![N-Heterocyclic Carbene-Catalyzed Formal [3+3] Annulation of Alkynoic Acid Esters with Indolin-3-ones: Access to Functionalized Pyrano[3,2-b]indol-2-ones]()
N-Heterocyclic Carbene-Catalyzed Formal [3+3] Annulation of Alkynoic Acid Esters with Indolin-3-ones: Access to Functionalized Pyrano[3,2-b]indol-2-onesDu, Ding; Sun, Kewen; Jin, Shiyi; Fang, Shuaishuai; Ma, Rui; Zhang, Xinmiao; Gao, Maoyu; Zhang, Wanqi; Lu, Tao · Organic Chemistry Frontiers · 2019