A process for the preparation of crisaborole

Abstract

The present invention relates to a process for the preparation of crisaborole of formula (I): by preparing intermediates of formulas (II) and (III):

1 - 15 . (canceled) 
     
     
         16 . A process for the purification of Crisaborole which comprises dropwise addition of a 5:1 to 8:1 acetone:water mixture of the compound to water, followed by stirring at room temperature and filtration of the resulting product. 
     
     
         17 . A process according to claim  1  comprising the dropwise addition of a 7:1 acetone:water mixture. 
     
     
         18 . A process according to claim  1  wherein crisaborole of formula (I) 
       
         
           
           
               
               
           
         
         is obtained by: 
         a) converting compound of formula (II): 
       
       
         
           
           
               
               
           
         
         
           into compound of formula (III): 
         
       
       
         
           
           
               
               
           
         
         
           in the presence of a tri (C 1 -C 4 ) alkyl borate and a (C 4 -C 6 )alkyl lithium or aryl lithium and subsequent acidification of the reaction medium; and 
         
         b) converting the resulting compound of formula (III) into Crisaborole of formula (I) by catalytic hydrogenation.