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

4 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

Fingerprint

Amination
Ketones
Hydrogen
Esters
Amines
Acetals
phosphoric acid
benzothiazoline
4-anisidine

Keywords

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

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

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title = "Remarkable Differences in Reactivity between Benzothiazoline and Hantzsch Ester as a Hydrogen Donor in Chiral Phosphoric Acid Catalyzed Asymmetric Reductive Amination of Ketones",
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.",
keywords = "benzothiazolines, chiral phosphoric acid catalysis, enantioselective reductive amination, Hantzsch ester, organic hydrogen donor",
author = "Kim, {Kyung Hee} and Takahiko Akiyama and Cheol-Hong Cheon",
year = "2016",
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TY - JOUR

T1 - Remarkable Differences in Reactivity between Benzothiazoline and Hantzsch Ester as a Hydrogen Donor in Chiral Phosphoric Acid Catalyzed Asymmetric Reductive Amination of Ketones

AU - Kim, Kyung Hee

AU - Akiyama, Takahiko

AU - Cheon, Cheol-Hong

PY - 2016/1/20

Y1 - 2016/1/20

N2 - 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.

AB - 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.

KW - benzothiazolines

KW - chiral phosphoric acid catalysis

KW - enantioselective reductive amination

KW - Hantzsch ester

KW - organic hydrogen donor

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U2 - 10.1002/asia.201501020

DO - 10.1002/asia.201501020

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JO - Chemistry - An Asian Journal

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