Enantioselective hydroformylation of 2- and 4-substituted styrenes with PtCl2[(R)-BINAP] + SnCl2 ‘in situ’ catalyst

Péter Pongrácz, László Kollár

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Two sets of styrenes possessing various substituents either in ortho or para position were hydroformylated in the presence of ‘in situ’ catalyst formed from PtCl2[(R)-BINAP] and tin(II) chloride. The reversal of the absolute configuration of the preferred enantiomers was observed using both sets of substrates by the variation of the reaction temperature in the range of 40–100 °C. In case of the 4-substituted styrenes, the reversal temperature of the enantioselectivity shows correlation with the Hammett substituent constants, i.e., with the electron donor or electron acceptor properties of the para-substituents. This phenomenon was explained by the reversible formation of the Pt-branched alkyl intermediates, leading to the corresponding (R)- and (S)-enantiomers of 2-arylpropanals. Strong substituent effect on the regioselectivity was observed in the hydroformylation of 2-substituted styrenes: the presence of substituents characterised by larger steric parameter resulted in the highly favoured formation of the linear aldehyde. For instance, regioselectivities of 45%, 22% and 7% towards branched aldehyde were obtained with styrene, 2-fluoro- and 2-bromostyrene, respectively, at 80 °C reaction temperature. In addition to the characteristic change of regioselectivity, the reversal of absolute configuration as a function of reaction temperature was also observed.

Original languageEnglish
Pages (from-to)118-123
Number of pages6
JournalJournal of Organometallic Chemistry
Volume824
DOIs
Publication statusPublished - Dec 1 2016

Fingerprint

Styrenes
Hydroformylation
styrenes
Regioselectivity
Styrene
catalysts
Catalysts
Temperature
Enantiomers
enantiomers
Aldehydes
aldehydes
Electrons
temperature
Tin
Enantioselectivity
configurations
Chlorides
tin
electrons

Keywords

  • Enantioselectivity
  • Hydroformylation
  • Platinum
  • Substituent effect
  • Temperature effect

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

@article{ae837d4aecea48eb98a5a1e6dfa2f338,
title = "Enantioselective hydroformylation of 2- and 4-substituted styrenes with PtCl2[(R)-BINAP] + SnCl2 ‘in situ’ catalyst",
abstract = "Two sets of styrenes possessing various substituents either in ortho or para position were hydroformylated in the presence of ‘in situ’ catalyst formed from PtCl2[(R)-BINAP] and tin(II) chloride. The reversal of the absolute configuration of the preferred enantiomers was observed using both sets of substrates by the variation of the reaction temperature in the range of 40–100 °C. In case of the 4-substituted styrenes, the reversal temperature of the enantioselectivity shows correlation with the Hammett substituent constants, i.e., with the electron donor or electron acceptor properties of the para-substituents. This phenomenon was explained by the reversible formation of the Pt-branched alkyl intermediates, leading to the corresponding (R)- and (S)-enantiomers of 2-arylpropanals. Strong substituent effect on the regioselectivity was observed in the hydroformylation of 2-substituted styrenes: the presence of substituents characterised by larger steric parameter resulted in the highly favoured formation of the linear aldehyde. For instance, regioselectivities of 45{\%}, 22{\%} and 7{\%} towards branched aldehyde were obtained with styrene, 2-fluoro- and 2-bromostyrene, respectively, at 80 °C reaction temperature. In addition to the characteristic change of regioselectivity, the reversal of absolute configuration as a function of reaction temperature was also observed.",
keywords = "Enantioselectivity, Hydroformylation, Platinum, Substituent effect, Temperature effect",
author = "P{\'e}ter Pongr{\'a}cz and L{\'a}szl{\'o} Koll{\'a}r",
year = "2016",
month = "12",
day = "1",
doi = "10.1016/j.jorganchem.2016.10.013",
language = "English",
volume = "824",
pages = "118--123",
journal = "Journal of Organometallic Chemistry",
issn = "0022-328X",
publisher = "Elsevier",

}

TY - JOUR

T1 - Enantioselective hydroformylation of 2- and 4-substituted styrenes with PtCl2[(R)-BINAP] + SnCl2 ‘in situ’ catalyst

AU - Pongrácz, Péter

AU - Kollár, László

PY - 2016/12/1

Y1 - 2016/12/1

N2 - Two sets of styrenes possessing various substituents either in ortho or para position were hydroformylated in the presence of ‘in situ’ catalyst formed from PtCl2[(R)-BINAP] and tin(II) chloride. The reversal of the absolute configuration of the preferred enantiomers was observed using both sets of substrates by the variation of the reaction temperature in the range of 40–100 °C. In case of the 4-substituted styrenes, the reversal temperature of the enantioselectivity shows correlation with the Hammett substituent constants, i.e., with the electron donor or electron acceptor properties of the para-substituents. This phenomenon was explained by the reversible formation of the Pt-branched alkyl intermediates, leading to the corresponding (R)- and (S)-enantiomers of 2-arylpropanals. Strong substituent effect on the regioselectivity was observed in the hydroformylation of 2-substituted styrenes: the presence of substituents characterised by larger steric parameter resulted in the highly favoured formation of the linear aldehyde. For instance, regioselectivities of 45%, 22% and 7% towards branched aldehyde were obtained with styrene, 2-fluoro- and 2-bromostyrene, respectively, at 80 °C reaction temperature. In addition to the characteristic change of regioselectivity, the reversal of absolute configuration as a function of reaction temperature was also observed.

AB - Two sets of styrenes possessing various substituents either in ortho or para position were hydroformylated in the presence of ‘in situ’ catalyst formed from PtCl2[(R)-BINAP] and tin(II) chloride. The reversal of the absolute configuration of the preferred enantiomers was observed using both sets of substrates by the variation of the reaction temperature in the range of 40–100 °C. In case of the 4-substituted styrenes, the reversal temperature of the enantioselectivity shows correlation with the Hammett substituent constants, i.e., with the electron donor or electron acceptor properties of the para-substituents. This phenomenon was explained by the reversible formation of the Pt-branched alkyl intermediates, leading to the corresponding (R)- and (S)-enantiomers of 2-arylpropanals. Strong substituent effect on the regioselectivity was observed in the hydroformylation of 2-substituted styrenes: the presence of substituents characterised by larger steric parameter resulted in the highly favoured formation of the linear aldehyde. For instance, regioselectivities of 45%, 22% and 7% towards branched aldehyde were obtained with styrene, 2-fluoro- and 2-bromostyrene, respectively, at 80 °C reaction temperature. In addition to the characteristic change of regioselectivity, the reversal of absolute configuration as a function of reaction temperature was also observed.

KW - Enantioselectivity

KW - Hydroformylation

KW - Platinum

KW - Substituent effect

KW - Temperature effect

UR - http://www.scopus.com/inward/record.url?scp=84991661300&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84991661300&partnerID=8YFLogxK

U2 - 10.1016/j.jorganchem.2016.10.013

DO - 10.1016/j.jorganchem.2016.10.013

M3 - Article

VL - 824

SP - 118

EP - 123

JO - Journal of Organometallic Chemistry

JF - Journal of Organometallic Chemistry

SN - 0022-328X

ER -