[Mpatas]

Hello,

I would like to ask you about a reaction that i tried recently. I wanted to deprotonate by using LDA the methyl group of my compound which is 6-methyl-6'-(trifluoromethyl)-2,2'-bipyridine. I followed a literature procedure which is about the deprotonation of 6-methyl-2,2'-bipyridine. My question is do you believe that the acidity of the protons of the methyl group differ between the -CF3 substituted and the 6-methyl-2,2'-bipyridine? As far as i know CF3 acts like a deactivating group. This will lead to lower aciditiy?

[TheUnassuming]

In theory the CF3 group should make it easier to deprotonate. 
What exactly did you try/do and what happened?

[Mpatas]

I made LDA in situ to deprotonate 6-methyl-6'-(trifluoromethyl)-2,2'-bipyridine and then i added my phosphine and stirr overnight gave no conversion. After that i reflux it for 6 days and i had 5 % conversion.

[TheUnassuming]

One thing you could try is do the deprotonation, but instead of adding the phosphine, quench with D2O.  Then work up and analyze to see if you now have a D at that position.  This way at least you will know if your problem comes from incomplete deprotonation or if there is some issue with the electrophile/attack.

[orgopete]

Without looking up any values, I don't think the CF3 group had any effect on the deprotonation. The deprotonation should be instantaneous. Refluxing may result in decomposition of the pyridyanion. I too suggest checking your LDA/deprotonation step with a deuterium quench or add a better electrophile than a phosphine.

[Mpatas]

Thanks for your suggestions but i would like to mention a few things that i already tried.

The deprotonation of 6-methyl-2,2'-bipyridine and the addition of Alkylphosphine chloridie works perfectly fine. The reaction completed overnight. However, when try to do the same for 6-methyl-6'-(trifluoromethyl)-2,2'-bipyridine the reaction is extremely slow as i mentioned before. Taking into account this i am sure that the CF3 resulits in slow reaction that i cannot really explain.