PDF herunterladen
Synlett 2008(15): 2313-2316  
DOI: 10.1055/s-2008-1078274
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Dihydroxylation of Olefins Catalyzed by Polystyrene-sg-imidazolium Resin-Supported Osmium Complex

Bong-Hyun Juna, Jong-Ho Kima,1, Juyoung Parka, Homan Kangb, Sang-Hyeup Lee*c, Yoon-Sik Lee*a,b
a School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Korea
Fax: +82(2)8769625; e-Mail: yslee@snu.ac.kr;
b Interdisciplinary Program in Nano-Science and Technology, Seoul National University, Seoul 151-747, Korea
c Department of Life Chemistry, Catholic University of Daegu, Gyeongsan 712-702, Korea
Weitere Informationen

Publikationsverlauf

Received 24 April 2008
Publikationsdatum:
21. August 2008 (online)

    Lizenzen und Reprints Alle Artikel dieser Rubrik

Abstract

Osmium tetroxide was immobilized onto an imidazolium-based polymer, poly(1-methylimidazoliummethyl styrene)-surface grafted-PS (PS-sg-IM) resin. In order to characterize the polymer-imidazolium-supported osmium-complex catalysts, Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray microanalysis (EDX), and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) experiments were carried out, and we verified that the formation of the osmium complex occurred only on the surface of the polymer support. This polymer catalysts was used in the dihydroxylation of various olefins, revealed excellent catalytic activity, and could be reused up to three times

Key words

osmium - imidazolium - heterogeneous catalysis

1

New address: J. H. Kim, Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

17

Preparation of Polystyrene-Surface-Grafted Imidazolium Resin-Supported Osmium (PS- sg -IM Os) Complex Poly(1-methylimidazolium-methyl styrene)-g-PS Resin (PS-sg-IM) was prepared following our published protocol. [¹³] The PS-sg-IM (100 mg, 0.37 mmol/g, 0.031 mmol) and K2OsO4˙2H2O (8.6 mg, 0.023 mmol, 0.6 equiv) were mixed and stirred in a mixture of H2O (1.2 mL) at 25 ˚C for 2 d. The resulting resin was filtered and washed vigorously with distilled H2O (5 × 10 mL), acetone (5 × 10 mL), and MeOH (5 × 10 mL). The resin was then dried in vacuo overnight to generate the polystyrene-sg-imidazolium resin-supported osmium (PS-sg-IM Os) complex (PS-sg-IM Os). The loading level of osmium on the polystyrene-imidazolium-based polymer was 0.178 mmol/g, which was analyzed by ICP-AES.

18

Typical Experimental Procedure for Dihydroxylation of Olefins Using PS- sg -IM Os
PS-sg-IM Os (56 mg, 1 mol% Os, 0.18 mmol-Os/g) was suspended in H2O-acetone (v/v, 1:3, 3 mL). To this suspension was added the olefin (1 mmol) and NMO (152 mg, 1.3 mmol), and the reaction mixture was agitated in a shaking incubator at 25 ˚C in an air atmosphere. The progress of the reaction was monitored by TLC. After consumption of the starting olefin, the resulting reaction mixture was filtered through polyethylene frit and washed with MeOH (5 × 10 mL). The combined filtrate was evaporated, and the resulting residue was purified by flash chromatography on SiO2 to afford the desired dihydroxylated product. All the products were characterized by ¹H NMR spectroscopy andGC-MS. All the dihydroxylated products are known, and their spectral data were in accordance with those reported in the literature. [9]

19

Reusability Test of PS- sg -IM Os
The DH reaction was performed at exactly the same scale using α-methylstyrene as a model substrate following the typical experimental procedure described above. After the consumption of α-methylstyrene (TLC), the mixture was filtered through polyethylene frit and washed with MeOH (5 × 10 mL). The dihydroxyated product was isolated from the combined filtrate by the method described in the previous section. The recovered catalyst was collected on the polyethylene frit, dried under a nitrogen stream, transferred back to the reaction flask, and was then reused two more times for the same reaction.