合成路线1

A new partial synthesis of taxol has been described: The esterification of (1S,2R)-2-phenylcyclohexanol (I) with benzyloxyacetyl chloride (II) gives the corresponding chiral ester (III), which is deprotected by hydrogenolysis to the hydroxy ester (IV). Silylation of (IV) with triisopropylsilyl chloride affords the silylated ester (V), which is cyclized with trimethylsilylbenzaldimine (VI) [obtained from benzaldehyde (VII) and hexamethyldisilazane (HMSA)] by means of butyllithium in THF giving (3R,4S)-3-(triisopropylsilyloxy)-4-phenylazetidin-2-one (VIII). The deprotection of (VIII) with tetrabutylammonium fluoride affords (3R,4S)-3-hydroxy-4-phenylazetidin-2-one (IX), which is treated with ethyl vinyl ether to give the 1-ethoxyethyl ether (X). The benzoylation of (X) with benzoyl chloride (XI) by means of dimethylaminopyridine and triethylamine yields (3R,4S)-1-benzoyl-3-(1-ethoxyethoxy)-4-phenylazetidin-2-one (XII), which is condensed with 7-O-(triethylsilyl)baccatin III (XIII) by means of NaH in THF, affording 2'-O-(1-ethoxyethyl)-7-O-(triethylsilyl)taxol (XIV). Finally, this compound is deprotected with HCl in ethanol.

合成路线2

A new synthesis of paclitaxel starting from baccatin III has been described: The cyclocondensation of the Oppolzer's chiral auxiliary esterified with silylated glycolic acid (I) with benzaldehyde trimethylsilylimine (II) by means of lithium diisopropylamide (LDA) in THF gives (3R,4S)-3-(tert-butyldimethylsilyloxy)-4-phenylazetidin-2-one (III), which is benzoylated with benzoyl chloride and triethylamine/dimethylaminopyridine (DMAP) in dichloromethane, yielding (3R,4S)-1-benzoyl-3-(tert-butyldimethylsilyloxy)-4-phenylazetidin-2-one (IV). The condensation of (IV) with 7-O-(triethylsilyl)baccatin III (V) by means of NaH in THF affords silylated paclitaxel (VI), which is finally deprotected with HF in pyridine.

合成路线3