The ortho metalation of N-(tert-butoxycarbonyl)-3, 4-difluoroaniline, with t-BuLi at− 78dgC in THF occurred regioselectively at C-2 position. The resulting lithiated species reacted with a variety of electrophiles to give 2-substituted-3, 4-difluoroanilines in good yields after hydrolysis. These compounds have been readily transformed into C-8 substituted fluoroquinolones. The nucleophilic substitution at C-7 by piperazines and the alkylation at ...
