Accessing stable magnesium acyl compounds: reductive cleavage of esters by magnesium(I) dimers

Aaron J. Boutland; Carlos A. Lamsfus; Brant Maitland; Laurent Maron; Andreas Stasch; Cameron Jones

doi:10.1002/chem.201703061

Accessing stable magnesium acyl compounds: reductive cleavage of esters by magnesium(I) dimers

Aaron J. Boutland, Carlos A. Lamsfus, Brant Maitland, Laurent Maron, Andreas Stasch, Cameron Jones

School of Chemistry

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

Abstract

The first examples of magnesium acyls, [(Nacnac)Mg{μ-C(Ph)O}(μ-OR)Mg(Nacnac)] (R = Me, But or Ph; Nacnac = [HC(MeCNAr)₂]^-; Ar = C₆H₂Me_3-2,4,6 (^MesNacnac), C₆H₃Et_2-2,6 (^DepNacnac), C₆H₃Pri_2-2,6 (^DipNacnac)), have been prepared by reductive cleavage of a series of esters using dimeric magnesium(I) reducing agents, [{(Nacnac)Mg}₂]. Crystallographic studies reveal the complexes to be dimeric, being bridged by both phenyl-acyl and alkoxide/aryloxide fragments. The crystal structures, combined with results of spectroscopic and computational studies suggest that the nature of the acyl ligands within these complexes should be viewed as lying somewhere between anionic umpolung acyl and oxo-carbene. However, reactions of the acyl complexes with a variety of organic electrophiles did not provide evidence of umpolung acyl reactivity. A number of attempts to prepare alkoxide free magnesium acyls were carried out, and while these were unsuccessful, they did lead to unusual products, the crystallographic and spectroscopic details of which are discussed.

Original language	English
Pages (from-to)	14049-14055
Journal	Chemistry - A European Journal
Volume	23
Issue number	56
Early online date	6 Sept 2017
DOIs	https://doi.org/10.1002/chem.201703061
Publication status	Published - 9 Oct 2017

Keywords

Magnesium acyl
Magnesium(I)
Ester cleavage
Reduction
Umpolung

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10.1002/chem.201703061

CEJ_Mg-acyl
© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. This work has been made available online in accordance with the publisher’s policies. This is the author created accepted version manuscript following peer review and as such may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1002/chem.201703061
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Cite this

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title = "Accessing stable magnesium acyl compounds: reductive cleavage of esters by magnesium(I) dimers",

abstract = "The first examples of magnesium acyls, [(Nacnac)Mg{μ-C(Ph)O}(μ-OR)Mg(Nacnac)] (R = Me, But or Ph; Nacnac = [HC(MeCNAr)2]-; Ar = C6H2Me3-2,4,6 (MesNacnac), C6H3Et2-2,6 (DepNacnac), C6H3Pri2-2,6 (DipNacnac)), have been prepared by reductive cleavage of a series of esters using dimeric magnesium(I) reducing agents, [{(Nacnac)Mg}2]. Crystallographic studies reveal the complexes to be dimeric, being bridged by both phenyl-acyl and alkoxide/aryloxide fragments. The crystal structures, combined with results of spectroscopic and computational studies suggest that the nature of the acyl ligands within these complexes should be viewed as lying somewhere between anionic umpolung acyl and oxo-carbene. However, reactions of the acyl complexes with a variety of organic electrophiles did not provide evidence of umpolung acyl reactivity. A number of attempts to prepare alkoxide free magnesium acyls were carried out, and while these were unsuccessful, they did lead to unusual products, the crystallographic and spectroscopic details of which are discussed.",

keywords = "Magnesium acyl, Magnesium(I), Ester cleavage, Reduction, Umpolung",

author = "Boutland, {Aaron J.} and Lamsfus, {Carlos A.} and Brant Maitland and Laurent Maron and Andreas Stasch and Cameron Jones",

note = "C.J. and A.S. thank the Australian Research Council for financial support. C.J. also thanks the U.S. Air Force Asian Office of Aerospace Research and Development (grant FA2386-14-1-4043). ",

year = "2017",

month = oct,

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doi = "10.1002/chem.201703061",

language = "English",

volume = "23",

pages = "14049--14055",

journal = "Chemistry - A European Journal",

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TY - JOUR

T1 - Accessing stable magnesium acyl compounds

T2 - reductive cleavage of esters by magnesium(I) dimers

AU - Boutland, Aaron J.

AU - Lamsfus, Carlos A.

AU - Maitland, Brant

AU - Maron, Laurent

AU - Stasch, Andreas

AU - Jones, Cameron

N1 - C.J. and A.S. thank the Australian Research Council for financial support. C.J. also thanks the U.S. Air Force Asian Office of Aerospace Research and Development (grant FA2386-14-1-4043).

PY - 2017/10/9

Y1 - 2017/10/9

N2 - The first examples of magnesium acyls, [(Nacnac)Mg{μ-C(Ph)O}(μ-OR)Mg(Nacnac)] (R = Me, But or Ph; Nacnac = [HC(MeCNAr)2]-; Ar = C6H2Me3-2,4,6 (MesNacnac), C6H3Et2-2,6 (DepNacnac), C6H3Pri2-2,6 (DipNacnac)), have been prepared by reductive cleavage of a series of esters using dimeric magnesium(I) reducing agents, [{(Nacnac)Mg}2]. Crystallographic studies reveal the complexes to be dimeric, being bridged by both phenyl-acyl and alkoxide/aryloxide fragments. The crystal structures, combined with results of spectroscopic and computational studies suggest that the nature of the acyl ligands within these complexes should be viewed as lying somewhere between anionic umpolung acyl and oxo-carbene. However, reactions of the acyl complexes with a variety of organic electrophiles did not provide evidence of umpolung acyl reactivity. A number of attempts to prepare alkoxide free magnesium acyls were carried out, and while these were unsuccessful, they did lead to unusual products, the crystallographic and spectroscopic details of which are discussed.

AB - The first examples of magnesium acyls, [(Nacnac)Mg{μ-C(Ph)O}(μ-OR)Mg(Nacnac)] (R = Me, But or Ph; Nacnac = [HC(MeCNAr)2]-; Ar = C6H2Me3-2,4,6 (MesNacnac), C6H3Et2-2,6 (DepNacnac), C6H3Pri2-2,6 (DipNacnac)), have been prepared by reductive cleavage of a series of esters using dimeric magnesium(I) reducing agents, [{(Nacnac)Mg}2]. Crystallographic studies reveal the complexes to be dimeric, being bridged by both phenyl-acyl and alkoxide/aryloxide fragments. The crystal structures, combined with results of spectroscopic and computational studies suggest that the nature of the acyl ligands within these complexes should be viewed as lying somewhere between anionic umpolung acyl and oxo-carbene. However, reactions of the acyl complexes with a variety of organic electrophiles did not provide evidence of umpolung acyl reactivity. A number of attempts to prepare alkoxide free magnesium acyls were carried out, and while these were unsuccessful, they did lead to unusual products, the crystallographic and spectroscopic details of which are discussed.

KW - Magnesium acyl

KW - Magnesium(I)

KW - Ester cleavage

KW - Reduction

KW - Umpolung

UR - http://onlinelibrary.wiley.com/doi/10.1002/chem.201703061/full#footer-support-info

U2 - 10.1002/chem.201703061

DO - 10.1002/chem.201703061

M3 - Article

SN - 0947-6539

VL - 23

SP - 14049

EP - 14055

JO - Chemistry - A European Journal

JF - Chemistry - A European Journal

IS - 56

ER -

Accessing stable magnesium acyl compounds: reductive cleavage of esters by magnesium(I) dimers

Abstract

Keywords

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