Mild allylic defluorination of 3,3-difluorobut-1-ene derivative activated by a phenylsulfonyl group

4-Benzyloxy-3,3-difluoro-4-phenyl-2-phenylsulfonylbut-1-ene (3) underwent the allylic defluorination reaction with aryl- and alkylthiolate, and alkoxides without any additive reagents to give the monofluoroalkenes 4–5 in good yields. Reactions of 3 with various Grignard reagents such as alkyl-, aryl-, vinyl- and alkylethynylmagnesium bromides also provided the corresponding monofluoroalkenes 6 in good yields. Finally, compound 3 was reacted with t-butylamine at −45 °C for 1 h to afford the monofluoroalkene 9 in good yields.