Visible-Light-Driven Tandem Cyclization of o‑Hydroxyaryl Enaminones: Access to 3‑(α-Arylsulfonamido)trifluoroethyl Chromones

A visible-light-driven intermolecular tandem α-amidotrifluoroethylation/cyclization of enaminones using a previously unreported N-trifluoroethylaminopyridinium salt was achieved in the absence of transition metal catalysts or bases. Notable features of this synthetic method include mild conditions, high selectivity, excellent functional group compatibility, and satisfactory yields. Preliminary mechanistic studies indicate that the reaction proceeds via a radical pathway, involving an in situ generated N-trifluoroethyl radical, followed by a 1,2-H shift.

本研究利用此前尚未见报道的N-三氟乙基氨基吡啶鎓盐，在无需过渡金属催化剂与碱的条件下，实现了可见光驱动的烯胺酮分子间串联α-酰胺基三氟乙基化/环化反应。该合成方法具备鲜明优势：反应条件温和、选择性优异、官能团兼容性良好且收率可观。初步机理研究表明，该反应通过自由基路径进行，先生成原位产生的N-三氟乙基自由基，随后发生1,2-氢迁移。