Synthesis of Amide Enol Carbamates and Carbonates through Cu(OTf)2‑Catalyzed Reactions of Ynamides with t‑Butyl Carbamates/Carbonates

A highly regioselective approach to access amide enol carbamates and carbonates 5a–5c′, 7a–7h, and 9 was developed through Cu­(OTf)2-catalyzed reactions of ynamides 4 with t-butyl carbamates 2 and 8 and t-butyl carbonates 6. Moreover, this strategy was successfully applied to generate amide enol carbamates 11a–11s and 14a–14f from imides 10 and 13 with ynamides through an N-Boc cleavage–addition ring-opening process. A range of substituents was amenable to this transformation, and the desired amide enol carbamates and carbonates were obtained in moderate to good yields.