Transition-Metal-Free β‑C–H Bond Carbonylation of Enamides or Amides with a Trifluoromethyl Group as CO Surrogate for the Synthesis of 1,3-Oxazin-6-ones

A cascade
β-C–H bond trifluoromethylation/C­(sp3)–F
bond activation/hydrolysis reaction of enamides
with Togni’s reagent has been disclosed. This formal C–H
bond carbonylation reaction utilizes the CF3 group as a
CO surrogate to provide an efficient approach to 1,3-oxazin-6-ones
in satisfactory yields. Furthermore, CF3-containing 1,3-oxazin-6-ones
could also be accessed using this method by using alkenyl N-ethylamides involving the functionalization of one Csp2–H, one Csp3–H, one Csp2–H, and three Csp3–F bonds. The broad substrate
scope of this method enables access to synthetically or pharmaceutically
important compounds, which are difficult to access by known methods.