Zirconium phosphates methyl and/or phenyl phosphonates-supported l-proline have been prepared as amorphous solids by precipitation of (4R)-4-(phosphonooxy) -l-proline, methyl and/or phenyl phosphonic acid with ZrOCl2. The supported l-proline catalysts were tested on the direct asymmetric aldol addition of cyclohexanone to p-nitrobenzaldehyde in DMF/H2O (9:1) and in sole water. The hydrophobic groups on solid surface favor reagents' diffusion toward proline chiral moiety increasing the catalytic activity of supported l-proline. High diastereoselectivity (anti/syn up to 94:6) and high enantiomeric excess up to 97% have been obtained.
Supported L-proline on Zirconium Phosphates Methyl and/or Phenyl Phosphonates as Heterogeneous Organocatalysts for Direct Asymmetric Aldol Addition.
LANARI, DANIELA;ORRU', MARA;PIERMATTI, Oriana;PIZZO, Ferdinando;VACCARO, Luigi
2011
Abstract
Zirconium phosphates methyl and/or phenyl phosphonates-supported l-proline have been prepared as amorphous solids by precipitation of (4R)-4-(phosphonooxy) -l-proline, methyl and/or phenyl phosphonic acid with ZrOCl2. The supported l-proline catalysts were tested on the direct asymmetric aldol addition of cyclohexanone to p-nitrobenzaldehyde in DMF/H2O (9:1) and in sole water. The hydrophobic groups on solid surface favor reagents' diffusion toward proline chiral moiety increasing the catalytic activity of supported l-proline. High diastereoselectivity (anti/syn up to 94:6) and high enantiomeric excess up to 97% have been obtained.File in questo prodotto:
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