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Synlett 2007(4): 0619-0622  
DOI: 10.1055/s-2007-970745
LETTER
© Georg Thieme Verlag Stuttgart · New York

An Efficient and Green Oxidation of Vicinal Diols to Aldehydes Using Polymer-Supported (Diacetoxyiodo)benzene as the Oxidant

Fen-Er Chen*, Bin Xie, Ping Zhang, Jian-Feng Zhao, Hui Wang, Lei Zhao
Department of Chemistry, Fudan University, Shanghai 200433, P. R. of China
Fax: +86(21)65643811; e-Mail: rfchen@fudan.edu.cn;
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Publication History

Received 18 September 2006
Publication Date:
21 February 2007 (online)

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Abstract

An operationally simple and clean oxidation of a variety of vicinal diols to aldehydes using polymer-supported (diacetoxyiodo)benzene (PSDIB) has been developed in high to excellent yields. Protecting groups such as OAc, OR, OBn, OBz and iso­propylidene in the substrates were found to be stable under these reaction conditions. The regenerated PSDIB could be reused for the same reaction, affording oxidation products in high yield and purity.

Key words

polymer-supported (diacetoxyiodo)benzene - vicinal diols - oxidative cleavage - aldehydes

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Preparation of the Polymer-Supported (Diacetoxy-iodo)benzene (PSDIB).
To a mixture of CCl4 (20 mL), H2SO4 (50%, 20 mL) and nitrobenzene (100 mL) was added polystyrene (5.0 g), I2 (5.0 g, 19.7 mmol) and I2O5 (4.0 g, 12 mmol) at r.t. The reaction mixture was stirred under reflux for 50 h. After cooling to r.t., MeOH (500 mL) was added into the reaction mixture. The precipitates were collected by filtration and washed with MeOH (2 × 20 mL) and dried in vacuo to afford iodinated polystyrene (6.2 g). To Ac2O (145 mL, 1.54 mol) was added dropwise 30% H2O2 (40 mL, 0.35 mol) and the solution was stirred at 40 °C for 4 h. Then iodinated polystyrene (6.2 g) was added and stirring was continued overnight at the same temperature. After cooling the mixture to r.t., Et2O (100 mL) was added into the mixture. The precipitates were collected by filtration, washed with Et2O (2 × 20 mL) and dried in vacuo to give PSDIB (6.5 g). The loading rate of functional group is 1.98 mmol/g (determined by elemental analysis).

30

Oxidation of 1a.
To a solution of 1a (3.1 g, 10 mmol) in CH2Cl2 (40 mL) was added PSDIB (6.06 g, 12 mmol). Then, the reaction mixture was stirred at r.t. for 7 h. Thereafter, the polymer was filtered and washed with CH2Cl2 (3 × 8 mL). The filtrate was poured into H2O (45 mL), and extracted with CH2Cl2 (3 × 10 mL). The combined organic layer was washed with H2O (3 × 10 mL), dried over Na2SO4, filtered, and the solvent was evaporated in vacuo to give crude product, which was recrystallized from PE (60-90) to afford pure 2a (2.5 g, 90%) as a white powder; mp 81.5-83 °C; [α]D 25 +28.2 (c 1.0, acetone). IR (KBr): ν = 2935, 1750, 1361, 749 cm-1. 1H NMR (400 MHz, CDCl3): δ = 1.26, 1.40 (s, each 3 H, i-Pr), 4.42 (d, 1 H, J = 4 Hz, C3-H), 4.49 (d, J = 1 H, 12 Hz, C2-H), 4.67 (t, 2 H, J = 5.6 Hz, CH2C6H5), 5.07 (dd, 1 H, J = 4.8, 5.6 Hz, C4-H), 5.27 (s, 1 H, C1-H), 7.26-7.35 (m, 5 H, ArH), 9.65 (s, 1 H, CHO). GCMS: m/z (%) = 263 [M - CH3]+, 187, 129, 113, 91 (100).