Towards the functionalization of the methine carbon of a sterically hindered tris(pyrazolyl)methane: is a radical pathway envisageable? Synthesis and structure of tetrakis(3,5-dimethylpyrazolyl)methane

Laurent Benisvy; Riccardo Wanke; Maxim L. Kuznetsov; M. Fátima C. Guedes da Silva; Armando J.L. Pombeiro

doi:10.1016/j.tet.2009.09.006

Towards the functionalization of the methine carbon of a sterically hindered tris(pyrazolyl)methane: is a radical pathway envisageable? Synthesis and structure of tetrakis(3,5-dimethylpyrazolyl)methane

Laurent Benisvy, Riccardo Wanke, Maxim L. Kuznetsov, M. Fátima C. Guedes da Silva, Armando J.L. Pombeiro

Department of Chemistry

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

15 Scopus citations

Abstract

Iodine oxidation, at -80 °C, of the carbanion in [{^-C(pz^Me2)₃}Li⁺(THF)] (1) (with pz^Me2=3,5-dimethylpyrazolyl) yields the C-centred radical in [{^{{radical dot}}C(pz^Me2)₃}Li(THF)]⁺ (1⁺), which, upon warming to room temperature, produces the unprecedented tetrakis(3,5-dimethylpyrazolyl)methane C(pz^Me2)₄ (3), the X-ray structure of which revealing intramolecular C-H⋯π interactions between each 5-Me group and an adjacent pyrazolyl ring. Oxidation of the radical by O₂ appears to lead to the novel ether (pz^Me2)₃C-O-C(pz^Me2)₃ (2).

Original language	English
Pages (from-to)	9218-9223
Number of pages	6
Journal	Tetrahedron
Volume	65
Issue number	45
DOIs	https://doi.org/10.1016/j.tet.2009.09.006
State	Published - 7 Nov 2009

Bibliographical note

Funding Information:
This work has been partially supported by the Foundation for Science and Technology (FCT), and its POCI 2010 programmes (FEDER funded), grant SFRH/BD/23187/2005 (R.W.), as well as by the Human Resources and Mobility Marie Curie Research Training Network (AQUACHEM project, CMTN-CT-2003-503864). L.B. thanks the EU for the provision of an ER fellowship within this project. M.L.K. is grateful to the FCT and IST for a research contract within the Ciência 2007 scientific programme.

Keywords

Carbanion
DFT calculations
Oxidation
Radical
Tris(pyrazolyl)methane

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10.1016/j.tet.2009.09.006

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Benisvy, L., Wanke, R., Kuznetsov, M. L., Guedes da Silva, M. F. C., & Pombeiro, A. J. L. (2009). Towards the functionalization of the methine carbon of a sterically hindered tris(pyrazolyl)methane: is a radical pathway envisageable? Synthesis and structure of tetrakis(3,5-dimethylpyrazolyl)methane. Tetrahedron, 65(45), 9218-9223. https://doi.org/10.1016/j.tet.2009.09.006

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title = "Towards the functionalization of the methine carbon of a sterically hindered tris(pyrazolyl)methane: is a radical pathway envisageable? Synthesis and structure of tetrakis(3,5-dimethylpyrazolyl)methane",

abstract = "Iodine oxidation, at -80 °C, of the carbanion in [{-C(pzMe2)3}Li+(THF)] (1) (with pzMe2=3,5-dimethylpyrazolyl) yields the C-centred radical in [{{radical dot}C(pzMe2)3}Li(THF)]+ (1+), which, upon warming to room temperature, produces the unprecedented tetrakis(3,5-dimethylpyrazolyl)methane C(pzMe2)4 (3), the X-ray structure of which revealing intramolecular C-H⋯π interactions between each 5-Me group and an adjacent pyrazolyl ring. Oxidation of the radical by O2 appears to lead to the novel ether (pzMe2)3C-O-C(pzMe2)3 (2).",

keywords = "Carbanion, DFT calculations, Oxidation, Radical, Tris(pyrazolyl)methane",

author = "Laurent Benisvy and Riccardo Wanke and Kuznetsov, {Maxim L.} and {Guedes da Silva}, {M. F{\'a}tima C.} and Pombeiro, {Armando J.L.}",

note = "Funding Information: This work has been partially supported by the Foundation for Science and Technology (FCT), and its POCI 2010 programmes (FEDER funded), grant SFRH/BD/23187/2005 (R.W.), as well as by the Human Resources and Mobility Marie Curie Research Training Network (AQUACHEM project, CMTN-CT-2003-503864). L.B. thanks the EU for the provision of an ER fellowship within this project. M.L.K. is grateful to the FCT and IST for a research contract within the Ci{\^e}ncia 2007 scientific programme. ",

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Benisvy, L, Wanke, R, Kuznetsov, ML, Guedes da Silva, MFC & Pombeiro, AJL 2009, 'Towards the functionalization of the methine carbon of a sterically hindered tris(pyrazolyl)methane: is a radical pathway envisageable? Synthesis and structure of tetrakis(3,5-dimethylpyrazolyl)methane', Tetrahedron, vol. 65, no. 45, pp. 9218-9223. https://doi.org/10.1016/j.tet.2009.09.006

Towards the functionalization of the methine carbon of a sterically hindered tris(pyrazolyl)methane: is a radical pathway envisageable? Synthesis and structure of tetrakis(3,5-dimethylpyrazolyl)methane. / Benisvy, Laurent; Wanke, Riccardo; Kuznetsov, Maxim L. et al.
In: Tetrahedron, Vol. 65, No. 45, 07.11.2009, p. 9218-9223.

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

TY - JOUR

T1 - Towards the functionalization of the methine carbon of a sterically hindered tris(pyrazolyl)methane

T2 - is a radical pathway envisageable? Synthesis and structure of tetrakis(3,5-dimethylpyrazolyl)methane

AU - Benisvy, Laurent

AU - Wanke, Riccardo

AU - Kuznetsov, Maxim L.

AU - Guedes da Silva, M. Fátima C.

AU - Pombeiro, Armando J.L.

N1 - Funding Information: This work has been partially supported by the Foundation for Science and Technology (FCT), and its POCI 2010 programmes (FEDER funded), grant SFRH/BD/23187/2005 (R.W.), as well as by the Human Resources and Mobility Marie Curie Research Training Network (AQUACHEM project, CMTN-CT-2003-503864). L.B. thanks the EU for the provision of an ER fellowship within this project. M.L.K. is grateful to the FCT and IST for a research contract within the Ciência 2007 scientific programme.

PY - 2009/11/7

Y1 - 2009/11/7

N2 - Iodine oxidation, at -80 °C, of the carbanion in [{-C(pzMe2)3}Li+(THF)] (1) (with pzMe2=3,5-dimethylpyrazolyl) yields the C-centred radical in [{{radical dot}C(pzMe2)3}Li(THF)]+ (1+), which, upon warming to room temperature, produces the unprecedented tetrakis(3,5-dimethylpyrazolyl)methane C(pzMe2)4 (3), the X-ray structure of which revealing intramolecular C-H⋯π interactions between each 5-Me group and an adjacent pyrazolyl ring. Oxidation of the radical by O2 appears to lead to the novel ether (pzMe2)3C-O-C(pzMe2)3 (2).

AB - Iodine oxidation, at -80 °C, of the carbanion in [{-C(pzMe2)3}Li+(THF)] (1) (with pzMe2=3,5-dimethylpyrazolyl) yields the C-centred radical in [{{radical dot}C(pzMe2)3}Li(THF)]+ (1+), which, upon warming to room temperature, produces the unprecedented tetrakis(3,5-dimethylpyrazolyl)methane C(pzMe2)4 (3), the X-ray structure of which revealing intramolecular C-H⋯π interactions between each 5-Me group and an adjacent pyrazolyl ring. Oxidation of the radical by O2 appears to lead to the novel ether (pzMe2)3C-O-C(pzMe2)3 (2).

KW - Carbanion

KW - DFT calculations

KW - Oxidation

KW - Radical

KW - Tris(pyrazolyl)methane

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SN - 0040-4020

VL - 65

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JO - Tetrahedron

JF - Tetrahedron

IS - 45

ER -

Towards the functionalization of the methine carbon of a sterically hindered tris(pyrazolyl)methane: is a radical pathway envisageable? Synthesis and structure of tetrakis(3,5-dimethylpyrazolyl)methane

Abstract

Bibliographical note

Keywords

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