Enantioselective Pictet–Spengler-Type Reaction via a Helically Chiral Anion as an Access to 4,5-Dihydropyrrolo[1,2-a]quinoxaline Scaffolds

We report an enantioselective Pictet-Spengler-type reaction enabled by a cost-effective and readily available helically chiral cyclopentadiene (PCCP) catalyst. This methodology, conducted under mild reaction conditions, facilitates the synthesis of a novel class of chiral 4,5-dihydropyrrolo[1,2-a]quinoxalines (DHPQs) characterized by enhanced resistance to aromatization due to intramolecular hydrogen bonding. Additionally, the protocol exhibits broad substrate compatibility and demonstrates significant synthetic versatility.