Visible-light-promoted olefinic trifluoromethylation of enamides with CFSONa.

A visible-light-promoted olefinic C-H trifluoromethylation of enamides was developed by employing cheap and stable Langlois' reagent as the CF source. A series of β-CF enamides were obtained in moderate to good yields with high E-isomer selectivity under mild conditions. Preliminary mechanistic studies suggest that molecular oxygen acts as the terminal oxidant for this net oxidative process, and the E isomer selectivity could be well explained by a base-assisted deprotonation of the cation intermediate.