[veselin]

I am using DCC for coupling N-Boc-glycine and 2-iodo-aniline (THF,RT, over night) - it works with aniline and N-Boc-glycine.

In GC/MS (from reaction mixture) I don't see product (there is no peak in chromatogram), dominant iz DCU (mass 224, 45 %). There is something with mass 200 (10%) and I don't know what is it. There is sth mass 125 (12 %) and 2-Iodo-aniline (32%). Does anybody know what is happening and why I don't see product?

I did this reaction with N-Boc-glycine and aniline (yeald over 50%) and I saw product in GC/MS (also I saw sth with mass 200 and 125).

Thanks

[opsomath]

Sounds like the iodine kills the nucleophilicity of the aniline. 2-iodoaniline has a pKa of 2.6 while aniline is 4.6 - that is, aniline is 100 times more basic. This is some combination of the steric bulk of the iodine, the iodine serving as a through-space electron acceptor (halogen bond acceptor), and the iodine being an electron withdrawing group. (It looks like a bit more than half of it is through-space effects, since pKa of 4-iodoaniline is 3.

So, iodoaniline isn't as good a nucleophile. Darn. Try adding DMAP.

[veselin]

I added DMAP (in aniline and iodo-aniline case), but I have forgotten to mention it

I ll try some other way to obtain that amide

Thank you

[Babcock_Hall]

Could the reaction just be sluggish?  How much time are you giving it?

[MOTOBALL]

Isn't the formation of DCU from DCC evidence that the reaction has proceeded (or has it been formed from adventitious water) ??