Synthesis of screening substrates for the directed evolution of sialic acid aldolase: towards tailored enzymes for the preparation of influenza A sialidase inhibitor analogues.

Abstract

The stereoselective synthesis of two epimeric screening substrates, (4R, 5R, 6R)- and (4S, 5R, 6R)-6-dipropylcarbamoyl-2-oxo-4,5,6-trihydroxy-hexanoic acid, for the directed evolution of sialic acid aldolase is described. The complementary methods relied on stereoselective indium-mediated additions of ethyl alpha-bromomethyl acrylate to functionalised aldehydes. With an alpha-hydroxy aldehyde, (2R, 3R)-2,3-dihydroxy-4-oxo butanoic acid dipropylamide, the addition was chelation controlled, and the syn product, (6R, 5R, 4S)-6-dipropylcarbamoyl-2-methylidene-4,5,6-trihydroxy-hexanoic acid ethyl ester, was obtained. In contrast, the stereochemical outcome of the addition to (2R, 3R)-N,N-dipropyl-2,3-O-isopropylidene-4-oxobutyramide was consistent with Felkin-Anh control, and the anti adduct, (4R, 5R, 6R)-6-dipropylcarbamoyl-2-methylidene-4-hydroxy-5,6-O-isopropylidene-hexanoic acid ethyl ester, was the major product. Ozonolysis and deprotection gave the screening substrates as mixtures of furanose and pyranose forms, in good yields.

• Authors: Thomas Woodhall, Gavin Williams, Alan Berry, Adam Nelson
• Journal: Organic & biomolecular chemistry (Org Biomol Chem) Vol. 3 Issue 9 Pg. 1795-800 (May 07 2005) ISSN: 1477-0520 [Print] England
• PMID: 15858666 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Enzyme Inhibitors
• Neuraminidase
• Oxo-Acid-Lyases
• N-acetylneuraminate lyase

Topics

• Directed Molecular Evolution
• Enzyme Inhibitors (pharmacology)
• Influenza A virus (enzymology)
• Models, Molecular
• Neuraminidase (antagonists & inhibitors)
• Oxo-Acid-Lyases (genetics, metabolism)
• Substrate Specificity