Base-mediated [4+2] annulation of electron-deficient nitrobenzoheterocycles and α, α-dicyanoalkenes in water: Facile access to structurally diverse functionalized dibenzoheterocyclic compounds. Issue 17 (24th April 2020)

• Record Type: Journal Article
• Authors: Zhuo, Jun-Rui; Quan, Bao-Xue; Zhao, Jian-Qiang; Zhang, Ming-Liang; Chen, Yong-Zheng; Zhang, Xiao-Mei; Yuan, Wei-Cheng
• Is Part Of: Tetrahedron. Volume 76:Issue 17(2020)
• Publication Date: 2020-04-24
• Subjects: [4+2] annulation -- Tandem reaction -- 2-Nitrobenzofurans -- Heterocyclic compounds -- Vinylogous Michael addition; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2020.131115
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: A base-mediated [4 + 2] annulation of 2-nitrobenzofurans, 2-nitrobenzothiophenes, 3-nitrobenzothiophenes, and 3-nitroindoles with α, α -dicyanoalkenes for the synthesis of structurally diverse dibenzoheterocyclic compounds was developed. The reaction proceeded smoothly via a tandem vinylogous Michael addition/cyclization/tautomerization/elimination process in water with cesium carbonate as base, affording a wide range of dibenzofurans, dibenzothiophenes and carbazoles in good to high yields. The synthetic potential of the methodology was demonstrated by the scale-up experiment and versatile transformations of the products. The optical property of the polyheterocyclic aromatic products was also preliminarily investigated. Graphical abstract: Image 1 Highlights: An efficient [4+2] annulation of nitrobenzoheterocycles and α, α -dicyanoalkenes for the synthesis of polycyclic heterocycles. The eco-friendly [4+2] annulation reaction proceeded smoothly with water as the single solvent.