π-Lewis-Base-Catalyzed Asymmetric Vinylogous Umpolung Reactions of Cyclopentadienones and Tropone

Xing Xing Yang, Ru Jie Yan, Guang Yao Ran, Chen Chen, Jing Fei Yue, Xiao Yan, Qin Ouyang, Wei Du, Ying Chun Chen

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)

Abstract

We disclose that the carbonates of 4-hydroxy-2-cyclopentenones can form π-allylpalladium-based 1,2-carbodipoles, which isomerize to interesting η2-Pd0-cyclopentadienone complexes. Compared with the labile parent cyclopentadienone, the HOMO energy of the related η2-complex was significantly raised via the back-bonding of Pd0 as a π-Lewis base, rendering the uncoordinated C=C bond an electron-richer dienophile in inverse-electron-demand aza-Diels–Alder-type reactions with diverse 1-azadienes. The vinylogous (aza)Morita–Baylis–Hillman or cross Rauhut–Currier addition to (imine)carbonyls or activated alkenes, respectively, was also realized to afford chiral [4+2] or [2+2] cycloadducts, respectively, after trapping the re-generated π-allylpalladium species. New C1-symmetric ligands from simple chiral sources were developed, exhibiting high stereoselectivity even with racemic substrates via an unusual dynamic kinetic resolution process. Besides, tropone could be similarly activated by a Pd0 complex.

Original languageEnglish
Pages (from-to)26762-26768
Number of pages7
JournalAngewandte Chemie - International Edition
Volume60
Issue number51
DOIs
Publication statusPublished - 13 Dec 2021
Externally publishedYes

Keywords

  • cyclopentadienone
  • HOMO activation
  • tropone
  • umpolung
  • π-Lewis base catalysis

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