I am looking precisely at a coupling of a trifluoroborate with an aryl bromide. I know the mechanism of the Suzuki reaction, yet I cannot find any mention of the side products or degradation products that one could obtain if the coupling fails. Maybe those products are obvious for those who know well how palladium reacts, but this is not my case. I tried to find a book that would give me a feel for what might happen and could find anything close enough.

I'm expecting a protodeboration as a side reaction, yet I can't find any source nor mechanism. Could anyone shed some light on the subject?

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    $\begingroup$ I believe homocoupling of the aryl bromide is a minor byproduct. There is enough literature on the reaction, but the information may be tucked away in the supporting info $\endgroup$ – Beerhunter Jul 24 '17 at 11:58

It is postulated that the trifluroborates are not the transmetallating specis, rather than to be the source of slow hydrolysis to yield boronic acids:

enter image description here

(source, slide 41; citing Molander and Biolatto, B. in J. Org. Chem., 2003, 68, 4302-4314)

which then enter the catalytic cycle:

enter image description here

(preview in Kurti / Czako, page 448 bottom)

Organic Reactions (vide infra) explicitly states that complete hydrolysis of the trifluoroborates is necessary to allow successful transmetallation.

In addition, the fluoride anion is said to interact in the following way with the palladium catalyst:

enter image description here


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    $\begingroup$ Thanks, but I had already found these mechanisms. I'm wondering more precisely about the mechanisms that don't give the desired product and the factors influencing them. $\endgroup$ – Bob Tremblay Jul 23 '17 at 16:12
  • $\begingroup$ Oh. Sorry, I misunderstood "byproduct" as "what is naturally formed beside the product of normal coupling" rather than "product(s) obtained if the intended coupling reaction fails". Let us see suggestions by others. $\endgroup$ – Buttonwood Jul 23 '17 at 16:18
  • $\begingroup$ I clarified the question. Thanks anyways, this is an excellent summary of the general mechanism with sources. $\endgroup$ – Bob Tremblay Jul 23 '17 at 17:57

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