Highly Stereoselective Synthesis of β‐Enaminones From β‐Oxo‐Amides and Aryl Ethers via Carbon–Carbon Bond Formation

Highly stereoselective synthesis of β‐enaminones has been achieved from β‐oxoamides and aryl ethers via electrophilic activation strategy. The significant feature of this transformation is using combined hexaphenyloxodiphosphonium triflate (Hendrickson reagent) and triflic anhydride (Tf ₂ O). Moreover, the NMR investigations have demonstrated that the activation of β‐oxoamides exhibited very high chemoselectivity. Namely, Hendrickson reagent preferentially reacts with the acyl group of β‐oxoamides and Tf ₂ O activates the amide group of the substrates. The readily available starting materials, mild reaction conditions, high stereoselectivity, and wide range of synthetic potential of products make this protocol much attractive for academic research and practical applications.