Practical One‐Pot Synthesis of Cyclic Conjugated Amides From Ketones

Conjugated amides are valuable building blocks in organic synthesis; however, general access to cyclic conjugated amides remains limited, restricting their broader use in method development and complex molecule synthesis. Herein, we report a practical one‐pot synthesis of cyclic conjugated amides directly from readily available ketones. The transformation employs bromoform, an amine nucleophile, and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) and is proposed to proceed through carbene‐mediated homologation followed by in situ trapping of an acyl halide intermediate. A range of cyclic ketones and primary and secondary amines are converted into the corresponding conjugated amides in moderate to very good yields, including substrates bearing protected heterocycles, ether functionality, and alkyl or aryl substituents. The method also provides access to selected linear conjugated amides from acyclic ketones, including 1,1‐disubstituted derivatives.