合成路线1

合成路线2

Darifenacin can be obtained by three related ways: 1) The decarboxylation of (2S,4R)-4-hydroxypyrrolidine-2-carboxylic acid (I) by heating at 154 C in cyclohexanol/2-cyclohexenone gives 3(R)-hydroxypyrrolidine (II), which is N-tosylated with p-toluenesulfonyl chloride and pyridine yielding (III). The reaction of (III) with methyl p-toluenesulfonate, triphenylphosphine and diethyl azodicarboxylate (DEAD) in THF affords 1-tosyl-3(S)-(tosyloxy)pyrrolidine (IV), which is condensed with 2,2-diphenylacetonitrile (V) by means of NaH in refluxing toluene to give 2,2-diphenyl-2-[1-(p-toluenesulfonyloxy)pyrrolidin-2(S)-yl]acetonitrile (VI). Elimination of the tosyl group of (VI) with HBr and phenol in refluxing water yields 2,2-diphenyl-2-[2(S)-pyrrolidinyl]acetonitrile (VII), which by treatment with 95% H2SO4 at 100 C is converted into the corresponding acetamide (VIII). The condensation of (VIII) with 5-(chloroacetyl)-2,3-dihydrobenzofuran (IX) by means of potassium carbonate in industrial methylated spirits affords the ketonic amide (X), which is finally reduced with H2 over Pd/C in acetic acid. The intermediate 5-(chloroacetyl)-2,3-dihydrobenzofuran (IX) has been obtained by Friedel-Crafts condensation of 2,3-dihydrobenzofuran (XI) with chloroacetyl chloride by means of AlCl3 in dichloromethane. 3) The condensation of 5-(2-bromoethyl)benzofuran (XV), with the previously obtained acetamide (VIII) by means of K2CO3 in refluxing acetonitrile affords the condensation product (XVI), which is hydrogenated with H2 over Pd/C in hot acetic acid.