Viability of a [2 + 2 + 1] Hetero-Pauson–Khand Cycloaddition Strategy toward Securinega Alkaloids: Synthesis of the BCD-Ring Core of Securinine and Related Alkaloids

Preliminary results related to the development of [2 + 2 + 1]-oxa-hetero-Pauson–Khand cycloaddition strategy toward the Securinega alkaloids are reported. The critical tricyclic BCD-ring core was assembled in only nine linear steps from cheap 4-hydroxy-l-proline. The study provides valuable insight into the scope of a rare hetero-Pauson–Khand reaction, a powerful tool for the rapid construction of butenolide-containing natural products.