chapter 2 palladium catalysts in suzuki cross- coupling reaction
chapter 2 palladium catalysts in suzuki cross- coupling reaction
chapter 2 palladium catalysts in suzuki cross- coupling reaction
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ABSTRACT<br />
SHORT-TIME SUZUKI REACTIONS<br />
OF ARYL HALIDES CATALYZED BY PALLADIUM-LOADED<br />
NaY ZEOLITE UNDER AEROBIC CONDITIONS<br />
The <strong>palladium</strong>-catalyzed Suzuki <strong>cross</strong>-coupl<strong>in</strong>g <strong>reaction</strong> is a powerful methods<br />
used <strong>in</strong> the synthesis of biaryl compounds.<br />
In this study, the Suzuki <strong>reaction</strong>s of aryl bromides and chlorides with arylboronic<br />
acid were carried out over a Pd(NH3)4 2+ -loaded NaY type zeolite. On the basis of our<br />
results, the Pd(NH3)4 2+ -loaded NaY zeolite was found to be highly active for the Suzuki<br />
<strong>reaction</strong>s of wide range of aryl bromides and electron poor aryl chlorides at low Pd<br />
concentrations (0.1-0.001mol %Pd), <strong>in</strong> air and at short times (5-45 m<strong>in</strong>utes). The<br />
presence of relatively large amount of zeolite (1-4 g) was crucial for the success of the<br />
<strong>reaction</strong>s with aryl chlorides. It was determ<strong>in</strong>ed that there was a synergistic effect of the<br />
water- zeolite pair on the <strong>reaction</strong> rate.<br />
It was found that <strong>reaction</strong>s were catalyzed dissolved <strong>palladium</strong> species. However,<br />
the <strong>palladium</strong> was largely recovered and only traces of <strong>palladium</strong> rema<strong>in</strong>ed with<strong>in</strong> the<br />
solution at the end of <strong>reaction</strong> (