[Faris]

Hi Folks,

I have a bit of a problem - I am trying to conduct a peptide bond formation according to the attached image.

My initial thought is to use Hunigs base but I am looking to get the best yield of the product shown. Clearly the L-Valineamide is a di-amine so is there any way to prevent major involvement from the amine at the 2 position ?

Thanks for any help,

Faris

[discodermolide]

You do not have a di-amine. One of the nitrogens is an amide nitrogen, making it less basic than the primary amine. I would not anticipate problems with selectivity here.

[clarkstill]

As disco said, the amide shouldn't interfere with the coupling.  If anything, I'd be slightly more worried about the benzopyrazole nitrogen, but it'll probably be fine.

[Faris]

Thanks Folks - boy am I red in the face! yes, it is an amide nitrogen...more sleep, less late night TV.

Anyways,  any comments on the factors that might affect the % yield of this type of reaction.

Thanks,

Faris