Syntheses of Substituted α,β-Unsaturated δ-Lactams from N -Boc-2,4-dioxopiperidine.

A method for the syntheses of substituted α,β-unsaturated δ-lactams ( 2 ) from the commercially available compound N -Boc-2,4-dioxopiperidine ( 1 ) has been developed. The α-substituents were introduced by a reductive Knoevenagel condensation reaction, and the β-substituents were installed by palladium-catalyzed cross coupling reactions. More than 20 diverse examples were prepared in 2-3 steps. The synthesis was operationally simple, user-friendly, and easy to scale up.