In an alternative procedure, paclitaxel (VII) was sequentially protected at the 2?hydroxyl with tert-butyldimethylsilyl chloride and then at the 7-hydroxyl with triethylsilyl chloride, yielding the disilylated derivative (VIII). Selective hydrolysis of the C-2 benzoate and the C-4 acetate esters of (VIII) with Triton B afforded the triol (IX). Protection of the C-1 and C-2 hydroxy groups of (IX) with carbonyldiimidazole gave the 1,2-cyclic carbonate derivative (X). Subsequent treatment of (X) with methyl chloroformate and lithium bis(trimethylsilyl)amide introduced the 4-O-methoxycarbonyl group to furnish (XI). Opening of the cyclic carbonate group of (XI) with phenyllithium produced the benzoate ester (XII). The silyl protecting groups of (XII) were then removed by means of HF-pyridine.

The silyl-protected 4-deacetyl baccatin (I) was deprotonated with lithium bis(trimethylsilyl) amide and then condensed with methyl chloroformate to produce carbonate (II). Desilylation of (II) using HF in pyridine afforded triol (III), which was selectively resilylated at the 7-hydroxyl group to furnish (IV). Attachment of the C-13 side-chain of (IV) was achieved by treatment with lactam (V) and lithium bis(trimethylsilyl)amide, yielding ester (VI). Finally, the silyl protecting groups of (VI) were removed by treatment with HF in pyridine.