合成路线1

A new method for the synthesis of the docetaxel side-chain has been reported: The esterification of (S)-phenylglycine (I) with SOCl2 and methanol gives the corresponding methyl ester (II), which is acylated with tert-butoxycarbonyl anhydride to the tert-butoxycarbonyl derivative (III). The reduction of (III) with dibutylaluminum hydride (DIBAL) in toluene yields the corresponding aldehyde (IV), which is condensed with 2-(trimethylsilyl)thiazole (V) by means of tetrabutylammonium fluoride (TBAF) to afford the (1R,2S)-N-[2-hydroxy-1-phenyl-2-(2-thiazolyl)ethyl]carbamic acid tert-butyl ester (VI) with 88% enantiomeric purity. The cyclization of (VI) with 2,2-dimethoxypropane (VII) catalyzed by camphosulfonic acid (CSA) gives (4S,5R)-3-(tert-butoxycarbonyl)-2,3-dimethyl-4-phenyl-5-(2-thiazolyl)ox azolidine (VIII), which is treated with methyl trifluoromethanesulfonate to afford (4S,5R)-3-(tert-butoxycarbonyl)-2,2-dimethyl-4-phenyloxazolidine-5-carb aldehyde (IX). Finally, this compound is oxidized with KMnO4 in tert-butanol/aqueous potassium phosphate buffer to yield the corresponding carboxylic acid, the (4S,5R)-3-(tert-butoxycarbonyl)-2,2-dimethyl-4-phenyloxazolidine-5-carb oxylic acid (X), the side-chain of taxotere suitably protected.