March 29, 2024, 10:26:42 AM
Forum Rules: Read This Before Posting


Topic: Aminolysis from Lactone Rings Using Aluminum based reagents  (Read 4224 times)

0 Members and 1 Guest are viewing this topic.

Offline meaningfulgibberish

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
I've been running this reaction for a couple months now. I take N,O-dimethylhydroxylamine salt, add to it either DIBAL or Trimethylaluminum, then add that solution to a solution of a lactone. Work-up consist of quenching any small amount of DIBAL left, acidification to pH 3-4, then overnight stir in Potassium Sodium Tartrate. Previous grad student would typically get anywhere from 30%-40%. I'm at best getting 20%.

Does anyone have any experiences with these reactions? What are some things I could do to improve yield? I know synthesis can be frustrating but this is beginning to be ridiculous.

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: Aminolysis from Lactone Rings Using Aluminum based reagents
« Reply #1 on: July 23, 2015, 03:35:36 PM »
What is the rest of the material? Starting material or what?
Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline meaningfulgibberish

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Re: Aminolysis from Lactone Rings Using Aluminum based reagents
« Reply #2 on: July 24, 2015, 09:36:10 AM »
At times I'll get a small amount of starting material back, but the mass balance wouldn't make sense if it was a conversion problem. I'm not getting enough starting material back to say that it is a conversion problem. My other guess is that my product may still be stuck on the aluminum. It would explain the drop in yield when I'm using tartrate in my work-up. But then if that's the case, why is it still on there?

Offline discodermolide

  • Chemist
  • Sr. Member
  • *
  • Posts: 5038
  • Mole Snacks: +405/-70
  • Gender: Male
    • My research history
Re: Aminolysis from Lactone Rings Using Aluminum based reagents
« Reply #3 on: July 24, 2015, 10:46:12 AM »
Try using acetic acid quenches. But be careful, keep it controlled. The Rochelle salt may not be enough to remove all the Al, I have had better results, in different systems, with acetic acid.

Development Chemists do it on Scale, Research Chemists just do it!
My Research History

Offline meaningfulgibberish

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Re: Aminolysis from Lactone Rings Using Aluminum based reagents
« Reply #4 on: July 24, 2015, 03:48:23 PM »
I'll give it a shot. Thanks!

Offline Dan

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 4716
  • Mole Snacks: +469/-72
  • Gender: Male
  • Organic Chemist
    • My research
Re: Aminolysis from Lactone Rings Using Aluminum based reagents
« Reply #5 on: July 25, 2015, 09:40:07 AM »
What to you have planned for the Weinreb amide product? I ask because morpholine might be a better choice, see:

http://www.sciencedirect.com/science/article/pii/S0040402014003792
My research: Google Scholar and Researchgate

Offline meaningfulgibberish

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Re: Aminolysis from Lactone Rings Using Aluminum based reagents
« Reply #6 on: July 30, 2015, 02:31:51 PM »
What to you have planned for the Weinreb amide product? I ask because morpholine might be a better choice, see:

http://www.sciencedirect.com/science/article/pii/S0040402014003792

This looks great! I use the weinreb amide to make a ketone. The grignard addition works fine, but this looks like a much better alternative. Thank you!

Sponsored Links