One thing you have to purge the water with argon atleast half an hour before putting the reaction. You can use THF + water as solvent. Base is K2CO3 but it should activated before putting the reaction. Low yield mainly because of homocoupled product. Temperature is about 75degree . Using this condition repeat the reaction one more time. Everything add to to the reaction with out any delay.

Hello Danish,

I've been suffering from the same bad results with the Suzuki-Miyaura coupling.

It seems like practically every reaction has its need for tunning.

However, I've seen somewhat good results with:

Heating: think of using microwave irradiation

solvent: THF/Water 4:1

Toluene/Water 2:1

DMF (no water)

Temperature: I believe you're using the correct range of temperatures...but I've seen some reactions performed well at 120°C...you could try that.

Catalyst: Tetrakis(triphenylphospine) Palladium is a very good choice. If yo don't have it, you can prepare it in situ with Pd(OAc)2 and PPh3

Base: you could try cesium carbonate or a importan excess of base...maybe more than 3-4 equiv.

I've seen this conditions work in several cases.

Additionally, maybe you should consider trying (it that's your case) direct (hetero)arylation reactions.

Hope any of these suggestions helps.

Wish you success and keep trying.

Preethanuj Preethalayam Thank you for your answer

I first mix the reactants in solvent for 5 min and then i mix the base with water and do addition of base. After that i purge my reaction bottle again with nitrogen and then i add catalysts. I've tried 80 degree for 2 hours but i observed no conversion. then i left the reaction mixture overnight but same problem. The only thing which i haven't used is the THF. I would try this.

Any more suggestions?

Oscar González-Antonio

Thank you for your answer. My compound is Ester and i am afraid if i increase the temperature i might start to break down at this temperature. I have tried max 100 degree for 2 hours. You have provided me with different set of reaction conditions and i would try them one by one.

Thank you for your help.

Dear Friends

I can recommend Cs2CO3 as efficient base than Na or K.

If you are using water as a solvent under inert conditions it is preferable to use seal tube in order to increase the selectivity of desired product.

Tetrakis as catalyst is most recommended according to literature.

I can recommend Cs2CO3 as efficient base with inert without moisure dmf 110 degree with nitrogen shilled tube and m

Hi Danish,

Regarding to the S-M cross coupling, well... the reaction contidions, workup and purification are very relative to the substrate. The catalyst, base, solvent system can vary A LOT depending on the substrates.

I highly reccomend you that you look carefully in bibliography the most similar example to your system to get the best result possible.

All the best!

Hi Danish,

You can use some other combination of Ligand and catalyst like what i have tried was Pd2(dba)3 and P(Cy)3 in 1:2 ratio in Dioxane water mixture (9:1) and K2CO3 or Cs2CO3 as base. You can also use tetrakiss in different solvent like toluene: water or Dioxane: water or THF: water. In some reaction i have seen that people are using Toluene: EtOH: water mixture also. so you can try all these.

Best of Luck....

it is better to continue with palladium only with different reaction time.........or use different solvent combinations like

THF/Water 4:1

Toluene/Water 2:1

DMF (no water)

are u using organic halides with boronic acids or what.

but please check the solubility in given solvent otherwise use the magnetic stirrer to make soluble check the TLC while performing the reaction..

All the best......

Hi Danish,

In my opinion the catalyst used works well for S-M reaction. But the low yields may be due to the substrate scope. We are not aware of your substrate whether highly sensitive or mild reactive. Based on the reactivity and presence of other sensitive functional groups, you may preferably change the solvent that works good for isolation and the base condition. Also you should have a keen observation over TLC whether starting material is being converting completely and if so in what much time? A better observation at regular intervals of time may gives you likely answer, at what time to stop the reaction and reduce the risk of by-products and side products. If the impurity is due to another reactant say boronic acid, if used in used in excess, you can minimise the problem of purification following acid-base treatment.

several factors are affect the reaction yields:

# Limit the number of transfers. Every time you transfer a component to another container, you lose some of the compound.

# Add more of one reactant. If your reaction is an equilibrium reaction, use a large excess of the cheapest reactant.

# Remove a product as fast as it forms. Removal of product forces the position of equilibrium to the right and increases the yield.

# If your reactants are gases and you have fewer moles of gaseous products, increase the pressure.

# Give the reaction time. If you stop a slow reaction before it has had time to complete, you will have a low yield.

# Add a catalyst. It won't change the yield, but the reaction will be faster. You will be less likely to stop the reaction before it has finished.

2 spots very closer:

The two spots are closed, which is depends upon the nature of the starting materials and products, because of the starting material and product has same polarity, that is the reason your getting two spots are closer. so my suggestion is always you try the TLC with nonpolar solvent like 100% petroleum ether, if not moving the spot than you can increase the polarity PE 90%/EA 10% like this. then you will see the difference.

Base:

Some of them already suggested cesium carbonate, you try this if it is not working you move to another bases like triethylamine, pyridine etc...

Starting materials:

if you using bromobenzene and phenylboronic acid as starting material. after checking the TLC you should warm the plate then you see the TLC to confirm the product because of bromobenzene is evaporated, only the product is remaining the TLC.

Thank you....

You can try the same reaction conditions, but in microwave as source of energy. 100 °C, 100 watts, 15 minutes. and you can extract it with ethyl acetate or dichloromethane as usual