Dissemin is shutting down on January 1st, 2025

Published in

Wiley, Chemistry - A European Journal, 20(9), p. 4887-4899, 2003

DOI: 10.1002/chem.200304966

Wiley-VCH Verlag, ChemInform, 6(35), 2004

DOI: 10.1002/chin.200406165

Links

Tools

Export citation

Search in Google Scholar

Stereoselective Aldol Additions Catalyzed by Dihydroxyacetone Phosphate-Dependent Aldolases in Emulsion Systems: Preparation and Structural Characterization of Linear and Cyclic Iminopolyols from Aminoaldehydes

This paper is available in a repository.
This paper is available in a repository.

Full text: Download

Green circle
Preprint: archiving allowed
Orange circle
Postprint: archiving restricted
Red circle
Published version: archiving forbidden
Data provided by SHERPA/RoMEO

Abstract

The potential of dihydroxyacetone phosphate (DHAP)-dependent aldolases to catalyze stereoselective aldol additions is, in many instances, limited by the solubility of the acceptor aldehyde in aqueous/co-solvent mixtures. Herein, we demonstrate the efficiency of emulsion systems as reaction media for the class I fructose-1,6-bisphosphate aldolase (RAMA) and class II recombinant rhamnulose-1-phosphate aldolase from E. coli (RhuA)-catalyzed aldol addition between DHAP and N-benzyloxycarbonyl (N-Cbz) aminoaldehydes. The use of emulsions improved the RAMA-catalyzed aldol conversions by three to tenfold relative to those in conventional DMF/water mixtures. RhuA was more reactive than RAMA towards the N-Cbz aminoaldehydes regardless of the reaction medium. With (S)- or (R)-Cbz-alaninal, RAMA exhibited preference for the R enantiomer, while RhuA had no enantiomeric discrimination. The linear N-Cbz aminopolyols thus obtained were submitted to catalytic intramolecular reductive amination to afford the corresponding iminocyclitols. This reaction was diastereoselective in all cases examined; the face selectivity was controlled by the stereochemistry of the newly formed hydroxyl group originating from the aldehyde. Characterization of the resulting iminocyclitols allowed the assessment of the diastereoselectivity of the enzymatic aldol reactions with respect to the N-protected aminoaldehyde. RAMA formed single diastereoisomers from N-Cbz-glycinal and from both enantiomers of N-Cbz-alaninal, while 14 % of the epimeric product was observed from N-Cbz-3-aminopropanal. Diastereoselectivity from RhuA was lower than that observed from RAMA. Interestingly, a single diastereoisomer was formed from (S)-Cbz-alaninal, whereas only a 34 % diastereomeric excess was observed from its enantiomer (i.e., (R)-Cbz-alaninal).