A Direct Carbometallation-Stereoselective Cycloaddition-Ring Closing Metathesis Route to the Tricyclic ABC Core of Taxoids

Abstract The synthesis of the tricyclic ABC ring-system of Taxol ® (paclitaxel) is described. This direct route involves sequential reactions employing the carbometallation of a propargyl alcohol, followed by a CIS-alkene tether controlled stereoselective intramolecular Diels-Alder reaction to generate the AB-ring system and ring closing metathesis (RCM) of the pendant allyl substituents to construct the C ring.