Enantioselective Protonation of Enol Esters with Bifunctional Phosphonium/Thiourea Catalysts

Eiji Yamamoto, Kodai Wakafuji, Yusuke Mori, Gaku Teshima, Yuki Hidani, Makoto Tokunaga

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Bifunctional phosphonium/thioureas derived from tert-leucine behaved as highly selective catalysts for enantioselective protonation of enol esters, providing α-chiral ketones in yields of up to 99% with high enantioselectivities (up to 98.5:1.5 er). Control experiments clarified that a bulky tert-butyl group and phosphonium and thiourea moieties were necessary to achieve such high stereoselectivity. In addition, mechanistic investigations indicated the catalyst was converted to the corresponding betaine species, which served as a monomolecular catalyst.

Original languageEnglish
Pages (from-to)4030-4034
Number of pages5
JournalOrganic letters
Issue number11
Publication statusPublished - Jun 7 2019

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry


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