The value of 2JP–CO as a diagnostic parameter for the structure and thermal reactivity of carbonyl-stablised phosphonium ylides

R. Alan Aitken; Youcef Boubalouta; Da Chang; Lee P. Cleghorn; Ian P. Gray; Nazira Karodia; Euan J. Reid; Alexandra M. Z. Slawin

doi:10.1016/j.tet.2017.09.016

The value of ²J_P–CO as a diagnostic parameter for the structure and thermal reactivity of carbonyl-stablised phosphonium ylides

R. Alan Aitken
, Youcef Boubalouta
, Da Chang
, Lee P. Cleghorn
, Ian P. Gray
, Nazira Karodia
, Euan J. Reid
, Alexandra M. Z. Slawin

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

Abstract

A survey of 20 carbonyl-stabilised phosphonium ylides with recently reported X-ray structures shows a strong correlation between the C=P to C=O torsion angle and the value of ²J_P–CO, with high values being associated with an anti configuration and low with syn. Seven new X-ray structural determinations are reported, several for types of ylide not crystallograpically characterised before, and these also conform to this pattern. The value of ²J_P–CO is then correlated with whether or not thermal extrusion of Ph₃PO occurs to give alkynes for over 200 ylides and an empirical rule developed that the extrusion never occurs for ylides where this value is >11 Hz. This is used to rationalise the anomalous behaviour of some trioxo ylides and cyclic ylides, two of which afford cycloalkynes, isolated after rearrangement as the isomeric 1,3-dienes. The rule also holds for a family of novel highly fluorinated ylides which afford fluorinated alkynes in good yield upon flash vacuum pyrolysis.

Original language	English
Pages (from-to)	6275-6285
Number of pages	11
Journal	Tetrahedron
Volume	73
Issue number	44
Early online date	18 Sept 2017
DOIs	https://doi.org/10.1016/j.tet.2017.09.016
Publication status	Published - 2 Nov 2017

Keywords

Ylides
X-ray structure
NMR coupling constants
Pyrolysis
Cycloalkynes

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© 2017 Elsevier Ltd. 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 may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1016/j.tet.2017.09.016
Accepted author manuscript, 1.36 MBLicence: CC BY-NC-ND

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@article{578bb4579716491d920397e6380cb3bc,

title = "The value of 2JP–CO as a diagnostic parameter for the structure and thermal reactivity of carbonyl-stablised phosphonium ylides",

abstract = "A survey of 20 carbonyl-stabilised phosphonium ylides with recently reported X-ray structures shows a strong correlation between the C=P to C=O torsion angle and the value of 2JP–CO, with high values being associated with an anti configuration and low with syn. Seven new X-ray structural determinations are reported, several for types of ylide not crystallograpically characterised before, and these also conform to this pattern. The value of 2JP–CO is then correlated with whether or not thermal extrusion of Ph3PO occurs to give alkynes for over 200 ylides and an empirical rule developed that the extrusion never occurs for ylides where this value is >11 Hz. This is used to rationalise the anomalous behaviour of some trioxo ylides and cyclic ylides, two of which afford cycloalkynes, isolated after rearrangement as the isomeric 1,3-dienes. The rule also holds for a family of novel highly fluorinated ylides which afford fluorinated alkynes in good yield upon flash vacuum pyrolysis.",

keywords = "Ylides, X-ray structure, NMR coupling constants, Pyrolysis, Cycloalkynes",

author = "Aitken, \{R. Alan\} and Youcef Boubalouta and Da Chang and Cleghorn, \{Lee P.\} and Gray, \{Ian P.\} and Nazira Karodia and Reid, \{Euan J.\} and Slawin, \{Alexandra M. Z.\}",

note = "The authors thank the EPSRC (U.K.) for a DTA Studentship (Grant No. EP/P505712/1)",

year = "2017",

month = nov,

day = "2",

doi = "10.1016/j.tet.2017.09.016",

language = "English",

volume = "73",

pages = "6275--6285",

journal = "Tetrahedron",

issn = "0040-4020",

publisher = "Elsevier",

number = "44",

}

TY - JOUR

T1 - The value of 2JP–CO as a diagnostic parameter for the structure and thermal reactivity of carbonyl-stablised phosphonium ylides

AU - Aitken, R. Alan

AU - Boubalouta, Youcef

AU - Chang, Da

AU - Cleghorn, Lee P.

AU - Gray, Ian P.

AU - Karodia, Nazira

AU - Reid, Euan J.

AU - Slawin, Alexandra M. Z.

N1 - The authors thank the EPSRC (U.K.) for a DTA Studentship (Grant No. EP/P505712/1)

PY - 2017/11/2

Y1 - 2017/11/2

N2 - A survey of 20 carbonyl-stabilised phosphonium ylides with recently reported X-ray structures shows a strong correlation between the C=P to C=O torsion angle and the value of 2JP–CO, with high values being associated with an anti configuration and low with syn. Seven new X-ray structural determinations are reported, several for types of ylide not crystallograpically characterised before, and these also conform to this pattern. The value of 2JP–CO is then correlated with whether or not thermal extrusion of Ph3PO occurs to give alkynes for over 200 ylides and an empirical rule developed that the extrusion never occurs for ylides where this value is >11 Hz. This is used to rationalise the anomalous behaviour of some trioxo ylides and cyclic ylides, two of which afford cycloalkynes, isolated after rearrangement as the isomeric 1,3-dienes. The rule also holds for a family of novel highly fluorinated ylides which afford fluorinated alkynes in good yield upon flash vacuum pyrolysis.

AB - A survey of 20 carbonyl-stabilised phosphonium ylides with recently reported X-ray structures shows a strong correlation between the C=P to C=O torsion angle and the value of 2JP–CO, with high values being associated with an anti configuration and low with syn. Seven new X-ray structural determinations are reported, several for types of ylide not crystallograpically characterised before, and these also conform to this pattern. The value of 2JP–CO is then correlated with whether or not thermal extrusion of Ph3PO occurs to give alkynes for over 200 ylides and an empirical rule developed that the extrusion never occurs for ylides where this value is >11 Hz. This is used to rationalise the anomalous behaviour of some trioxo ylides and cyclic ylides, two of which afford cycloalkynes, isolated after rearrangement as the isomeric 1,3-dienes. The rule also holds for a family of novel highly fluorinated ylides which afford fluorinated alkynes in good yield upon flash vacuum pyrolysis.

KW - Ylides

KW - X-ray structure

KW - NMR coupling constants

KW - Pyrolysis

KW - Cycloalkynes

UR - http://www.sciencedirect.com/science/article/pii/S0040402017309389#appd001

U2 - 10.1016/j.tet.2017.09.016

DO - 10.1016/j.tet.2017.09.016

M3 - Article

SN - 0040-4020

VL - 73

SP - 6275

EP - 6285

JO - Tetrahedron

JF - Tetrahedron

IS - 44

ER -

The value of ²J_P–CO as a diagnostic parameter for the structure and thermal reactivity of carbonyl-stablised phosphonium ylides

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