Recursive anionic γ'-spiro-annulation of cyclic vinylogous esters with 2-vinylbenzoates
Chia-Chen Chien1, Grace Victoria Govada1, Li-Ching Shen1
1Department of Applied Chemistry and Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, 1001 University Road, Hsinchu City 30010, Taiwan. yenkuwu@nycu.edu.tw.
None:
We report a γ'-selective anionic cascade spiroannulation between cyclic vinylogous esters (CVEs) and 2-vinylbenzoates. This transformation proceeds with high γ'-selectivity, enabling CVEs to function as γ',γ'-dianionic equivalents while engaging 2-vinylbenzoates as an unconventional 1,5-dielectrophilic partner. Mechanistically, this behavior is attributed to two sequential deprotonations at the γ'-position of the CVE, enabling a recursive anionic activation process. The reaction is efficiently promoted by KOtBu in the presence of a Cu(I) salt in DMF under thermal conditions. This method enables rapid construction of densely functionalized spirocarbocyclic scaffolds with high structural complexity.
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