Patent ID: 8552194

Claim:
A process for the preparation of substituted quinoline-3-carboxamide compound of formula I: wherein R is selected from methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec,-butyl and allyl; R 1 is selected from methyl, ethyl, n-propyl, iso-propyl, methoxy, ethoxy, methylthio, ethylthio, n-propylthio, methylsulphinyl, ethylsulphinyl, fluoro, chloro, bromo, trifluoromethyl, difluoromethoxy and trifluoromethoxy; R 2 is hydrogen; or R 1 and R 2 together can be methylenedioxy, ethylenedioxy and isopropylidenedioxy; R 3 is selected from hydrogen, methyl, ethyl, n-propyl, iso-propyl, methoxy, ethoxy, fluoro, chloro, bromo, trifluoromethyl, difluoromethoxy and trifluoromethoxy; and R 4 is selected from hydrogen, fluoro and chloro, with the proviso that R 4 is selected from fluoro and chloro only when R 3 is selected from fluoro and chloro; comprising: reacting a quinoline-3-carboxylic acid derivative of formula II: wherein R 1 and R 2 are as defined in formula I; with an aniline derivative of formula III: wherein R, R 3 and R 4 are as defined in formula I; in the presence of a coupling agent in a solvent to provide a substantially pure compound of formula I and optionally converting the compound of formula I obtained into a pharmaceutically acceptable salt thereof; wherein the coupling agent is selected from the group consisting of dichlorotriphenyl phosphorane, phosphorous oxychloride, O-benzotriazole-N,N,N′,N′-tetramethyl-uronium-hexafluoro-phosphate (HBTU), and combinations comprising one or more of the foregoing coupling agents.