Remote steric effects of C2-symmetric planar-chiral terpyridine ligands on copper-catalyzed asymmetric cyclopropanation reactions

Nanako Mugishima; Nobuhiro Kanomata; Norihiko Akutsu; Hironobu Kubota

doi:10.1016/j.tetlet.2015.02.103

Remote steric effects of C₂-symmetric planar-chiral terpyridine ligands on copper-catalyzed asymmetric cyclopropanation reactions

Nanako Mugishima, Nobuhiro Kanomata, Norihiko Akutsu, Hironobu Kubota

School of Advanced Science and Engineering

Research output: Contribution to journal › Article › peer-review

6 Citations (Scopus)

Abstract

A series of enantioselective cyclopropanation reactions of substituted alkenes with diazoacetates was investigated in the presence of Cu(OTf)₂ with C₂-symmetric planar-chiral bridged 2,2′:6′,2″-terpyridines. Planar-chiral terpyridine-copper complexes exhibited moderate diastereomeric excesses with good enantioselectivities of cis-cyclopropane products in catalytic asymmetric cyclopropanation reactions of various styrene derivatives with ethyl diazoacetate. A remote steric effect was found to enhance enantioselectivity for the cyclopropanation induced by a sterically demanding substituent beyond the ansa-bridge of pyridinophane ligands on the other side of the reaction site as a relay of steric influences through flexible cyclophane bridges.

Original language	English
Pages (from-to)	1898-1903
Number of pages	6
Journal	Tetrahedron Letters
Volume	56
Issue number	14
DOIs	https://doi.org/10.1016/j.tetlet.2015.02.103
Publication status	Published - 2015 Apr 1

Keywords

Asymmetric cyclopropanation
Copper carbenoid
Planar chirality
Remote steric effect
Terpyridine

ASJC Scopus subject areas

Biochemistry
Drug Discovery
Organic Chemistry

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title = "Remote steric effects of C2-symmetric planar-chiral terpyridine ligands on copper-catalyzed asymmetric cyclopropanation reactions",

abstract = "A series of enantioselective cyclopropanation reactions of substituted alkenes with diazoacetates was investigated in the presence of Cu(OTf)2 with C2-symmetric planar-chiral bridged 2,2′:6′,2″-terpyridines. Planar-chiral terpyridine-copper complexes exhibited moderate diastereomeric excesses with good enantioselectivities of cis-cyclopropane products in catalytic asymmetric cyclopropanation reactions of various styrene derivatives with ethyl diazoacetate. A remote steric effect was found to enhance enantioselectivity for the cyclopropanation induced by a sterically demanding substituent beyond the ansa-bridge of pyridinophane ligands on the other side of the reaction site as a relay of steric influences through flexible cyclophane bridges.",

keywords = "Asymmetric cyclopropanation, Copper carbenoid, Planar chirality, Remote steric effect, Terpyridine",

author = "Nanako Mugishima and Nobuhiro Kanomata and Norihiko Akutsu and Hironobu Kubota",

note = "Funding Information: The authors acknowledge financial support through a Waseda University Grant for Special Research Projects 2011B-180 . ",

year = "2015",

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T1 - Remote steric effects of C2-symmetric planar-chiral terpyridine ligands on copper-catalyzed asymmetric cyclopropanation reactions

AU - Mugishima, Nanako

AU - Kanomata, Nobuhiro

AU - Akutsu, Norihiko

AU - Kubota, Hironobu

N1 - Funding Information: The authors acknowledge financial support through a Waseda University Grant for Special Research Projects 2011B-180 .

PY - 2015/4/1

Y1 - 2015/4/1

N2 - A series of enantioselective cyclopropanation reactions of substituted alkenes with diazoacetates was investigated in the presence of Cu(OTf)2 with C2-symmetric planar-chiral bridged 2,2′:6′,2″-terpyridines. Planar-chiral terpyridine-copper complexes exhibited moderate diastereomeric excesses with good enantioselectivities of cis-cyclopropane products in catalytic asymmetric cyclopropanation reactions of various styrene derivatives with ethyl diazoacetate. A remote steric effect was found to enhance enantioselectivity for the cyclopropanation induced by a sterically demanding substituent beyond the ansa-bridge of pyridinophane ligands on the other side of the reaction site as a relay of steric influences through flexible cyclophane bridges.

AB - A series of enantioselective cyclopropanation reactions of substituted alkenes with diazoacetates was investigated in the presence of Cu(OTf)2 with C2-symmetric planar-chiral bridged 2,2′:6′,2″-terpyridines. Planar-chiral terpyridine-copper complexes exhibited moderate diastereomeric excesses with good enantioselectivities of cis-cyclopropane products in catalytic asymmetric cyclopropanation reactions of various styrene derivatives with ethyl diazoacetate. A remote steric effect was found to enhance enantioselectivity for the cyclopropanation induced by a sterically demanding substituent beyond the ansa-bridge of pyridinophane ligands on the other side of the reaction site as a relay of steric influences through flexible cyclophane bridges.

KW - Asymmetric cyclopropanation

KW - Copper carbenoid

KW - Planar chirality

KW - Remote steric effect

KW - Terpyridine

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JF - Tetrahedron Letters

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