Synthesis of (+)- and (−)-Phaselic Acid

Abstract

The syntheses of both enantiomers of phaselic acid (2-O-caffeoylmalate) are described. The previously unreported acetate-protected caffeic acid anhydride was used with appropriately protected malic acid derivatives as coupling partners to provide fully protected phaselic acid. Sequential unmasking of the protecting groups afforded phaselic acid in an acceptable overall yield.

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GRAPHICAL ABSTRACT

Keywords:

• 2-O-Caffeoyl-D-malate
• 2-O-caffeoyl-L-malate
• phaselic acid

ACKNOWLEDGMENTS

The author thanks Steve Burke and Alex Clemens of the University of Wisconsin–Madison Department of Chemistry for assistance in obtaining optical rotations and NMR spectra. Purchase of the Varian Mercury-300 NMR instrument in 2003 was funded through a grant from NSF, Award CHE-0342998 to the Department of Chemistry, University of Wisconsin–Madison. Purchase of the Waters LCT instrument in 2000 was partially funded by NSF Award CHE9974839 to the Department of Chemistry, University of Wisconsin–Madison. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.

Notes

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