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PreprintCC BY-NC-NDChemRxiv

Intramolecular Alkene Protonation Enables Stereoconvergent Catalysis Through Tertiary Carbenium Ions

  • Jin Won Lee1,2
  • Hyojae Jung1,2
  • Hayoung Song1,2
  • Injoo Seo1,2
  • Do Hyun Ryu1,2
  1. 1Department of Chemistry
  2. 2Sungkyunkwan University
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Abstract

Enantioselective trapping of tertiary carbenium ions is often complicated by competing E1 elimination. Here, we show that a chiral oxazaborolidinium ion catalyst promotes ground-state intramolecular proton transfer from a phenolic OH group to an adjacent alkene, generating a catalyst-associated tertiary carbenium ion for enantioselective trapping. This activation mode allows alkenes formed by E1 elimination to regenerate reactive cations during the stereoconvergent conversion of racemic tertiary alcohols. Hydride and carbon trapping afford enantioenriched diarylalkanes and products bearing acyclic all-carbon quaternary stereocenters in up to 99% yield and 99% ee. Experimental and computational studies support competition between direct cation trapping and elimination followed by alkene protonation, with the balance depending on nucleophile reactivity. These findings establish intramolecular alkene protonation as a strategy for incorporating elimination into productive asymmetric catalysis.

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Cite

BibTeXRIS
BibTeX
@misc{lee2026intramolecular,
  title = {{Intramolecular Alkene Protonation Enables Stereoconvergent Catalysis Through Tertiary Carbenium Ions}},
  author = {Jin Won Lee and Hyojae Jung and Hayoung Song and Injoo Seo and Do Hyun Ryu},
  howpublished = {ChemRxiv},
  year = {2026},
  month = sep,
  doi = {10.26434/chemrxiv.15008939/v1},
  url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008939/v1},
  note = {CC BY-NC-ND},
}
RIS
TY  - UNPB
TI  - Intramolecular Alkene Protonation Enables Stereoconvergent Catalysis Through Tertiary Carbenium Ions
AU  - Jin Won Lee
AU  - Hyojae Jung
AU  - Hayoung Song
AU  - Injoo Seo
AU  - Do Hyun Ryu
PY  - 2026
DA  - 2026/09/16
PB  - ChemRxiv
DO  - 10.26434/chemrxiv.15008939/v1
UR  - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008939/v1
AB  - Enantioselective trapping of tertiary carbenium ions is often complicated by competing E1 elimination. Here, we show that a chiral oxazaborolidinium ion catalyst promotes ground-state intramolecular proton transfer from a phenolic OH group to an adjacent alkene, generating a catalyst-associated tertiary carbenium ion for enantioselective trapping. This activation mode allows alkenes formed by E1 elimination to regenerate reactive cations during the stereoconvergent conversion of racemic tertiary alcohols. Hydride and carbon trapping afford enantioenriched diarylalkanes and products bearing acyclic all-carbon quaternary stereocenters in up to 99% yield and 99% ee. Experimental and computational studies support competition between direct cation trapping and elimination followed by alkene protonation, with the balance depending on nucleophile reactivity. These findings establish intramolecular alkene protonation as a strategy for incorporating elimination into productive asymmetric catalysis.
ER  -