March 29, 2024, 12:51:26 AM
Forum Rules: Read This Before Posting


Topic: CDI (carbonyldiimidazole) usage in peptide synthesis  (Read 6916 times)

0 Members and 1 Guest are viewing this topic.

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: CDI (carbonyldiimidazole) usage in peptide synthesis
« Reply #15 on: February 15, 2014, 11:48:03 AM »
this is what I mean
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: CDI (carbonyldiimidazole) usage in peptide synthesis
« Reply #16 on: February 15, 2014, 11:49:20 AM »
Oh, so the resonance I wrote isn't possible here, but it is in 1,1’-carbonyldipyrrolidine, correct?

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: CDI (carbonyldiimidazole) usage in peptide synthesis
« Reply #17 on: February 15, 2014, 11:50:23 AM »
what is wrong with that?
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: CDI (carbonyldiimidazole) usage in peptide synthesis
« Reply #18 on: February 15, 2014, 11:51:36 AM »
I saw the first time I looked at your post the scheme you uploaded before, but now it's okay.

Offline orgopete

  • Chemist
  • Sr. Member
  • *
  • Posts: 2636
  • Mole Snacks: +213/-71
    • Curved Arrow Press
Re: CDI (carbonyldiimidazole) usage in peptide synthesis
« Reply #19 on: February 16, 2014, 09:15:55 AM »
this is what I mean

While that could be the mechanism, I don't think it is. An imidazolium anion is fairly basic. I think the key is elimination of a neutral imidazole. The mechanism posted by Raderford was virtually correct, except the wrong nitrogen was protonated. If an amino acid protonated the imidazole, it would free the amino group and make neutral imidazole the leaving group. The other option is to write a concerted proton abstraction, but that will put an entropy load on the reaction.
Author of a multi-tiered example based workbook for learning organic chemistry mechanisms.

Sponsored Links