BigPatents India

The present invention provides a process for preparing pure warfarin acid comprising: (a) preparing coumarol by condensing 4-hydroxy coumarin with benzal acetone in methanol in the presence of a catalyst such as herein described; (b) hydrolyzing the coumarol obtained in step (a) above in the presence of acetic acid mixture to obtain warfarin acetate; (c) subjecting the warfarin acetate to further hydrolysis using an alkali solution followed by treatment with a polar solvent that is immiscible in water to separate the aqueous phase, followed by treating the aqueous phase with aqueous acid to precipitate warfarin in high purity. No. of Pages : 16 No. of Claims : 15