Remarkable Differences in Reactivity between Benzothiazoline and Hantzsch Ester as a Hydrogen Donor in Chiral Phosphoric Acid Catalyzed Asymmetric Reductive Amination of Ketones

Kyung Hee Kim, Takahiko Akiyama, Cheol-Hong Cheon

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Described herein are differences in behavior between a Hantzsch ester and a benzothiazoline as hydrogen donors in the chiral phosphoric acid catalyzed asymmetric reductive amination of ketones with p-anisidine. The asymmetric reductive amination of ketones with a Hantzsch ester as a hydrogen donor provided the corresponding chiral amines exclusively, regardless of the structures of the ketones, whereas a similar transformation with a benzothiazoline provided chiral amines and p-methoxyphenyl-protected primary amines in variable yields, depending on the structures of both the ketones and benzothiazolines. Because a benzothiazoline has an N,S-acetal moiety that is vulnerable to p-anisidine, the primary amine can be formed through transimination of the benzothiazoline with p-anisidine followed by reduction of the resulting aldimine with remaining benzothiazoline.

Original languageEnglish
Pages (from-to)274-279
Number of pages6
JournalChemistry - An Asian Journal
Volume11
Issue number2
DOIs
Publication statusPublished - 2016 Jan 20

Keywords

  • benzothiazolines
  • chiral phosphoric acid catalysis
  • enantioselective reductive amination
  • Hantzsch ester
  • organic hydrogen donor

ASJC Scopus subject areas

  • Chemistry(all)

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