Asymmetric hydrogenation of 1,4,5,6-tetrahydropyrazine-2-(N-tert- butyl)carboxamide catalyzed by trans-chelating chiral diphosphine-rhodium complexes

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Abstract

Highly enantioselective hydrogenation of 1,4,5,6-tetrahydropyrazine-2- (N-tert-butyl)carboxamide (2) was accomplished by a rhodium complex coordinated with a chiral diphosphine TRAP ligand, which is possible to chelate to a transition metal atom in a trans-manner. Of particular interest is that (R,R)-(S,S)-i-BuTRAP gave 97% ee of the corresponding piperazine-2- carboxylic acid derivative (3) with (S) configuration, while the hydrogenation with (R,R)-(S,S)-MeTRAP-rhodium catalyst provided (R)-3 with up to 85% ee. 31P NMR studies of behavior of i-Bu- and MeTRAP-rhodium catalysts during the reaction suggest that the asymmetric hydrogenation of 2 with TRAPs may involve two competitive reaction pathways, giving their respective enantiomeric products 3.

Original languageEnglish
Pages (from-to)1232-1237
Number of pages6
JournalJournal of Organic Chemistry
Volume64
Issue number4
DOIs
Publication statusPublished - Feb 19 1999
Externally publishedYes

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Rhodium
Chelation
Hydrogenation
Catalysts
Transition metals
Nuclear magnetic resonance
Ligands
Derivatives
Atoms

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

Cite this

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title = "Asymmetric hydrogenation of 1,4,5,6-tetrahydropyrazine-2-(N-tert- butyl)carboxamide catalyzed by trans-chelating chiral diphosphine-rhodium complexes",
abstract = "Highly enantioselective hydrogenation of 1,4,5,6-tetrahydropyrazine-2- (N-tert-butyl)carboxamide (2) was accomplished by a rhodium complex coordinated with a chiral diphosphine TRAP ligand, which is possible to chelate to a transition metal atom in a trans-manner. Of particular interest is that (R,R)-(S,S)-i-BuTRAP gave 97{\%} ee of the corresponding piperazine-2- carboxylic acid derivative (3) with (S) configuration, while the hydrogenation with (R,R)-(S,S)-MeTRAP-rhodium catalyst provided (R)-3 with up to 85{\%} ee. 31P NMR studies of behavior of i-Bu- and MeTRAP-rhodium catalysts during the reaction suggest that the asymmetric hydrogenation of 2 with TRAPs may involve two competitive reaction pathways, giving their respective enantiomeric products 3.",
author = "Ryoichi Kuwano and Y. Ito",
year = "1999",
month = "2",
day = "19",
doi = "10.1021/jo981939u",
language = "English",
volume = "64",
pages = "1232--1237",
journal = "Journal of Organic Chemistry",
issn = "0022-3263",
publisher = "American Chemical Society",
number = "4",

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TY - JOUR

T1 - Asymmetric hydrogenation of 1,4,5,6-tetrahydropyrazine-2-(N-tert- butyl)carboxamide catalyzed by trans-chelating chiral diphosphine-rhodium complexes

AU - Kuwano, Ryoichi

AU - Ito, Y.

PY - 1999/2/19

Y1 - 1999/2/19

N2 - Highly enantioselective hydrogenation of 1,4,5,6-tetrahydropyrazine-2- (N-tert-butyl)carboxamide (2) was accomplished by a rhodium complex coordinated with a chiral diphosphine TRAP ligand, which is possible to chelate to a transition metal atom in a trans-manner. Of particular interest is that (R,R)-(S,S)-i-BuTRAP gave 97% ee of the corresponding piperazine-2- carboxylic acid derivative (3) with (S) configuration, while the hydrogenation with (R,R)-(S,S)-MeTRAP-rhodium catalyst provided (R)-3 with up to 85% ee. 31P NMR studies of behavior of i-Bu- and MeTRAP-rhodium catalysts during the reaction suggest that the asymmetric hydrogenation of 2 with TRAPs may involve two competitive reaction pathways, giving their respective enantiomeric products 3.

AB - Highly enantioselective hydrogenation of 1,4,5,6-tetrahydropyrazine-2- (N-tert-butyl)carboxamide (2) was accomplished by a rhodium complex coordinated with a chiral diphosphine TRAP ligand, which is possible to chelate to a transition metal atom in a trans-manner. Of particular interest is that (R,R)-(S,S)-i-BuTRAP gave 97% ee of the corresponding piperazine-2- carboxylic acid derivative (3) with (S) configuration, while the hydrogenation with (R,R)-(S,S)-MeTRAP-rhodium catalyst provided (R)-3 with up to 85% ee. 31P NMR studies of behavior of i-Bu- and MeTRAP-rhodium catalysts during the reaction suggest that the asymmetric hydrogenation of 2 with TRAPs may involve two competitive reaction pathways, giving their respective enantiomeric products 3.

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U2 - 10.1021/jo981939u

DO - 10.1021/jo981939u

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