2114-32-1Relevant academic research and scientific papers
Planar- and central-chiral N,O-[2.2]paracyclophane ligands: Non-linear-like effects and activity
Lauterwasser, Frank,Vanderheiden, Sylvia,Braese, Stefan
, p. 443 - 448 (2006)
The non-linear-like effect (NLLE), activity, temperature dependence, and kinetics of hydroxy-[2.2]paracyclophane ketimine ligands have been investigated with the 1,2-addition reaction of diethylzinc to cyclohexanecarbaldehyde. A linear correlation between the enantiomeric excess of AHPC ketimine ligands bearing a phenylethyl side group and the product was observed with 0.5 mol% of catalyst loading. On increasing the catalyst loading to 4 mol%, a precipitate of the inactive heterochiral species was formed and resulted in a positive non-linear-like effect. The enantiomeric ratio was found to have linear temperature dependence.
Catalysts for asymmetric addition of organozinc reagents to aldehydes and method for preparation
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, (2008/06/13)
Novel chiral aminoalcohol catalysts and methods for their preparation are provided. The first catalyst is prepared via selective hydrogenation of one of two benzene rings in a precursor. The aminoalcohol promotes the asymmetric addition of organozinc reagents to aldehydes to afford optically active alcohols or their esters. The second catalyst is prepared by selective dialkylation of 3-exo-aminoisoborneol with a 2-haloethyl ether. The aminoalcohol promotes the addition of organozinc reagents to aliphatic aldehydes containing a β-branch with greatly enhanced enantioselectivity relative to DAIB.
