added slowly, and the resulting red mixture was stirred at −78 ◦C
for 1 h. The mixture was quenched with the corresponding
electrophile (Table 2). Work-up followed the procedure as detailed
above (chromatographic purification was not required).
Experimental
General
Sodium powder was obtained, from ACROS chemicals, as a
slurry in toluene (30 wt%, <0.1 mm particle size). The sodium
powder was filtered and dried in vacuo and stored under argon,
prior to use. All other chemicals were obtained from Aldrich
or Fluka and used without purification. Reagent-grade THF
was dried (Na wire), distilled (Na/K benzophenone) and freeze-
degassed prior to use. 2-(3ꢀ-Chloropropyl)-2-methyl-1,3-dioxalane
was prepared from 5-chloro-2-pentanone following literature
procedures.15 Polymer-supported naphthalene (P152) was pre-
pared from vinylnaphthalene (1 mol equiv.), styrene (5 mol equiv.),
divinylbenzene (2 mol equiv.) and polyvinyl alcohol in water,
following the Itsuno methodology to give crosslinked polymers.6,16
All reactions utilising sodium powder were carried out in flame-
dried, evacuated glassware under an inert atmosphere of high
purity argon. 1H NMR spectra were recorded on a Varian Gemini
200 spectrophotometer operating at 200 MHz with CDCl3 as
solvent.
General procedure for the testing of the activity of spent polymer
A yellow–green suspension of sodium powder (0.44 g, 19.0 mmol)
and polymer-supported naphthalene (0.4–8.0 mmol) in THF
(60 mL) was stirred for 20 min at −78 ◦C. Chlorobenzene
(8.0 mmol) in THF (40 mL) was then added slowly, and the
resulting red mixture was stirred at −78 ◦C for 1 h. The excess of
sodium powder and polymer-supported naphthalene was filtered,
at −78 ◦C, affording a red solution of phenylsodium. The activity
of the solution was determined by titration. The isolated spent
polymer was washed with water (to remove any remaining sodium
powder), hexane, THF, and dried in vacuo. The polymer was
then re-treated with sodium powder, THF and chlorobenzene, to
regenerate phenylsodium. This process was subsequently repeated
once again with the clean, dried, spent polymer.
Acknowledgements
General procedure for the synthesis of sodium reagents using
naphthalene
We thank USQ for support of this project.
In a typical experiment: To a cooled (−78 ◦C) dark green
suspension of sodium powder (0.27 g, 11.7 mmol) and naphthalene
(0.005 g, 0.22 mmol) in THF (60 mL), was slowly added a
solution of organochloride (4.0 mmol) in THF (40 mL), and the
resulting coloured mixture was stirred at −78 ◦C for 1 h. (The
excess of sodium powder was filtered, at −78 ◦C, affording the
coloured organosodium reagent. The activity of the solution was
determined by titration.) The sodium reagent was then quenched
by the slow addition, over 5 min, of the desired electrophile
(H2O, ClSiMe3, PriCHO or (CH2)5CO; see Table 1), and the
mixture stirred overnight, gradually warming the solution to room
temperature. The resulting solutions were subsequently hydrolysed
(MeOH, HCl), extracted into diethyl ether and/or hexane, filtered,
dried over anhydrous Na2SO4 and the solvent removed in vacuo,
affording the desired product. Alternatively the desired product
was distilled from the solvent. Purification, if required, of the
desired product was achieved by column chromatography (silica
gel, hexane–ethyl acetate 9 : 1). The purity of the isolated products
were determined by 1H NMR and compared to literature values.
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General procedure for the synthesis of sodium reagents using
polymer-supported naphthalene
In a typical experiment: A yellow–green suspension of sodium
powder (0.44 g, 19.0 mmol) and polymer-supported naphthalene
(0.4–8.0 mmol) in THF (60 mL) was stirred for 20 min at
−78 ◦C. Chlorobenzene (8.0 mmol) in THF (40 mL) was then
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