Synthesis of Cyclopropyl Taxane Analogs via Sequential Diels-Alder Reactions

摘要

The tandem Diels—Alder cycloaddition is a valuable method for the construction of linearly fused tricyclic ring systems as well as the tricyclic framework of taxol, 1 (Scheme 1). We have recently demonstrated that cycloaddition of bis-diene 2 and bis-dienophile 3 leads to the formation of 5, via 4, in excellent yield. While the synthesis of the taxane ring system in two chemical steps from simple acyclic precursors underscores the utility of this methodology in organic synthesis, this construction does not address several critical issues in taxane synthesis, including the establishment of the angularly methylated trans-B/C ring fusion of the taxane ring system.