The detailed synthesis and characterization of (-)-11-(triethoxysilyl)-10,11-dihydrocinchonidine (4), a starting material for the immobilization of (-)- cinchonidine on silica based supports, is described. Compound 4 together with its precursors 9-O-(trimethylsilyl)cinchonidine (2) and 9-O-(trimethylsilyl)-11-(triethoxysilyl)-10,11-dihydrocinchonidine (3) were employed as chiral modifiers in the hydrogenation of a prochiral diketone, 1-phenylpropane-1,2-dione, over a heterogeneous Pt/Al2O3 catalyst using cinchonidine (1) as a reference modifier. The unexpected enhancement of ee induced by 4, demonstrating the positive effect of distal modifier substitution, is discussed in the light of molecular modeling and NMR studies.
|Number of pages||8|
|Journal||Journal of the Chemical Society, Perkin Transactions 1|
|Publication status||Published - 2002|
|MoE publication type||A1 Journal article-refereed|