Poly(Ethylene Glycol)‐Supported Proline: A Versatile Catalyst for the Enantioselective Aldol and Iminoaldol Reactions

摘要: (2S,4R)-4-Hydroxyproline has been anchored to the monomethyl ether of poly(ethylene glycol), MW 5000, by means a succinate spacer afford soluble, polymer-supported catalyst (PEG-Pro) for enantioselective aldol and iminoaldol condensation reactions. This organic can be considered as minimalistic version type I aldolase enzyme, with polymer chain replacing enzyme's peptide backbone, proline residue acting active site. In presence PEG-Pro (0.25–0.35 mol equiv.), acetone reacted enolizable non-enolizable aldehydes imines β-ketols β-aminoketones in good yield high enantiomeric excess (ee), comparable those obtained using non-supported derivatives catalysts. Extension PEG-Pro-promoted hydroxyacetone donor opened an access synthetically relevant anti-α,β-dihydroxyketones syn-α-hydroxy-β-aminoketones, that were moderate yields, diastereo- enantioselectivity. Exploiting its solubility properties, was easily recovered recycled promote all above-mentioned reactions, occurred slowly diminishing yields but virtually unchanged ee's.