Method of preparation of anticancer taxanes using 3-[(substituted-2-trialkylsilyl)ethoxy-carbonyl]-5-oxazolidine carboxylic acids

Abstract

This invention relates to a process for preparation of taxanes comprising subjecting 7,10-diprotected intermediates 7-O-(2-haloacyl)baccatin III 6c or 7,10-O-di-(2-haloacyl)-10-deacetylbaccatin III 6b to a step of coupling with (4S,5R)-3-[(2-alkyl/aryl-2-trialkylsilyl)ethoxy-carbonyl]-4-aryl-2-substituted-1,3-oxazolidine-5-carboxylic acid 1 in the presence of a condensation agent, an activating agent and an aromatic hydrocarbon to obtain 7-O-[2-(haloacyl)]-13-[(4S,5R)-4-aryl-2-substituted-3(2-unsubstituted/substituted-2-trialkylsilyl)-ethoxycarbonyl-1,3-oxazolidinyl-5-carbonyl]baccatin III 7a or 7,10-di-O [2-(haloacyl)]-13-[(4S,5R)-4-aryl-2-substituted-3-(2-unsubstituted/substituted-2-trialkylsilyl)ethoxy-carbonyl-1,3-oxazolidinyl-5-carbonyl]-10-deacetylbaccatin III 7b;treating the coupled products 7-O-[2-(haloacyl)]-13-[(4S,5R)-4-aryl-2-substituted-3-(2-substituted-2-trialkylsilyl)ethoxy-carbonyl-1,3-oxazolidinyl-5-carbonyl]baccatin III 7a or 7,10-di-O-[2[(haloacyl)]-13-[(4S,5R)-4-aryl-2-substituted-3-(2-substituted-2-trialkylsilyl)ethoxycarbonyl-1,3-oxazolidinyl-5-carbonyl]-10-deacetylbaccatin III 7b with tetraalkylammonium halide in a haloalkane to obtain free amine of structure 8;treating free amine 8 with acid chloride or acid anhydride in the presence of a base in a heterogeneous phase to obtain the intermediates of structure 9;subjecting the intermediates of compound 9 to the deprotection of 2-haloacyl group under mild alkaline condition at −20 to +40° C. for 6-24 h in the presence of ammonia or aliphatic amines or aromatic amines or their combination to obtain paclitaxel or docetaxel.