合成路线1

A partial synthesis of Taxol starting from deacetyl Baccatin III (XI) has been developed: The starting compounds, the acid (I) and the silylated Baccatin III (II) have been obtained as follows: a) The reaction of 3(S)-amino-2(R)-hydroxy-3-phenylpropionic acid ethyl ester (VIII) with benzyloxycarbonyl chloride and Na2CO3 in ethyl or tert-butyl ether/water gives 3(S)-(benzyloxycarbonylamino)-2(R)-hydroxy-3-phenylpropionic acid ethyl ester (IX), which is condensed with benzyloxymethyl chloride by means of BuLi in THF yielding the fully protected ester (X). The hydrolysis of (X) with LiOH in ethanol/water affords the desired acid (I). b) The silylation of (deacetyl Baccatin III) (XI) with triethylsilyl chloride in pyridine gives the monosilylated deacetyl Baccatin III (XII), which is then acetylated with acetyl chloride in pyridine or BuLi in THF to afford the desired silylated Baccatin III (II).