Synthesis of [3″‐3H]taxol and [13‐3H]taxol1

Abstract
7‐Trietylsilylbaccatin III (11) was coupled with cis‐1‐benzoyl‐3‐triethylsiloxy‐4‐(3′‐bromophenyl)azetidin‐2‐one. Hydrolysis of the silyl groups gave 3″‐bromotaxol which was reduced with tritium gas to give[3″‐3H]taxol with specific activity of 19.3 Ci mmol. Reduction of 7‐triethylsilyl‐13‐oxobaccatin III with [3H]borane‐tetrahydrofuran complex gave 7‐triethylsilyl[13‐3H]baccatin III (17). Coupling of 17 with cis‐3‐triethylsiloxy‐4‐phenyl‐(3R,4S)‐azetidin‐2‐one and hydrolysis gave [13‐3H]taxol with specific activity of 1.66 Ci/mmol.
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