| abstract |
The invention relates to novel processes for the preparation of high-purity roflumilast. The process involves reacting the anion of 4 - armino -3,5 dichloropyridine (I), with an activated derivative of 3-cyclopropylmethoxy-4-difluoromethoxybenzoic acid (II), characterized in that the molar ratio of the employed anion of 4-amino-3,5 dichloropyridine to the activated derivative of 3-cyclopropylmethoxy-4-difluoromethoxybenzoic acid is at least 1.5 and at most 3, preferably at least 1.8 and at most 2.7 particularly preferably at least 2 and at most 2.5 and very particularly preferably 2.2 |