| 摘要 |
The present invention also relates to a novel impurity, (6-{2-[2-(6-{2-[2-(4-fluorophenyl)-5-isopropyl-3-phenyl-4-phenylcarbamoyl-pyrrol-1-yl]-ethyl}-2,2-dimethyl-[1,3]-dioxan-4-yl)-acetylamino]-ethyl}-2,2-dimethyl-[1,3]-dioxan-4-yl)-acetic acid tert-butyl ester, the compound of formula IV, having the following structure: The present invention also provides methods of preparing the compound of formula IV as well as methods of using the compound of formula IV as a reference marker and a reference standard. The present invention also provides an improved process for preparing (4R,cis)-6-[2-[3-phenyl-4-(phenyl-carbamoyl)-2-(4-fluorophenyl)-5-(1-methyl-ethyl)-pyrrole-1-yl]-2,2-dimethyl-[1,3]dioxane-4-yl-acetic acid-tertiary butyl ester, the compound of formula I, said process comprising the step of condensing 4-fluoro-alpha-[2-methyl-1-oxopropyl]-gamma-oxo-N,beta-diphenylbenzene butanamide, the compound of formula III, with (4R,Cis)-1,1-dimethylethyl-6-(2-aminoethyl)-2,2-dimethyl-1,3-dioxane-4-acetate, the compound of formula II, in the presence of a catalytic amount of an acid in the presence of a solvent system, preferably a binary solvent system, to obtain the desired compound (4R,cis)-6-[2-[3-phenyl-4-(phenyl-carbamoyl)-2-(4-fluorophenyl)-5-(1-methyl-ethyl)-pyrrole-1-yl]-2,2-dimethyl-[1,3]dioxane-4-yl-acetic acid-tertiary butyl ester.
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