We started to synthesize antitumor agent Taxol via a convergent and efficient route. We planned to prepare A-ring and C-ring fragments with perfect stereoselectivity, followed by their coupling and construction of the eight-membered ring for the total synthesis of Taxol. During these studies we found the unprecedented construction of the eight-membered ring via the intramolecular B-alkyl Suzuki-Miyaura coupling and the stereoselective construction of the A-ring via the intramolecular silicon-tethered nucleophilic addition. Although the remaining problem to be solved was to construct the trans-fused B,C-ring, we have succeeded to construct it by 1,4-addition of a cyanide ion and SN2' reduction of the allylic phosphonium salt. These studies will be reported.
