Ultrasonics in asymmetric syntheses. Sonochemical enantioselective hydrogenation of prochiral C=O groups over platinum catalysts

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Abstract

The sonochemical enantioselective hydrogenation of various prochiral carbonyl compounds to the corresponding (R)-hydroxy derivatives over different platinum catalysts using cinchonidine as chiral modifier is described. The carbonyl derivatives studied were trifluoromethyl ketones and α- and β-ketoesters. The sonochemical pretreatment of the catalyst-modifier system was found to be mostly advantageous in increasing the optical yield. Moreover, the ultrasonically promoted reactions provided the best enantiomeric excesses (ee%) ever obtained in this heterogeneous catalytic system (methyl pyruvate 95 ee%, ethyl 4-phenyl-2-oxobutyrate 95 ee%, and ethyl benzoylformate 92 ee%). In a few cases, however, the insonation did not result in enhancement in enantioselectivities. On the basis of the comparison with conventional reactions the limitations of the ultrasonic irradiation in asymmetric hydrogenations are also drawn.

Original languageEnglish
Pages (from-to)470-474
Number of pages5
JournalChirality
Volume11
Issue number5-6
DOIs
Publication statusPublished - 1999

Fingerprint

Hydrogenation
Platinum
Ultrasonics
Derivatives
Carbonyl compounds
Catalysts
Enantioselectivity
Ketones
Irradiation
alpha-ketobutyric acid
methyl pyruvate
cinchonidine
phenylglyoxylic acid

Keywords

  • Alpha-ketoesters
  • Asymmetric hydrogenation
  • Beta- ketoesters
  • Cinchonidine
  • Enantioselective
  • Methyl ketones
  • Pt-alumina catalyst
  • Ultrasound

ASJC Scopus subject areas

  • Analytical Chemistry
  • Drug Discovery
  • Organic Chemistry
  • Pharmacology

Cite this

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title = "Ultrasonics in asymmetric syntheses. Sonochemical enantioselective hydrogenation of prochiral C=O groups over platinum catalysts",
abstract = "The sonochemical enantioselective hydrogenation of various prochiral carbonyl compounds to the corresponding (R)-hydroxy derivatives over different platinum catalysts using cinchonidine as chiral modifier is described. The carbonyl derivatives studied were trifluoromethyl ketones and α- and β-ketoesters. The sonochemical pretreatment of the catalyst-modifier system was found to be mostly advantageous in increasing the optical yield. Moreover, the ultrasonically promoted reactions provided the best enantiomeric excesses (ee{\%}) ever obtained in this heterogeneous catalytic system (methyl pyruvate 95 ee{\%}, ethyl 4-phenyl-2-oxobutyrate 95 ee{\%}, and ethyl benzoylformate 92 ee{\%}). In a few cases, however, the insonation did not result in enhancement in enantioselectivities. On the basis of the comparison with conventional reactions the limitations of the ultrasonic irradiation in asymmetric hydrogenations are also drawn.",
keywords = "Alpha-ketoesters, Asymmetric hydrogenation, Beta- ketoesters, Cinchonidine, Enantioselective, Methyl ketones, Pt-alumina catalyst, Ultrasound",
author = "B{\'e}la T{\"o}r{\"o}k and K. Bal{\'a}zsik and G. Sz{\"o}llősi and K. Felf{\"o}ldi and M. Bart{\'o}k",
year = "1999",
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T1 - Ultrasonics in asymmetric syntheses. Sonochemical enantioselective hydrogenation of prochiral C=O groups over platinum catalysts

AU - Török, Béla

AU - Balázsik, K.

AU - Szöllősi, G.

AU - Felföldi, K.

AU - Bartók, M.

PY - 1999

Y1 - 1999

N2 - The sonochemical enantioselective hydrogenation of various prochiral carbonyl compounds to the corresponding (R)-hydroxy derivatives over different platinum catalysts using cinchonidine as chiral modifier is described. The carbonyl derivatives studied were trifluoromethyl ketones and α- and β-ketoesters. The sonochemical pretreatment of the catalyst-modifier system was found to be mostly advantageous in increasing the optical yield. Moreover, the ultrasonically promoted reactions provided the best enantiomeric excesses (ee%) ever obtained in this heterogeneous catalytic system (methyl pyruvate 95 ee%, ethyl 4-phenyl-2-oxobutyrate 95 ee%, and ethyl benzoylformate 92 ee%). In a few cases, however, the insonation did not result in enhancement in enantioselectivities. On the basis of the comparison with conventional reactions the limitations of the ultrasonic irradiation in asymmetric hydrogenations are also drawn.

AB - The sonochemical enantioselective hydrogenation of various prochiral carbonyl compounds to the corresponding (R)-hydroxy derivatives over different platinum catalysts using cinchonidine as chiral modifier is described. The carbonyl derivatives studied were trifluoromethyl ketones and α- and β-ketoesters. The sonochemical pretreatment of the catalyst-modifier system was found to be mostly advantageous in increasing the optical yield. Moreover, the ultrasonically promoted reactions provided the best enantiomeric excesses (ee%) ever obtained in this heterogeneous catalytic system (methyl pyruvate 95 ee%, ethyl 4-phenyl-2-oxobutyrate 95 ee%, and ethyl benzoylformate 92 ee%). In a few cases, however, the insonation did not result in enhancement in enantioselectivities. On the basis of the comparison with conventional reactions the limitations of the ultrasonic irradiation in asymmetric hydrogenations are also drawn.

KW - Alpha-ketoesters

KW - Asymmetric hydrogenation

KW - Beta- ketoesters

KW - Cinchonidine

KW - Enantioselective

KW - Methyl ketones

KW - Pt-alumina catalyst

KW - Ultrasound

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M3 - Article

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