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Cooperative Tertiary Amine/Palladium-Catalyzed Sequential [4 + 3] Cyclization/[1,3]-Rearrangement for Stereoselective Synthesis of Spiro [Methylenecyclopentane-1,3′-oxindolines]

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journal contribution
posted on 2022-12-23, 21:13 authored by Yue-You Chen, Chen-Dong Zhou, Xing-Tong Li, Ting-You Yang, Wen-Yong Han, Nan-Wei Wan, Yong-Zheng Chen, Bao-Dong Cui
A cooperative tertiary amine/palladium-catalyzed sequential reaction process, proceeding via a [4 + 3] cyclization of isatin-derived Morita-Baylis-Hillman Expansion (MBH) carbonates and tert-butyl 2-(hydroxymethyl)­allyl carbonates followed by a [1,3]-rearrangement, has been found and developed. A range of structurally diverse spiro­[methylene cyclopentane-1,3′-oxindolines] bearing two adjacent β,γ-acyl quaternary carbon stereocenters, which are difficult to obtain by conventional strategies, were obtained in good yields. Further synthetic utility of this protocol is highlighted by its excellent regio- and stereocontrol as well as the large-scale synthesis and diverse functional transformations of the synthetic compounds. Moreover, the control experiments probably established the plausible mechanism for this sequential [4 + 3] cyclization/[1,3]-rearrangement process.