Method for producing 2,2-difluoroethylamine derivative by amide hydrogenation

A process for preparing a 2,2-difluoroethylamine derivative, comprising reducing a 2,2-difluoroacetamide derivative of formula (IV) to the corresponding 2,2-difluoroethylamine derivative of formula (III):

• by using a reducing agent which is selected from LiAlH4, LiAlH(O-tert-butyl)3, LiAlH(O-methyl)3, NaAlEt2H2, borohydrides, BH3, 9-borabicyclo[3.3.1]nonane, disiamylborane, AlH3, DIBAL-H (AlH(isobutyl)2), or hydrides of silicon hydrides of the formula
• H—Si—R3
• where R—is H, optionally substituted alkyl, optionally substituted phenyl or chlorine;
• and
• where the A radical in formulae (III) and (IV) is 6-fluoropyrid-3-yl, 6-chloropyrid-3-yl, 6-bromopyrid-3-yl, 6-methylpyrid-3-yl, 6-trifluoromethylpyrid-3-yl, 6-trifluoromethoxypyrid-3-yl, 6-chloro-1,4-pyridazin-3-yl, 6-methyl-1,4-pyridazin-3-yl, 2-chloro-1,3-thiazol-5-yl or 2-methyl-1,3-thiazol-5-yl, 2-chloropyrimidin-5-yl, 2-trifluoromethylpyrimidin-5-yl, 5,6-difluoropyrid-3-yl, 5-chloro-6-fluoropyrid-3-yl, 5-bromo-6-fluoropyrid-3-yl, 5-iodo-6-fluoropyrid-3-yl, 5-fluoro-6-chloropyrid-3-yl, 5,6-dichloropyrid-3-yl, 5-bromo-6-chloropyrid-3-yl, 5-iodo-6-chloropyrid-3-yl, 5-fluoro-6-bromopyrid-3-yl, 5-chloro-6-bromopyrid-3-yl, 5,6-dibromopyrid-3-yl, 5-fluoro-6-iodopyrid-3-yl, 5-chloro-6-iodopyrid-3-yl, 5-bromo-6-iodopyrid-3-yl, 5-methyl-6-fluoropyrid-3-yl, 5-methyl-6-chloropyrid-3-yl, 5-methyl-6-bromopyrid-3-yl, 5-methyl-6-iodopyrid-3-yl, 5-difluoromethyl-6-fluoropyrid-3-yl, 5-difluoromethyl-6-chloropyrid-3-yl, 5-difluoromethyl-6-bromopyrid-3-yl or 5-difluoromethyl-6-iodopyrid-3-yl.