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Synfacts 2009(4): 0462-0462  
DOI: 10.1055/s-0028-1087856
Polymer-Supported Synthesis
© Georg Thieme Verlag Stuttgart ˙ New York

cis-Product Formation by Imprinted Palladium Silicate Promoted Heck Reaction

Contributor(s): Yasuhiro Uozumi, Yoichi M. A. Yamada
D. Tsvelikhovsky, D. Pessing, D. Avnir*, J. Blum*
The Hebrew University, Jerusalem, Israel
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Publication History

Publication Date:
23 March 2009 (online)

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Significance

In general, the Mizoroki-Heck reaction of aryl bromides with styrene gave trans-stilbenes exclusively. This time, cis-stilbene-imprinted Pd(OAc)2 catalysts 1 supported onto octylated silicates were developed, which afforded cis-stilbenes 4 in up to 86% yield. Thus, hydrolysis and polycondensation of tetrameth­oxysilane and octyltriethoxysilane with Pd(OAc)2 and cis-stilbenes 4 (R¹,<R² = H or Me) followed by removal of 4 through extraction afforded ceramic material 1a-c. The Mizoroki-Heck reaction of 2a with 3a promoted by 1a under microemulsion conditions in water gave cis- and trans-stilbenes 4a and 5a in >99% conversion with 86:14 cis/trans selectivity.