LETTER
Macroporous Polystyrene-Supported (Diacetoxyiodo)benzene
69
K.-W.; Shi, M.; Toy, P. H. Tetrahedron 2005, 61, 12026.
(d) He, H. S.; Yan, J. J.; Shen, R.; Zhuo, S.; Toy, P. H.
Synlett 2006, 563.
One such application would be the high-throughput,
parallel oxidation of primary alcohols to the correspond-
ing carboxylic acids. Furthermore, the use of this new
reagent in conjunction with cross-linked polystyrene-sup-
ported triphenylphosphine in organocatalytic Mitsunobu
reactions is currently under investigation.
(21) Wang, G. P.; Chen, Z. C. Synth. Commun. 1999, 29, 2859.
(22) (a) Huang, X.; Zhu, Q. J. Chem. Res., Synop. 2000, 300.
(b) Zhang, J.-Z.; Zhu, Q.; Huang, X. Synth. Commun. 2002,
32, 2175.
(23) Ficht, S.; Mülbaier, M.; Giannis, A. Tetrahedron 2001, 57,
4863.
Acknowledgment
(24) Lee, J.-W.; Ko, K.-Y. Bull. Korean Chem. Soc. 2004, 25, 19.
(26) We have previously reported the use of a macroporous
polystyrenesulfonic acid reagent: Ueno, M.; Togo, H.
Synthesis 2004, 2673.
This research was supported financially by the Research Grants
Council of the Hong Kong Special Administrative Region, P. R. of
China (Project No. HKU 7027/03P) and by gifts of materials from
Polymer Laboratories.
(27) Preparation of 3
A solution of I2 (22.40 g, 88.20 mmol) in nitrobenzene (250
mL) and CCl4 (40 mL) was added to macroporous cross-
linked polystyrene (20.00 g), followed by a solution of I2O5
(8.76 g, 27.56 mmol) in 50% H2SO4 (44 mL). The reaction
mixture was stirred for 4 d at 85 °C. The reaction mixture
was then cooled to r.t., diluted with CHCl3–MeOH (1:15,
300 mL), and filtered. The collected polymer was washed
sequentially with H2O (3 × 200 mL), AcOH (2 × 200 mL),
CHCl3 (3 × 200 mL) and MeOH (3 × 200 mL) and dried in
vacuo to afford iodinated polymer (27.64 g). IR: 2932, 1526,
1340, 1184, 999, 819, 812, 703 cm–1. Elemental analysis of
the product showed the iodine content to be 24.63%, which
corresponds to a loading of 1.9 mmol/g.
References and Notes
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The iodinated macroporous cross-linked polystyrene (27.0
g)was added to a solution of peracetic acid generated by the
dropwise addition of H2O2 (30%, 136 mL) dropwise to Ac2O
(500 mL) at 0 °C, which was then allowed to warm to r.t. The
suspension was stirred at 40 °C for 16 h and then filtered.
The collected polymer was washed with Et2O (3 × 200 mL)
and dried in vacuo to afford 3 (33.0 g). IR: 2930, 1630, 1587,
1483, 1234, 818, 812, 702 cm–1. Elemental analysis of the
product showed the iodine content: 16.68%, which
corresponds to a loading of 1.3 mmol/g. The decrease in
loading level from 1.9 mmol/g to 1.3 mmol/g indicates
essentially quantitative oxidation of the iodine groups on the
polymer and both loading levels indicate that approximately
45% of the aryl rings of the polymer were functionalized.
(28) This was calculated by determining the ratios of the iodine
content of the iodinated polymer (24.63%) to that of 4-
ethyliodobenzene (54.69%), and the iodine content of 3
(16.68%) to that of 4-ethyl(diacetoxyiodo)benzene
(36.24%). The first ratio (0.45:1) indicates that
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approximately 45% of the aryl rings of the starting material
polymer were iodinated and the second ratio (0.46:1)
indicates that essentially all of the iodo groups were
oxidized.
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(31) Oxidation of Alcohols to the Corresponding Aldehydes
and Ketones (Table 1, Entries 1–6)
Reagent 3 (0.5 g, 0.65 mmol) was added to a solution of
alcohol (0.5 mmol) and TEMPO (9.4 mg, 0.06 mmol) in
acetone (3 mL) and the mixture was stirred at r.t. for 2 h. The
reaction mixture was then filtered to remove the polymer,
which was washed with Et2O (5 mL). The filtrate was poured
into H2O (10 mL), and extracted with Et2O (3 × 10 mL). The
combined organic layers were dried over Na2SO4, filtered,
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Synlett 2007, No. 1, 67–70 © Thieme Stuttgart · New York