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Topic: Doing steric demanding Ullmann or Suzuki coupling  (Read 2433 times)

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Offline kamiyu

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Doing steric demanding Ullmann or Suzuki coupling
« on: October 27, 2014, 10:56:59 AM »
Is there anyone here with experience of Suzuki (or Ullmann) coupling with sterically hindered substrates?

I am doing coupling between carbazole and 9-bromoanthracene

What is the most important factor to boost the yield of such reaction???

Thanks
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Offline C-hemCards

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Re: Doing steric demanding Ullmann or Suzuki coupling
« Reply #1 on: October 27, 2014, 10:06:57 PM »
Draw and think about each intermediate, including the ligand on the metal. Then, ask yourself how to minimize the energy required to proceed through each step of the mechanism.
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Offline BobfromNC

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Re: Doing steric demanding Ullmann or Suzuki coupling
« Reply #2 on: October 30, 2014, 02:21:32 PM »
Try a microwave reaction tube - ie, higher temperatures and pressure. 

Go to hottest reagent possible, iodide or triflate rather than bromide.

If that fails, try heating even more.   But keep it air free, any oxygen will kill you as you go up in temp. 
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