In a single pot reaction , two processes are occuring simultaneously i.e. homocoupling and oxidative cross coupling reaction . How could we prevent one process selectively i.e; homocoupling? .
Boronic acid homocoupling is promoted by oxygen. If you want to prevent homocoupling, deoxygenating the solvent and then carrying out the reaction in an inert atmosphere should do the trick.
This helped me in avoiding homocoupling of boronic acids in this article: 10.1016/j.jorganchem.2018.06.016
See this article for more information about Pd catalyzed homocoupling of boronic acid: 10.1021/ja0569959
The homocoupling reaction proceeds at ambient temperature in air without any additives such as base or oxidant. This method tolerates various substituents on the arylboronic acids such as halogens, carbonyls, and a nitro group.
The pre-heating of metal catalyst, base, solvent and other coupling partener except boron neucleophile is an usual proactive to avoid the homocoupling of boron neucleophile in cross-coupling reactions. Finally after heating the contents for at least 10 min. at about 60-80 oC the boron neucleophile (usually arylboronic acid) can be added.
Thank You very much Sir, for Your valuable suggestion. I think it will definitely help to us. Thanks again.
the homocoupling is possible when the same reagent has an electrophile and nucleophile in the same molecule. we may deactivate one centre by suitable substitution depnding on the cross coupling reagent is eithe electrophile or nucleophile provided the substituent is inert to your purpose or can be removed at the nd.
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