Catalytic asymmetric hydrogenation of α-(acetamido)acrylates using TRAP trans-chelating chiral bisphosphine ligands

Remarkable effects of ligand P-substituent and hydrogen pressure on enantioselectivity

Ryoichi Kuwano, M. Sawamura, Y. Ito

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Abstract

The catalytic asymmetric hydrogenation of α-(acetamido)acrylates was carded out with the rhodium complexes prepared from [Rh(cod)2]BF4 and trans-chelating chiral bisphosphine ligands, (S,S)-2,2'-bis[(R)-1-(dialkylphosphino)ethyl]-1,1'-biferrocenes [(R,R)-(S,S)-TRAPs]. In the reaction of β-unsubstituted or β-monosubstituted α-(acetamido)acrylates [(E)-RCH=C(NHAc)CO2Me], the selectivity for (R)-hydrogenation product increased with decreasing steric demand of the substrate β-substituent and the ligand P-substituent as well as decreasing hydrogen pressure. The selectivity for the (R)-product in the reaction with EtTRAP-rhodium catalyst at 60 °C and 0.5 kg cm-2 of hydrogen pressure was as follows: R = H, 96% ee; R = Me, 92% ee; R = Ph, 77% ee; R = i-Pr, 57% ee. The remarkable steric and pressure effects caused a dramatic reversal of enantioselectivity in the reaction of methyl 2-(N-acetylamino)cinnamate (R = Ph). For example, the selectivity of 87% (R) with EtTRAP at 60 °C and 0.1 kg cm-2 of hydrogen pressure has reversed to 92% (S) with i-BuTRAP at 15 °C and atmospheric hydrogen pressure. Hydrogenation of the β,β-disubstituted α-(acetamido)acrylates proceeded smoothly at 15 °C and atmospheric hydrogen pressure with high enantioselectivity in favor of the 2S-isomers when EtTRAP or BuTRAP was employed as the chiral ligand.

Original languageEnglish
Pages (from-to)2571-2578
Number of pages8
JournalBulletin of the Chemical Society of Japan
Volume73
Issue number11
DOIs
Publication statusPublished - Nov 1 2000

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Acrylates
Enantioselectivity
Chelation
Hydrogenation
Hydrogen
Ligands
Rhodium
Cinnamates
Pressure effects
Isomers
Catalysts
Substrates

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

Cite this

@article{e9c8abb2eaf649f8a6f7755a27d0066d,
title = "Catalytic asymmetric hydrogenation of α-(acetamido)acrylates using TRAP trans-chelating chiral bisphosphine ligands: Remarkable effects of ligand P-substituent and hydrogen pressure on enantioselectivity",
abstract = "The catalytic asymmetric hydrogenation of α-(acetamido)acrylates was carded out with the rhodium complexes prepared from [Rh(cod)2]BF4 and trans-chelating chiral bisphosphine ligands, (S,S)-2,2'-bis[(R)-1-(dialkylphosphino)ethyl]-1,1'-biferrocenes [(R,R)-(S,S)-TRAPs]. In the reaction of β-unsubstituted or β-monosubstituted α-(acetamido)acrylates [(E)-RCH=C(NHAc)CO2Me], the selectivity for (R)-hydrogenation product increased with decreasing steric demand of the substrate β-substituent and the ligand P-substituent as well as decreasing hydrogen pressure. The selectivity for the (R)-product in the reaction with EtTRAP-rhodium catalyst at 60 °C and 0.5 kg cm-2 of hydrogen pressure was as follows: R = H, 96{\%} ee; R = Me, 92{\%} ee; R = Ph, 77{\%} ee; R = i-Pr, 57{\%} ee. The remarkable steric and pressure effects caused a dramatic reversal of enantioselectivity in the reaction of methyl 2-(N-acetylamino)cinnamate (R = Ph). For example, the selectivity of 87{\%} (R) with EtTRAP at 60 °C and 0.1 kg cm-2 of hydrogen pressure has reversed to 92{\%} (S) with i-BuTRAP at 15 °C and atmospheric hydrogen pressure. Hydrogenation of the β,β-disubstituted α-(acetamido)acrylates proceeded smoothly at 15 °C and atmospheric hydrogen pressure with high enantioselectivity in favor of the 2S-isomers when EtTRAP or BuTRAP was employed as the chiral ligand.",
author = "Ryoichi Kuwano and M. Sawamura and Y. Ito",
year = "2000",
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doi = "10.1246/bcsj.73.2571",
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TY - JOUR

T1 - Catalytic asymmetric hydrogenation of α-(acetamido)acrylates using TRAP trans-chelating chiral bisphosphine ligands

T2 - Remarkable effects of ligand P-substituent and hydrogen pressure on enantioselectivity

AU - Kuwano, Ryoichi

AU - Sawamura, M.

AU - Ito, Y.

PY - 2000/11/1

Y1 - 2000/11/1

N2 - The catalytic asymmetric hydrogenation of α-(acetamido)acrylates was carded out with the rhodium complexes prepared from [Rh(cod)2]BF4 and trans-chelating chiral bisphosphine ligands, (S,S)-2,2'-bis[(R)-1-(dialkylphosphino)ethyl]-1,1'-biferrocenes [(R,R)-(S,S)-TRAPs]. In the reaction of β-unsubstituted or β-monosubstituted α-(acetamido)acrylates [(E)-RCH=C(NHAc)CO2Me], the selectivity for (R)-hydrogenation product increased with decreasing steric demand of the substrate β-substituent and the ligand P-substituent as well as decreasing hydrogen pressure. The selectivity for the (R)-product in the reaction with EtTRAP-rhodium catalyst at 60 °C and 0.5 kg cm-2 of hydrogen pressure was as follows: R = H, 96% ee; R = Me, 92% ee; R = Ph, 77% ee; R = i-Pr, 57% ee. The remarkable steric and pressure effects caused a dramatic reversal of enantioselectivity in the reaction of methyl 2-(N-acetylamino)cinnamate (R = Ph). For example, the selectivity of 87% (R) with EtTRAP at 60 °C and 0.1 kg cm-2 of hydrogen pressure has reversed to 92% (S) with i-BuTRAP at 15 °C and atmospheric hydrogen pressure. Hydrogenation of the β,β-disubstituted α-(acetamido)acrylates proceeded smoothly at 15 °C and atmospheric hydrogen pressure with high enantioselectivity in favor of the 2S-isomers when EtTRAP or BuTRAP was employed as the chiral ligand.

AB - The catalytic asymmetric hydrogenation of α-(acetamido)acrylates was carded out with the rhodium complexes prepared from [Rh(cod)2]BF4 and trans-chelating chiral bisphosphine ligands, (S,S)-2,2'-bis[(R)-1-(dialkylphosphino)ethyl]-1,1'-biferrocenes [(R,R)-(S,S)-TRAPs]. In the reaction of β-unsubstituted or β-monosubstituted α-(acetamido)acrylates [(E)-RCH=C(NHAc)CO2Me], the selectivity for (R)-hydrogenation product increased with decreasing steric demand of the substrate β-substituent and the ligand P-substituent as well as decreasing hydrogen pressure. The selectivity for the (R)-product in the reaction with EtTRAP-rhodium catalyst at 60 °C and 0.5 kg cm-2 of hydrogen pressure was as follows: R = H, 96% ee; R = Me, 92% ee; R = Ph, 77% ee; R = i-Pr, 57% ee. The remarkable steric and pressure effects caused a dramatic reversal of enantioselectivity in the reaction of methyl 2-(N-acetylamino)cinnamate (R = Ph). For example, the selectivity of 87% (R) with EtTRAP at 60 °C and 0.1 kg cm-2 of hydrogen pressure has reversed to 92% (S) with i-BuTRAP at 15 °C and atmospheric hydrogen pressure. Hydrogenation of the β,β-disubstituted α-(acetamido)acrylates proceeded smoothly at 15 °C and atmospheric hydrogen pressure with high enantioselectivity in favor of the 2S-isomers when EtTRAP or BuTRAP was employed as the chiral ligand.

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U2 - 10.1246/bcsj.73.2571

DO - 10.1246/bcsj.73.2571

M3 - Article

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JO - Bulletin of the Chemical Society of Japan

JF - Bulletin of the Chemical Society of Japan

SN - 0009-2673

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