Department of Chemistry , University of Calcutta, University College of Science , 92, A. P. C. Road , Kolkata , West Bengal 700009 , India.
J Org Chem. 2019 Jan 4;84(1):42-52. doi: 10.1021/acs.joc.8b01503. Epub 2018 Dec 18.
The N-heterocycle carbene (NHC)-catalyzed dual Stetter cascade reaction is discovered through coupling of β-nitrostyrene with phthalaldehyde under mild conditions to furnish valuable aryl-naphthoquinones. The generality of the new reaction is validated through the development of a C-C and O-C bond forming Stetter cascade reaction using salicylaldehydes to obtain functionalized dihydroisoflavanones. The mild NHC organocatalysis is successfully employed for the construction of optically pure sugar-based naphthoquinones and dihydroisoflavanones. Herein, NHC is found as a unique and powerful organocatalyst to construct homoatomic C-C cross-coupling, heteroatomic O-C bond formation, and cascade cyclization utilizing NO as a leaving group at ambient temperature. A mechanistic pathway of the new metal-free catalysis is predicted on the basis of our ESI-MS study of the ongoing reaction and literature.
N-杂环卡宾（NHC）催化的双重Stetter 级联反应是通过β-硝基苯乙烯与邻苯二醛在温和条件下偶联发现的，可得到有价值的芳基萘醌。通过发展使用水杨醛的 C-C 和 O-C 键形成的 Stetter 级联反应，验证了新反应的通用性，从而获得了功能化的二氢异黄酮。温和的 NHC 有机催化成功地用于构建具有光学纯糖基萘醌和二氢异黄酮。在此，NHC 被发现是一种独特而强大的有机催化剂，可在环境温度下利用 NO 作为离去基团构建同原子 C-C 交叉偶联、杂原子 O-C 键形成和级联环化。根据我们对正在进行的反应和文献的 ESI-MS 研究，预测了新的无金属催化的反应机理途径。
