why propargyl bromide don't proceed sonogashira cross-coupling reaction with aryl iodide, I tried more than one with different procedures but still no reaction?
I think because there is competitive reaction happened both aryl iodide (sp2-X) and propargyl bromide (sp3-x) with palladium like oxidative addition that is firts step in Sonogashira coupling. if you look at again the model compounds of Sonogashira coupling, there is no propargyl bromide reacted with sp2 by this is. I suggest, propargyl bromide is reacted with other that you want to do again and afterthat, modified propargyl is reacted with aryl iodide by Sonogashira coupling as you plan beforehand. I hope this helps you to solve problem.
https://www.organic-chemistry.org/namedreactions/sonogashira-coupling.shtm
dear Ade Danova, thanks for your answer, I already react propargyl bromide and then do Sonogashira coupling. I want to Know why the reaction does not occur on TLC and the mechanism?
I think one the main reason is that base (like NEt3) used in coupling reaction gives SN2 substitution reaction with propargyl bromide. Thus, bromide anion is eliminated. This competitive reaction prevents the abstracting of proton of alkyne Therefore, copper ion could not connect to alkyne unit. Even if palladium is oxidatively added to aryl iodide, because of above reason the coupling reaction could not complete.
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