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 journalArticle

Abstract

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
Volume21
Issue number11
DOIs
Publication statusPublished - Jun 7 2019

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Thiourea
Protonation
thioureas
esters
Esters
catalysts
Betaine
Catalysts
Ketones
Stereoselectivity
betaines
leucine
Enantioselectivity
ketones
Experiments
2-amino-3,3-dimethylbutanoic acid

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry

Cite this

Enantioselective Protonation of Enol Esters with Bifunctional Phosphonium/Thiourea Catalysts. / Yamamoto, Eiji; Wakafuji, Kodai; Mori, Yusuke; Teshima, Gaku; Hidani, Yuki; Tokunaga, Makoto.

In: Organic Letters, Vol. 21, No. 11, 07.06.2019, p. 4030-4034.

Research output: Contribution to journalArticle

Yamamoto, Eiji ; Wakafuji, Kodai ; Mori, Yusuke ; Teshima, Gaku ; Hidani, Yuki ; Tokunaga, Makoto. / Enantioselective Protonation of Enol Esters with Bifunctional Phosphonium/Thiourea Catalysts. In: Organic Letters. 2019 ; Vol. 21, No. 11. pp. 4030-4034.
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