Lewis Base Catalyzed, Sulfenium Ion Initiated Enantioselective, Spiroketalization Cascade

Kimberly M. Hilby, Scott E. Denmark

Research output: Contribution to journalArticlepeer-review


A Lewis base catalyzed, enantioselective sulfenocyclization of alkenes to afford [6,6]spiroketals has been developed. The method uses a chiral Lewis base catalyst with an electrophilic sulfur source to generate enantioenriched thiiranium ion with alkenes. Upon formation, the thiiranium ion is subsequently captured in a cascade-type reaction, wherein a ketone oxygen serves as the nucleophile to open the thiiranium ion and an alcohol provides the secondary cyclization to form biorelevant spiroketals. A variety of electron-rich and electron-neutral E-substituted styrenes form the desired spiroketals in good yields with excellent enantio- and diastereoselectivities. Alkyl-substituted and terminal alkenes participate in the cascade reaction, but with a limited scope compared to the styrenyl substrates. This method allows for rapid formation of highly substituted spiroketals in good yield and excellent enantioselectivity.

Original languageEnglish (US)
Pages (from-to)14250-14289
Number of pages40
JournalJournal of Organic Chemistry
Issue number21
StatePublished - Nov 5 2021

ASJC Scopus subject areas

  • Organic Chemistry


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