Base-Mediated Intramolecular Cyclization of α‑Nitroethylallenic Esters as a Synthetic Route to 5‑Hydroxy-3-pyrrolin-2-ones

An unprecedented Cs2CO3-mediated intramolecular
cyclization/rearrangement cascade that transforms α-nitroethylallenic
esters to functionalized pyrrolin-2-ones has been uncovered. This
reaction provides a new and practical approach for the synthesis of
medicinally privileged 5-hydroxy-3-pyrrolin-2-ones under mild conditions.
The broad potential of this new method was demonstrated by an efficient
Au/Ag-catalyzed heteroarylation of 5-hydroxy-3-pyrrolin-2-ones employing
electron-rich heteroarenes to furnish heteroaryl-lactam derivatives.