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.本研究报道了一种由成本低廉且易于获取的螺旋手性环戊二烯（PCCP）催化剂介导的对映选择性Pictet-Spengler型反应。该反应方法在温和反应条件下即可进行，可合成一类新型手性4,5-二氢吡咯并[1,2-a]喹喔啉（DHPQs），这类化合物因分子内氢键的存在而表现出更强的抗芳构化能力。此外，该合成策略具有广泛的底物兼容性，且展现出优异的合成通用性。