A question about Grignard reagent and Kumada coupling

Yes, but methane is not a big problem, if the fume’s ventilation is “on”.
The problem is the unreacted magnesium, which is in micro/nanosuspension form and activated by the remaining traces of the preliminary added, iodine crystal that will form magnesium hydride with the “active” hydrogen; which by its turn, will react with another “active” hydrogen and will finally lead to the formation of gaseous hydrogen.
Of course, this problem can be avoided by purchasing pre-prepared methylmagnesium bromide from suppliers.

The Grignard will attack the carbamate-carbonyl?

You could try a Stille-coupling where you use a tin-derivative instead of a boronic acid. I have done this reaction and you can use PdCl2 as catalyst, I think this is because the tin-derivative reduces it in situ to Pd(0).

https://en.wikipedia.org/wiki/Stille_reaction

Thnx alot

The Kumada coupling forms a C-C bond from a grignard and a molecule containing a C-X bond (X=I,Br,Cl; normally aryl-X or alkenyl-X) - I'm not sure exactly how you hope to use it here.

You can use the halothiophene and grignard, just use more of the grignard when the first eq. will be consumed by the amidic proton.

Thnx
I can certainly propose this in my thesis as I have no time more left to work in the lab.

But even being a halothiophene derivative, the amide hydrogen will immediately deactivate the Grignard reagent.

Alkylmagnesium halide will give trialkylcarbinol + benzyl alcohol + (N-)alkyl 3-thiophenamide.
But usually, low yields are obtained by using excess of Grignard reagents when active (acidic) hydrogens are present; in addition to the vigorous (and dangerous) formation of hydrogen gas (windows must be open during the reaction, in order to avoid any formation of 2/1 explosive mixture).

Ok, thank you very much

Is it because the amide is acidic and will protonate the Grignard reagent?

If, for example, methylmagnesiumbromide reacts with a acidic hydrogen, does this not form methane, not hydrogen?

The stannane is cheap;

https://www.sigmaaldrich.com/catalog/search?term=Tributylstannylthiophene&interface=All&N=0&mode=match%20partialmax&lang=en&region=SE&focus=product

Yes, Grignards are strong bases.