Asymmetric Synthesis of Spirocyclopentane Oxindoles <i>via</i> [2+3] Annulation with 2‐(2‐Oxoindolin‐3‐yl)malononitriles as 1,2‐Carbon Bisnucleophiles
Yue‐Yan Ai, Dong‐Ai Li, Li Guo, Heping Li, Xiang‐Hong He, Xue‐Ju Fu, Yuting Wang, Gu Zhan, Bo Han
Abstract
Abstract Carbon bisnucleophiles are important building blocks in organic synthesis and have widespread applications in the construction of carbocyclic compounds. Among them, 1,2‐carbon bisnucleophile has been much less explored. Herein, we developed a [2+3] annulation of 2‐(2‐oxoindolin‐3‐yl)malononitrile with 2‐nitroallylic acetates, where 2‐(2‐oxoindolin‐3‐yl)malononitrile served as a new type of 1,2‐carbon bisnucleophile. Remarkably, the annulation reaction exhibits exclusive chemo‐ and regioselectivity. A Michael addition/S N 2 mechanism was proposed to avoid the “anti‐Baldwin” cyclization. This stereoselective strategy provides a facile synthetic route for a new series of spirocyclopentane oxindole derivatives containing three stereogenic centers. magnified image