Synthesis of 6α‐Hydroxypaclitaxel, the Major Human Metabolite of Paclitaxel.

Abstract 6α-Hydroxypaclitaxel, the major human metabolite of paclitaxel, was synthesized via epimerization of 6α-hydroxy-7-epipaclitaxel, which was prepared from paclitaxel in four steps in high yield. Various epimerization conditions were investigated, and the optimum conditions using DBU in xylenes afforded 80–88% isolated yield based on unrecovered starting material, along with 4-deacetyl analogs as minor products. The stereochemistry of paclitaxel 6,7-epoxide was revised in the course of this work.