Is There Another Common Intermediate beyond Chorismic Acid in the

J. Org. Chem. 1994,59, 720-728

720

Articles Is There Another Common Intermediate beyond Chorismic Acid in the Shikimate Pathway? Synthesis of trans-34(l-Carboxyvinyl)oxy]-6-hydroxycyclohexa1,4-diene-1-carboxylic Acid Karen Marie Mattia and Bruce Ganem' Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301 Received October 19, 1 9 9 9

As part of a search for mechanistic commonalities uniting the three chorismate-processingenzymes of anthranilate, PABA, and isochorismate biosynthesis, the title compound 9a, a highly labile allylic isomer of chorismic acid, was prepared by total synthesis. The synthetic route featured a new, Lewis-acid promoted opening of epoxides by diselenides leading to trans-hydroxy selenides. This remarkable reaction obviates the need to handle unpleasant selenols and simplifies the usual twostep anionic process involving in situ generation of alkali metal selenides. Diene 9a underwent rapid acid-catalyzed aromatization and [3,3]-sigmatropic rearrangement. Claisen rearrangement of 9a (tip