioselective (87-99 % ee) IPB-AD of representative alkene substrates, is also described.File in questo prodotto:
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