Reaction of 4-Substituted 1-[(Difluoromethyl)sulfinyl]-2,3,4,5-tetrafluorobenzenes with Ammonia and Methylamine

The reaction of 4-X-substituted 1-[(difluoromethyl)sulfinyl]-2,3,5,6-tetrafluorobenzenes (X = CF3, H, OMe) with methylamine and ammonia in MeCN, Et2O, and hydrocarbons occurs involves nucleophilic substitution in position 2 of the substrate. The reaction time increases with increasing donor ability of substituent X in the series X = CF3 < H < OMe, as well as with decreasing solvent polarity. Further substitution of fluorine in position 6 of the substrate by methylamine is also possible, but requires a higher reaction temperature. The reaction of ammonia with 1-[(difluoromethyl)sulfinyl]-4-methoxy-2,3,5,6-tetrafluorobenzene is accompanied by partial demethylation to form 2-[(difluoromethyl)sulfinyl]-3,4,6-trifluoro-5-methoxy-N-methylaniline and 4-[(difluoromethyl)sulfinyl]-2,3,5,6-tetrafluorophenol.