New data on the effect of steric constraints on the chiral induction in the Orito reaction

Hydrogenation of activated steroid ketones

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2 Citations (Scopus)

Abstract

Hydrogenation of α-ketoesters containing steroid groups at the ester side and at the keto carbonyl function of substrates was investigated the first time on Pt-alumina-cinchona alkaloids chiral catalysts using mild experimental conditions (room temperature, 1 bar hydrogen pressure, modifier concentration 1 mM) in the presence of acetic acid. Catalysts modified by cinchona alkaloids ensured enantioselective hydrogenation with 10-70% ee, depending on the steric structure of the substrate. In the absence of cinchonas racemic hydrogenation takes place, i.e. the chiral centers of the substrates do not participate in chiral induction. Experimental data so far obtained support the assumption that under stereochemical conditions not inhibiting adsorption of the substrate and after optimization of the experimental conditions, the Orito reaction may be rendered suitable for the asymmetric hydrogenation of bulky activated ketones. These results also supply additional evidence for the determinant role of the H-bonded adsorbed intermediate, the 1:1 complex of cinchona alkaloid and substrate in chiral induction under protic conditions.

Original languageEnglish
Pages (from-to)14-19
Number of pages6
JournalJournal of Molecular Catalysis A: Chemical
Volume294
Issue number1-2
DOIs
Publication statusPublished - Oct 15 2008

Fingerprint

steroids
Ketones
ketones
Cinchona Alkaloids
Hydrogenation
hydrogenation
induction
Steroids
alkaloids
Substrates
catalysts
Catalysts
Aluminum Oxide
acetic acid
Acetic acid
determinants
Acetic Acid
esters
Hydrogen
Esters

Keywords

  • Cinchona alkaloids
  • Diastereoselective hydrogenation
  • Platinum-alumina
  • Steric constraints
  • Steroids
  • VDC spectroscopy

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry
  • Process Chemistry and Technology

Cite this

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title = "New data on the effect of steric constraints on the chiral induction in the Orito reaction: Hydrogenation of activated steroid ketones",
abstract = "Hydrogenation of α-ketoesters containing steroid groups at the ester side and at the keto carbonyl function of substrates was investigated the first time on Pt-alumina-cinchona alkaloids chiral catalysts using mild experimental conditions (room temperature, 1 bar hydrogen pressure, modifier concentration 1 mM) in the presence of acetic acid. Catalysts modified by cinchona alkaloids ensured enantioselective hydrogenation with 10-70{\%} ee, depending on the steric structure of the substrate. In the absence of cinchonas racemic hydrogenation takes place, i.e. the chiral centers of the substrates do not participate in chiral induction. Experimental data so far obtained support the assumption that under stereochemical conditions not inhibiting adsorption of the substrate and after optimization of the experimental conditions, the Orito reaction may be rendered suitable for the asymmetric hydrogenation of bulky activated ketones. These results also supply additional evidence for the determinant role of the H-bonded adsorbed intermediate, the 1:1 complex of cinchona alkaloid and substrate in chiral induction under protic conditions.",
keywords = "Cinchona alkaloids, Diastereoselective hydrogenation, Platinum-alumina, Steric constraints, Steroids, VDC spectroscopy",
author = "K. Sz{\"o}ri and K. Bal{\'a}zsik and K. Felf{\"o}ldi and I. Bucsi and S. Cser{\'e}nyi and G. Sz{\"o}llősi and E. Vass and M. Holl{\'o}si and M. Bart{\'o}k",
year = "2008",
month = "10",
day = "15",
doi = "10.1016/j.molcata.2008.07.002",
language = "English",
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journal = "Journal of Molecular Catalysis A: Chemical",
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TY - JOUR

T1 - New data on the effect of steric constraints on the chiral induction in the Orito reaction

T2 - Hydrogenation of activated steroid ketones

AU - Szöri, K.

AU - Balázsik, K.

AU - Felföldi, K.

AU - Bucsi, I.

AU - Cserényi, S.

AU - Szöllősi, G.

AU - Vass, E.

AU - Hollósi, M.

AU - Bartók, M.

PY - 2008/10/15

Y1 - 2008/10/15

N2 - Hydrogenation of α-ketoesters containing steroid groups at the ester side and at the keto carbonyl function of substrates was investigated the first time on Pt-alumina-cinchona alkaloids chiral catalysts using mild experimental conditions (room temperature, 1 bar hydrogen pressure, modifier concentration 1 mM) in the presence of acetic acid. Catalysts modified by cinchona alkaloids ensured enantioselective hydrogenation with 10-70% ee, depending on the steric structure of the substrate. In the absence of cinchonas racemic hydrogenation takes place, i.e. the chiral centers of the substrates do not participate in chiral induction. Experimental data so far obtained support the assumption that under stereochemical conditions not inhibiting adsorption of the substrate and after optimization of the experimental conditions, the Orito reaction may be rendered suitable for the asymmetric hydrogenation of bulky activated ketones. These results also supply additional evidence for the determinant role of the H-bonded adsorbed intermediate, the 1:1 complex of cinchona alkaloid and substrate in chiral induction under protic conditions.

AB - Hydrogenation of α-ketoesters containing steroid groups at the ester side and at the keto carbonyl function of substrates was investigated the first time on Pt-alumina-cinchona alkaloids chiral catalysts using mild experimental conditions (room temperature, 1 bar hydrogen pressure, modifier concentration 1 mM) in the presence of acetic acid. Catalysts modified by cinchona alkaloids ensured enantioselective hydrogenation with 10-70% ee, depending on the steric structure of the substrate. In the absence of cinchonas racemic hydrogenation takes place, i.e. the chiral centers of the substrates do not participate in chiral induction. Experimental data so far obtained support the assumption that under stereochemical conditions not inhibiting adsorption of the substrate and after optimization of the experimental conditions, the Orito reaction may be rendered suitable for the asymmetric hydrogenation of bulky activated ketones. These results also supply additional evidence for the determinant role of the H-bonded adsorbed intermediate, the 1:1 complex of cinchona alkaloid and substrate in chiral induction under protic conditions.

KW - Cinchona alkaloids

KW - Diastereoselective hydrogenation

KW - Platinum-alumina

KW - Steric constraints

KW - Steroids

KW - VDC spectroscopy

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