The best C-C coupling of the bromo-aryl having -NO2 group, out of Kumada, Negishi, Stille or Suzuki. The main issue is whether the corresponding grignard reagent, Zn-reagent, Tin-reagent or boronic acid/ester would able to react without affecting -NO2 of bromo-substrate. I have already doubt on Negishi and Kumada.
Best method is coupling of bromo substituted nitrobenzene with appropriate boronic acid derivative in following conditions: solvent: Acetone:water 60:40) Base: sodium carbonate 1 mol% palladium acetate, RT-30 min.
Suzuki works great. The above conditions leave out a ligand. PPh3 should be fine. You'll probably also need some heat and therefore a solvent besides acetone (DMF, THF, Tol/EtOH)
Stille or Suzuki work well here, oxidative addition is facile for nitrobenzene derivatives, even the Ullman type couplings work fine. My preference would depend on the the structure and availability of the other coupling partner. For acid or base sensitive substrates I prefer the Stille coupling, the organostannanes are generally very tractable oils and stable to chromatography; however they are extremely toxic and a little unpleasant smelling.
If your system is fairly robust then the Suzuki coupling works for most substrates. Many broadly orthogonal conditions are published in the literature so there are a lot of options for optimisation, even at room temperature. The boronates are more annoying to synthesise though. If you run into difficulties this is the most likely coupling that you will get to work.
Depending on your substrate, the less common Hiyama coupling with activated organosilanes can also be quite effective; It is less well established but in my opinion offers an excellent balance in being quite easy to synthesise and manipulate, without the toxicity of the organotin reagents. The downsides are reduced commercial availability and less literature precedence.
Best choice will generally be substrate dependent or based on personal preference. CuI can be a helpful co-catalyst in stabilising the oxidative addition product and promoting transmetallation.
The system don't have any acid or base sensitive functionalities, only -NO2 on bromo-aryl substrate.
Go with the cheaper/easier available option then. If you already have either the stannane or boronate then go with that.
I think you can try Gillmann reagent. You wants to keep & save acidic functionality like nitro group.Which is active and then shouldn't be destroyed. Gillmann will work but its less active. So will beneficial, otherwise Suzuki is best choice.
Best C-C coupling for the bromo-substrate having nitro-group one can use Suzuki coupling
- Badges
- Science topic
- Similar topics
- Chemistry
- Organic Chemistry