Application of diethyl ethynylphosphonate to the synthesis of 3‐phosphonylated β‐lactams via the Kinugasa reaction

Dedicated to Prof. Jacek Młochowski on the occasion of his 80th birthday.The easily available diethyl ethynylphosphonate reacts with diverse aldonitrones under Kinugasa reaction conditions at room temperature, providing 3‐phosphonylated β‐lactams in good yields. In all cases, the reaction led to the trans‐isomer exclusively. The trans‐configuration was assigned based on 1H‐NMR spectroscopic analysis.Authors acknowledge the National Science Center (PL-Cracow) for financial support (Grant OPUS–7 (UMO– 2014/13/B/ST5/04004))