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Synlett 2007(14): 2267-2271  
DOI: 10.1055/s-2007-985584
LETTER
© Georg Thieme Verlag Stuttgart · New York

Practical Preparation of Diosphenols by Ring Opening of α,β-Epoxyketones Catalyzed by Silica Gel Supported Acids

Rui Zhu, Lixin Xing, Xinyan Wang, Chuanjie Cheng, Bo Liu, Yuefei Hu*
Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, P. R. of China
Fax: +86(10)62771149; e-Mail: yfh@mail.tsinghua.edu.cn;
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Publication History

Received 28 April 2007
Publication Date:
14 August 2007 (online)

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Abstract

The mixed acid (H2SO4-HOAc) catalyzed ring opening of α,β-epoxyketone was the most used method for the preparation of diosphenols, but it seriously suffered from poor yields and ­tedious workup operations. By using silica gel supported mixed acid (H2SO4-HOAc), a variety of α,β-epoxyketones were converted into the corresponding diosphenols in unprecedented high yields within a few minutes.

Key words

supported catalysis - regioselective - peroxides - ring opening - green chemistry

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Typical Procedure for the Preparation of 3d: The mixture of substrate 4d (1.0 g), the mixed acid [2.0 mL, H2SO4-HOAc (1:2 wt/wt)] and silica gel (8.0 g) in THF (10 mL) was rotaevaporated in vacuum (<15 mmHg) at 70 °C. After the solvent had been removed, the reaction was continued for another 3 min. The resultant non-stick solid was then washed with CH2Cl2 and the combined organic layers were washed with aq Na2CO3, brine and dried over Na2SO4. Removal of the solvent yielded the crude product, which was purified by chromatography to give the pure product 3d (0.81 g, 81%) as white crystals; mp 88-90 °C (EtOAc-PE); [α]D 20 +277.86° (c = 1.20, CHCl3). IR: 3386, 2958, 2937, 2871, 1739, 1661 cm-1. 1H NMR: δ = 6.17 (s, 1 H), 3.02-3.06 (m, 1 H), 2.61-2.75 (m, 4 H), 2.39-2.46 (m, 1 H), 2.07-2.09 (m, 1 H), 1.90-1.92 (m, 1 H), 1.32 (s, 3 H). 13C NMR: δ = 217.4, 193.7, 141.3, 137.2, 48.4, 35.7, 31.7, 29.6, 21.1, 20.7. MS: m/z (%) = 180 (100), 152 (21), 137 (19), 110 (19), 109 (35), 95 (18), 81 (31), 67 (34), 55 (23), 39 (28). Anal. Calcd for C10H12O3: C, 66.65; H, 6.71. Found: C, 66.58; H, 6.70. The same proce-dure was efficiently used to convert the substrates 4a-j into the corresponding products 3a-j (see Table [2] ). Products 3a-j are known compounds and their 1H NMR and 13C NMR spectra are available upon request from the authors.