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Synthesis of 18? annulenic fluorofullerenes from tertiary carbanions: size matters!

Synthesis of 18? annulenic fluorofullerenes from tertiary carbanions: size matters!
Synthesis of 18? annulenic fluorofullerenes from tertiary carbanions: size matters!
A range of tertiary carbanions XCH(CO2Et)2 of differing sizes have been reacted with C60F18 to assess the steric effect of X on the position of nucleophilic substitution. For X= CO2Et, NO2, P(O)(OMe)2, SO2CH2Ph, the all trans annulenes (trannulenes) were obtained as a result of extended SN2'(i.e. SN2'') substitution; in the case of the phosphorus compound, with reduced amounts of base (DBU) dephosphonylation of one or more P(O)(OMe)2 groups by hydrogen occurred. Trannulene formation did not occur for X= F, CN due to the smaller size of the nucleophile, and in the latter case substitution was shown to take place by an SN2' mechanism, resulting in the addend being adjacent to a fluorine addend. Trannulenes (X= CO2Et, Br, Cl) exhibited reversible one-electron reductions at potentials (–0.02 to –0.09 V) significantly more positive than for [60]fullerene. Trannulene (X= NO2) exhibited an irreversible one-electron reduction (0.08 V); the irreversibility may be associated with fluorine loss. Conformational isomerism at temperatures below 298 K was observed for all trannulene derivatives as a result of eclipsing addend–addend interactions. Minimum energy conformations with a rotational energy barrier of 12–15 kcal mol–1 were observed when these interactions are calculated using molecular mechanics.
c60f18
1477-0520
2015-2023
Burley, Glenn A.
ccedea82-73a7-454b-b718-b2d6a56ca28b
Avent, Anthony G.
6fe5d51d-5f31-454f-938a-ec91c840f2ce
Boltalina, Olga V.
7fefd47c-6427-4d51-8d9f-e1b116daad8c
Drewello, Thomas
a908a5f8-c364-4575-9515-fd130e29bffc
Goldt, Ilya V.
a75319da-e101-410f-a99c-a3c2d56fd8e6
Marcaccio, Massimo
07912884-0f6d-45b1-8a60-f9f7eda8983d
Paolucci, Francesco
073b630d-7adc-41ee-b198-6b33bcacce6c
Paolucci, Demis
9157555c-1792-4a4b-b9a3-1cc4d17cc6df
Street, Joan M.
186366c0-692b-4236-bb93-e2a3b6e9395c
Taylor, Roger
16cca243-6646-4c6f-a563-321c2b1bb0f6
Burley, Glenn A.
ccedea82-73a7-454b-b718-b2d6a56ca28b
Avent, Anthony G.
6fe5d51d-5f31-454f-938a-ec91c840f2ce
Boltalina, Olga V.
7fefd47c-6427-4d51-8d9f-e1b116daad8c
Drewello, Thomas
a908a5f8-c364-4575-9515-fd130e29bffc
Goldt, Ilya V.
a75319da-e101-410f-a99c-a3c2d56fd8e6
Marcaccio, Massimo
07912884-0f6d-45b1-8a60-f9f7eda8983d
Paolucci, Francesco
073b630d-7adc-41ee-b198-6b33bcacce6c
Paolucci, Demis
9157555c-1792-4a4b-b9a3-1cc4d17cc6df
Street, Joan M.
186366c0-692b-4236-bb93-e2a3b6e9395c
Taylor, Roger
16cca243-6646-4c6f-a563-321c2b1bb0f6

Burley, Glenn A., Avent, Anthony G., Boltalina, Olga V., Drewello, Thomas, Goldt, Ilya V., Marcaccio, Massimo, Paolucci, Francesco, Paolucci, Demis, Street, Joan M. and Taylor, Roger (2003) Synthesis of 18? annulenic fluorofullerenes from tertiary carbanions: size matters! Organic & Biomolecular Chemistry, 1 (11), 2015-2023. (doi:10.1039/b301820m).

Record type: Article

Abstract

A range of tertiary carbanions XCH(CO2Et)2 of differing sizes have been reacted with C60F18 to assess the steric effect of X on the position of nucleophilic substitution. For X= CO2Et, NO2, P(O)(OMe)2, SO2CH2Ph, the all trans annulenes (trannulenes) were obtained as a result of extended SN2'(i.e. SN2'') substitution; in the case of the phosphorus compound, with reduced amounts of base (DBU) dephosphonylation of one or more P(O)(OMe)2 groups by hydrogen occurred. Trannulene formation did not occur for X= F, CN due to the smaller size of the nucleophile, and in the latter case substitution was shown to take place by an SN2' mechanism, resulting in the addend being adjacent to a fluorine addend. Trannulenes (X= CO2Et, Br, Cl) exhibited reversible one-electron reductions at potentials (–0.02 to –0.09 V) significantly more positive than for [60]fullerene. Trannulene (X= NO2) exhibited an irreversible one-electron reduction (0.08 V); the irreversibility may be associated with fluorine loss. Conformational isomerism at temperatures below 298 K was observed for all trannulene derivatives as a result of eclipsing addend–addend interactions. Minimum energy conformations with a rotational energy barrier of 12–15 kcal mol–1 were observed when these interactions are calculated using molecular mechanics.

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Published date: 2003
Keywords: c60f18

Identifiers

Local EPrints ID: 19919
URI: https://eprints.soton.ac.uk/id/eprint/19919
ISSN: 1477-0520
PURE UUID: d9e7d7ad-3851-45e7-8792-f5e623297ff5

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Date deposited: 23 Feb 2006
Last modified: 15 Jul 2019 19:26

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Contributors

Author: Glenn A. Burley
Author: Anthony G. Avent
Author: Olga V. Boltalina
Author: Thomas Drewello
Author: Ilya V. Goldt
Author: Massimo Marcaccio
Author: Francesco Paolucci
Author: Demis Paolucci
Author: Joan M. Street
Author: Roger Taylor

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