Highly enantioselective cyclopropanation of styrenes and diazoacetates catalyzed by 3-oxobutylideneaminatocobalt(II) complexes, part 2. Semiempirical analysis of diastereo and enantioselectivities

Taketo Ikeno, Izumi Iwakura, Tohru Yamada

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Abstract

A semiempirical analysis using the PM3(tm) method was performed on the 3-oxobutylideneaminatocobalt(II) complexes-catalyzed cyclopropanation. Although the energy diagram calculated by the PM3(tm) method had a contradiction, where the product was less stable than the reactant, the structures and the energies of the reactant and the transition state obtained by the PM3(tm) method could be relatively reliable by comparing with the results based on the density functional theory. Analysis of the transition states by the PM3(tm) method indicated that the olefin approached parallel to the cobalt-carbene bond with bisecting an O1-Co-O2 angle. It was revealed that the transition state affording the (1S,2S)-arylcyclopropanecarboxylic acid ester corresponding to the (1S,2S)-cobalt complex was the most stable, because of the lowest steric repulsion among the aryl group of the diamine unit, the ester moiety, and the approaching olefin. It was clarified that the enantioselectivity occurred due to the repulsion between the aryl group of the diamine unit and the ester moiety and that the diastereoselectivity was controlled by the repulsion between the ester moiety and the approaching olefin.

Original languageEnglish
Pages (from-to)2151-2160
Number of pages10
JournalBulletin of the Chemical Society of Japan
Volume74
Issue number11
DOIs
Publication statusPublished - 2001
Externally publishedYes

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Styrenes
Enantioselectivity
Esters
Alkenes
Diamines
Cobalt
Density functional theory
Acids

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

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title = "Highly enantioselective cyclopropanation of styrenes and diazoacetates catalyzed by 3-oxobutylideneaminatocobalt(II) complexes, part 2. Semiempirical analysis of diastereo and enantioselectivities",
abstract = "A semiempirical analysis using the PM3(tm) method was performed on the 3-oxobutylideneaminatocobalt(II) complexes-catalyzed cyclopropanation. Although the energy diagram calculated by the PM3(tm) method had a contradiction, where the product was less stable than the reactant, the structures and the energies of the reactant and the transition state obtained by the PM3(tm) method could be relatively reliable by comparing with the results based on the density functional theory. Analysis of the transition states by the PM3(tm) method indicated that the olefin approached parallel to the cobalt-carbene bond with bisecting an O1-Co-O2 angle. It was revealed that the transition state affording the (1S,2S)-arylcyclopropanecarboxylic acid ester corresponding to the (1S,2S)-cobalt complex was the most stable, because of the lowest steric repulsion among the aryl group of the diamine unit, the ester moiety, and the approaching olefin. It was clarified that the enantioselectivity occurred due to the repulsion between the aryl group of the diamine unit and the ester moiety and that the diastereoselectivity was controlled by the repulsion between the ester moiety and the approaching olefin.",
author = "Taketo Ikeno and Izumi Iwakura and Tohru Yamada",
year = "2001",
doi = "10.1246/bcsj.74.2151",
language = "English",
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TY - JOUR

T1 - Highly enantioselective cyclopropanation of styrenes and diazoacetates catalyzed by 3-oxobutylideneaminatocobalt(II) complexes, part 2. Semiempirical analysis of diastereo and enantioselectivities

AU - Ikeno, Taketo

AU - Iwakura, Izumi

AU - Yamada, Tohru

PY - 2001

Y1 - 2001

N2 - A semiempirical analysis using the PM3(tm) method was performed on the 3-oxobutylideneaminatocobalt(II) complexes-catalyzed cyclopropanation. Although the energy diagram calculated by the PM3(tm) method had a contradiction, where the product was less stable than the reactant, the structures and the energies of the reactant and the transition state obtained by the PM3(tm) method could be relatively reliable by comparing with the results based on the density functional theory. Analysis of the transition states by the PM3(tm) method indicated that the olefin approached parallel to the cobalt-carbene bond with bisecting an O1-Co-O2 angle. It was revealed that the transition state affording the (1S,2S)-arylcyclopropanecarboxylic acid ester corresponding to the (1S,2S)-cobalt complex was the most stable, because of the lowest steric repulsion among the aryl group of the diamine unit, the ester moiety, and the approaching olefin. It was clarified that the enantioselectivity occurred due to the repulsion between the aryl group of the diamine unit and the ester moiety and that the diastereoselectivity was controlled by the repulsion between the ester moiety and the approaching olefin.

AB - A semiempirical analysis using the PM3(tm) method was performed on the 3-oxobutylideneaminatocobalt(II) complexes-catalyzed cyclopropanation. Although the energy diagram calculated by the PM3(tm) method had a contradiction, where the product was less stable than the reactant, the structures and the energies of the reactant and the transition state obtained by the PM3(tm) method could be relatively reliable by comparing with the results based on the density functional theory. Analysis of the transition states by the PM3(tm) method indicated that the olefin approached parallel to the cobalt-carbene bond with bisecting an O1-Co-O2 angle. It was revealed that the transition state affording the (1S,2S)-arylcyclopropanecarboxylic acid ester corresponding to the (1S,2S)-cobalt complex was the most stable, because of the lowest steric repulsion among the aryl group of the diamine unit, the ester moiety, and the approaching olefin. It was clarified that the enantioselectivity occurred due to the repulsion between the aryl group of the diamine unit and the ester moiety and that the diastereoselectivity was controlled by the repulsion between the ester moiety and the approaching olefin.

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