Synthesis of a novel C-10 spiro-epoxide of paclitaxel

New analogues of paclitaxel (1a, active constituent of Taxol®) were synthesized containing an epoxide at the C-10 position. The introduction of the epoxide was carried out by selective removal of the C10-acetate followed by protection of the C2′- and C7-hydroxyl groups. After oxidation to yield a ketone at the C10-position, this intermediate was reacted with dimethylsulfonium ylide. Deprotection and further manipulations provide the C10-spiro epoxide of paclitaxel (1b) and the corresponding C7-MOM ether (1c).