Process for the preparation of n-(3,5-dichloropyrid-4-yl)-4-difluoromethoxy-8-methanesulfonamido-dibenzo[b,d]furan-1-carboxamide

Abstract

The present invention relates to a method of preparing N-(3,5-dichloropyrid-4-yl)-4-difluoromethoxy-8-methanesulfonamido-dibenzo[b,d]furan-1-carboxamide and pharmaceutically acceptable salts thereof, such as its sodium salt, and novel intermediate compounds useful in the synthesis of the aforementioned compound.

1 - 56 . (canceled) 
   
   
       57 . N-(3,5-dichloropyrid-4-yl)-4-difluoromethoxy-8-methanesulfonamido-dibenzo[b,d]furan-1-carboxamide or a pharmaceutically acceptable salt thereof containing:
 (a) 4-cyclopentyloxy-3-(4′-nitro-2′-bromophenoxy)benzaldehyde (C);   (b) a compound of the formula   
     
       
         
         
             
             
         
       
     
     where
 R 1  is hydrogen or a substituted or unsubstituted C 1-6  alkyl, and 
 PG is an aldehyde protecting group; or 
 
     (c) p-nitrophenyl-4-difluoromethoxy-8-nitro dibenzo[b,d]furan-1-carboxylic acid ester (H), in an amount greater than 0% but less than 0.15%. 
   
   
       58 . N-(3,5-dichloropyrid-4-yl)-4-difluoromethoxy-8-methanesulfonamido-dibenzo[b,d]furan-1-carboxamide of claim  49 , wherein the compound of formula E-I is 1-{[(4-methylphenyl)imino]methyl}-8-nitro-dibenzo [b,d] furan-4-ol (E 1 ) or 1-{[(4-methylphenyl)imino]methyl}-4-difluoromethoxy-8-nitro-dibenzo [b,d] furan (E 2 ).