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Unsymmetrical Saturated Ketones Resulting from Activations of Hydrocarbon C(sp3)–H and C(sp2)–H Bonds Effected by Cp*W(NO)(H)(η3-allyl) Complexes

R. Baillie, G. Lefèvre, R. Wakeham, A. Holmes, P. Legzdins, Russell Wakeham Orcid Logo

Organometallics, Volume: 34, Issue: 16, Pages: 4085 - 4092

Swansea University Author: Russell Wakeham Orcid Logo

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Abstract

C–H activations of a C(sp2)–H bond in benzene or a C(sp3)–H bond in mesitylene at 80 °C under CO pressure in undried solvents without rigorous exclusion of air and moisture can be effected with the 18e complexes Cp*W(NO)(H)(η3-CH2CHCMe2) (1), Cp*W(NO)(H)(η3-CH2CHCHMe) (2), and Cp*W(NO)(H)(η3-CH2CHCH...

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Published in: Organometallics
ISSN: 0276-7333 1520-6041
Published: American Chemical Society (ACS) 2015
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URI: https://cronfa.swan.ac.uk/Record/cronfa32708
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spelling 2017-03-28T10:56:08.0704768 v2 32708 2017-03-27 Unsymmetrical Saturated Ketones Resulting from Activations of Hydrocarbon C(sp3)–H and C(sp2)–H Bonds Effected by Cp*W(NO)(H)(η3-allyl) Complexes 28c45bbeeba294da7042950705b98e0a 0000-0002-4304-0243 Russell Wakeham Russell Wakeham true false 2017-03-27 EEN C–H activations of a C(sp2)–H bond in benzene or a C(sp3)–H bond in mesitylene at 80 °C under CO pressure in undried solvents without rigorous exclusion of air and moisture can be effected with the 18e complexes Cp*W(NO)(H)(η3-CH2CHCMe2) (1), Cp*W(NO)(H)(η3-CH2CHCHMe) (2), and Cp*W(NO)(H)(η3-CH2CHCHPh) (3) (Cp* = η5-C5Me5). These activations are regiospecific and afford in the case of complex 1 good yields of the unsymmetrical saturated ketones 4-methyl-1-phenylpentan-1-one (5) and 1-(3,5-dimethylphenyl)-5-methylhexan-2-one (8), respectively, in which the alkyl groups result from hydrogenation of the allyl ligand in the organometallic reactant. Complex 2 reacts similarly, but complex 3 only produces the ketone from its reaction with CO in benzene. Theoretical calculations indicate that the key mechanistic feature of these conversions is the formation of a 16e η2-alkene complex which is generated by the regiospecific migration of the hydride ligand onto the tertiary carbon of the allyl ligand. The 16e Cp*W(NO)(η2-CH2═CHCHMe2) and Cp*W(NO)(η2-MeCH═CHPh) intermediate complexes formed in this manner by complexes 1 and 3, respectively, have been trapped as the corresponding 18e CO adducts Cp*W(NO) (CO)(η2-CH2═CHCHMe2) (10) and Cp*W(NO) (CO)(η2-MeCH═CHPh) (11). All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of two isomers of 11 have been established by single-crystal X-ray crystallographic analyses. This new and facile method of synthesizing saturated unsymmetrical ketones via C–C bond formation not only is atom economical but also is part of a complete synthetic cycle, since Cp*W(NO)(CO)2 (4) is the final organometallic product formed in all cases, and it can be readily reconverted to the hydrido allyl reactants 1–3 in three steps via Cp*W(NO)Cl2. Journal Article Organometallics 34 16 4085 4092 American Chemical Society (ACS) 0276-7333 1520-6041 31 8 2015 2015-08-31 10.1021/acs.organomet.5b00537 COLLEGE NANME Engineering COLLEGE CODE EEN Swansea University 2017-03-28T10:56:08.0704768 2017-03-27T11:03:22.5940882 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised R. Baillie 1 G. Lefèvre 2 R. Wakeham 3 A. Holmes 4 P. Legzdins 5 Russell Wakeham 0000-0002-4304-0243 6
title Unsymmetrical Saturated Ketones Resulting from Activations of Hydrocarbon C(sp3)–H and C(sp2)–H Bonds Effected by Cp*W(NO)(H)(η3-allyl) Complexes
spellingShingle Unsymmetrical Saturated Ketones Resulting from Activations of Hydrocarbon C(sp3)–H and C(sp2)–H Bonds Effected by Cp*W(NO)(H)(η3-allyl) Complexes
Russell Wakeham
title_short Unsymmetrical Saturated Ketones Resulting from Activations of Hydrocarbon C(sp3)–H and C(sp2)–H Bonds Effected by Cp*W(NO)(H)(η3-allyl) Complexes
title_full Unsymmetrical Saturated Ketones Resulting from Activations of Hydrocarbon C(sp3)–H and C(sp2)–H Bonds Effected by Cp*W(NO)(H)(η3-allyl) Complexes
title_fullStr Unsymmetrical Saturated Ketones Resulting from Activations of Hydrocarbon C(sp3)–H and C(sp2)–H Bonds Effected by Cp*W(NO)(H)(η3-allyl) Complexes
title_full_unstemmed Unsymmetrical Saturated Ketones Resulting from Activations of Hydrocarbon C(sp3)–H and C(sp2)–H Bonds Effected by Cp*W(NO)(H)(η3-allyl) Complexes
title_sort Unsymmetrical Saturated Ketones Resulting from Activations of Hydrocarbon C(sp3)–H and C(sp2)–H Bonds Effected by Cp*W(NO)(H)(η3-allyl) Complexes
author_id_str_mv 28c45bbeeba294da7042950705b98e0a
author_id_fullname_str_mv 28c45bbeeba294da7042950705b98e0a_***_Russell Wakeham
author Russell Wakeham
author2 R. Baillie
G. Lefèvre
R. Wakeham
A. Holmes
P. Legzdins
Russell Wakeham
format Journal article
container_title Organometallics
container_volume 34
container_issue 16
container_start_page 4085
publishDate 2015
institution Swansea University
issn 0276-7333
1520-6041
doi_str_mv 10.1021/acs.organomet.5b00537
publisher American Chemical Society (ACS)
college_str Faculty of Science and Engineering
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hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 0
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description C–H activations of a C(sp2)–H bond in benzene or a C(sp3)–H bond in mesitylene at 80 °C under CO pressure in undried solvents without rigorous exclusion of air and moisture can be effected with the 18e complexes Cp*W(NO)(H)(η3-CH2CHCMe2) (1), Cp*W(NO)(H)(η3-CH2CHCHMe) (2), and Cp*W(NO)(H)(η3-CH2CHCHPh) (3) (Cp* = η5-C5Me5). These activations are regiospecific and afford in the case of complex 1 good yields of the unsymmetrical saturated ketones 4-methyl-1-phenylpentan-1-one (5) and 1-(3,5-dimethylphenyl)-5-methylhexan-2-one (8), respectively, in which the alkyl groups result from hydrogenation of the allyl ligand in the organometallic reactant. Complex 2 reacts similarly, but complex 3 only produces the ketone from its reaction with CO in benzene. Theoretical calculations indicate that the key mechanistic feature of these conversions is the formation of a 16e η2-alkene complex which is generated by the regiospecific migration of the hydride ligand onto the tertiary carbon of the allyl ligand. The 16e Cp*W(NO)(η2-CH2═CHCHMe2) and Cp*W(NO)(η2-MeCH═CHPh) intermediate complexes formed in this manner by complexes 1 and 3, respectively, have been trapped as the corresponding 18e CO adducts Cp*W(NO) (CO)(η2-CH2═CHCHMe2) (10) and Cp*W(NO) (CO)(η2-MeCH═CHPh) (11). All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of two isomers of 11 have been established by single-crystal X-ray crystallographic analyses. This new and facile method of synthesizing saturated unsymmetrical ketones via C–C bond formation not only is atom economical but also is part of a complete synthetic cycle, since Cp*W(NO)(CO)2 (4) is the final organometallic product formed in all cases, and it can be readily reconverted to the hydrido allyl reactants 1–3 in three steps via Cp*W(NO)Cl2.
published_date 2015-08-31T03:40:10Z
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score 11.036116