Trimerisation of the cationic fragments [(η-ring)M(Aa)]+ ((η-ring) M = (η5-C5Me5)Rh, (η5-C5Me5)Ir,(η6-p-MeC 6H4iPr)Ru; Aa = α-amino acidate) with chiral self-recognition

Synthesis, characterisation, solution studies and catalytic reactions of the trimers

Daniel Carmona, Fernando J. Lahoz, Reinaldo Atencio, Luis A. Oro, M. Pilar Lamata, Fernando Viguri, Emilio San Jose, Cristina Vega, Josefa Reyes, Ferenc Joó, A. Kathó

Research output: Contribution to journalArticle

100 Citations (Scopus)

Abstract

The mononuclear neutral chlorides [(η-ring)M(Aa)Cl] ((η-ring)-M = (η5-C5Me5)Rh, (η5-C5Me5)Ir, (η6-p-MeC6H4i(Pr)Ru; Aa = α-amino acidate) were treated with AgBF4 to yield the corresponding new chiral trimers [{(η-ring)M(Aa)}3](BF4)3. Compounds [{(η5-C5Me5)Ir(Ala)}3](BF 4)3 (1b) and [{(η6-p-MeC6H4iPr)Ru(L-Pro)} 3](BF4)3 (6c) were characterised by X-ray diffraction. Trimerisation takes place by chiral self-recognition: the trimers RMRMRM (ρ isomer) or SMSMSM (o isomer), which have equal configuration at the metal centre, were the only diastereomers detected. In solution, a diastereomerisation process between both isomers occurs, where the equilibrium constant depends on the solvent, amino acidate, and metal. The different localisation of the polar groups (NH or NH2 moieties) on the molecular surface of the two diastereomers (ρ and σ) provides a qualitative explanation for the different diastereomer stability observed in solution. The new chiral trimers catalyse the reduction of unsaturated aldehydes to unsaturated alcohols by hydrogen transfer from aqueous sodium formate and the reduction of acetophenone by hydrogen transfer from 2-propanol with up to 75 % ee.

Original languageEnglish
Pages (from-to)1544-1564
Number of pages21
JournalChemistry - A European Journal
Volume5
Issue number5
Publication statusPublished - 1999

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Isomers
formic acid
Hydrogen
Metals
2-Propanol
Equilibrium constants
Propanol
Aldehydes
Chlorides
Alcohols
Sodium
X ray diffraction
acetophenone

Keywords

  • Amino acids
  • Asymmetric catalysis
  • Iridium
  • Rhodium
  • Ruthenium

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Trimerisation of the cationic fragments [(η-ring)M(Aa)]+ ((η-ring) M = (η5-C5Me5)Rh, (η5-C5Me5)Ir,(η6-p-MeC 6H4iPr)Ru; Aa = α-amino acidate) with chiral self-recognition : Synthesis, characterisation, solution studies and catalytic reactions of the trimers. / Carmona, Daniel; Lahoz, Fernando J.; Atencio, Reinaldo; Oro, Luis A.; Lamata, M. Pilar; Viguri, Fernando; San Jose, Emilio; Vega, Cristina; Reyes, Josefa; Joó, Ferenc; Kathó, A.

In: Chemistry - A European Journal, Vol. 5, No. 5, 1999, p. 1544-1564.

Research output: Contribution to journalArticle

Carmona, Daniel ; Lahoz, Fernando J. ; Atencio, Reinaldo ; Oro, Luis A. ; Lamata, M. Pilar ; Viguri, Fernando ; San Jose, Emilio ; Vega, Cristina ; Reyes, Josefa ; Joó, Ferenc ; Kathó, A. / Trimerisation of the cationic fragments [(η-ring)M(Aa)]+ ((η-ring) M = (η5-C5Me5)Rh, (η5-C5Me5)Ir,(η6-p-MeC 6H4iPr)Ru; Aa = α-amino acidate) with chiral self-recognition : Synthesis, characterisation, solution studies and catalytic reactions of the trimers. In: Chemistry - A European Journal. 1999 ; Vol. 5, No. 5. pp. 1544-1564.
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abstract = "The mononuclear neutral chlorides [(η-ring)M(Aa)Cl] ((η-ring)-M = (η5-C5Me5)Rh, (η5-C5Me5)Ir, (η6-p-MeC6H4i(Pr)Ru; Aa = α-amino acidate) were treated with AgBF4 to yield the corresponding new chiral trimers [{(η-ring)M(Aa)}3](BF4)3. Compounds [{(η5-C5Me5)Ir(Ala)}3](BF 4)3 (1b) and [{(η6-p-MeC6H4iPr)Ru(L-Pro)} 3](BF4)3 (6c) were characterised by X-ray diffraction. Trimerisation takes place by chiral self-recognition: the trimers RMRMRM (ρ isomer) or SMSMSM (o isomer), which have equal configuration at the metal centre, were the only diastereomers detected. In solution, a diastereomerisation process between both isomers occurs, where the equilibrium constant depends on the solvent, amino acidate, and metal. The different localisation of the polar groups (NH or NH2 moieties) on the molecular surface of the two diastereomers (ρ and σ) provides a qualitative explanation for the different diastereomer stability observed in solution. The new chiral trimers catalyse the reduction of unsaturated aldehydes to unsaturated alcohols by hydrogen transfer from aqueous sodium formate and the reduction of acetophenone by hydrogen transfer from 2-propanol with up to 75 {\%} ee.",
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T1 - Trimerisation of the cationic fragments [(η-ring)M(Aa)]+ ((η-ring) M = (η5-C5Me5)Rh, (η5-C5Me5)Ir,(η6-p-MeC 6H4iPr)Ru; Aa = α-amino acidate) with chiral self-recognition

T2 - Synthesis, characterisation, solution studies and catalytic reactions of the trimers

AU - Carmona, Daniel

AU - Lahoz, Fernando J.

AU - Atencio, Reinaldo

AU - Oro, Luis A.

AU - Lamata, M. Pilar

AU - Viguri, Fernando

AU - San Jose, Emilio

AU - Vega, Cristina

AU - Reyes, Josefa

AU - Joó, Ferenc

AU - Kathó, A.

PY - 1999

Y1 - 1999

N2 - The mononuclear neutral chlorides [(η-ring)M(Aa)Cl] ((η-ring)-M = (η5-C5Me5)Rh, (η5-C5Me5)Ir, (η6-p-MeC6H4i(Pr)Ru; Aa = α-amino acidate) were treated with AgBF4 to yield the corresponding new chiral trimers [{(η-ring)M(Aa)}3](BF4)3. Compounds [{(η5-C5Me5)Ir(Ala)}3](BF 4)3 (1b) and [{(η6-p-MeC6H4iPr)Ru(L-Pro)} 3](BF4)3 (6c) were characterised by X-ray diffraction. Trimerisation takes place by chiral self-recognition: the trimers RMRMRM (ρ isomer) or SMSMSM (o isomer), which have equal configuration at the metal centre, were the only diastereomers detected. In solution, a diastereomerisation process between both isomers occurs, where the equilibrium constant depends on the solvent, amino acidate, and metal. The different localisation of the polar groups (NH or NH2 moieties) on the molecular surface of the two diastereomers (ρ and σ) provides a qualitative explanation for the different diastereomer stability observed in solution. The new chiral trimers catalyse the reduction of unsaturated aldehydes to unsaturated alcohols by hydrogen transfer from aqueous sodium formate and the reduction of acetophenone by hydrogen transfer from 2-propanol with up to 75 % ee.

AB - The mononuclear neutral chlorides [(η-ring)M(Aa)Cl] ((η-ring)-M = (η5-C5Me5)Rh, (η5-C5Me5)Ir, (η6-p-MeC6H4i(Pr)Ru; Aa = α-amino acidate) were treated with AgBF4 to yield the corresponding new chiral trimers [{(η-ring)M(Aa)}3](BF4)3. Compounds [{(η5-C5Me5)Ir(Ala)}3](BF 4)3 (1b) and [{(η6-p-MeC6H4iPr)Ru(L-Pro)} 3](BF4)3 (6c) were characterised by X-ray diffraction. Trimerisation takes place by chiral self-recognition: the trimers RMRMRM (ρ isomer) or SMSMSM (o isomer), which have equal configuration at the metal centre, were the only diastereomers detected. In solution, a diastereomerisation process between both isomers occurs, where the equilibrium constant depends on the solvent, amino acidate, and metal. The different localisation of the polar groups (NH or NH2 moieties) on the molecular surface of the two diastereomers (ρ and σ) provides a qualitative explanation for the different diastereomer stability observed in solution. The new chiral trimers catalyse the reduction of unsaturated aldehydes to unsaturated alcohols by hydrogen transfer from aqueous sodium formate and the reduction of acetophenone by hydrogen transfer from 2-propanol with up to 75 % ee.

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KW - Asymmetric catalysis

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KW - Ruthenium

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