SYNTHESIS OF [3''-H-3]TAXOL AND [13-H-3]TAXOL

7-Triethylsilylbaccatin III (11) was coupled with 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''-H-3]taxol w ith specific activity of 19.3 Ci mmol. Reduction of 7-triethylsilyl-13 -oxobaccatin III with [H-3]borane-tetrahydrofuran complex gave 7-triet hylsilyl[13-H-3]baccatin III (17). Coupling of 17 with s-3-triethylsil oxy-4-phenyl-(3R,4S)-azetidin-2-one and hydrolysis gave [13-H-3]taxol with specific activity of 1.66 Ci/mmol.