The key intermediates (3) were prepared by
three routes. One route is the fluorination of acetophenones
(4) by electrophilic fluorinating reagents (route A). The sec-
ond route is the reaction of ethyl 2,2-difluoro-2-(substituted
thio)acetate (6) with phenyllithiums (route B), and the third
route is the reaction of a -chloro- a , a -difluoroacetophenone