April 29, 2024, 11:31:34 PM
Forum Rules: Read This Before Posting


« previous next »
Pages: [1]   Go Down

Topic: Tough asymmetric synthesis  (Read 2752 times)

0 Members and 1 Guest are viewing this topic.

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Tough asymmetric synthesis
« on: January 05, 2016, 11:06:51 AM »
How to achieve the following transformation:

My attempt is attached. Will it work?
Logged

Offline TheUnassuming

  • Chemist
  • Full Member
  • *
  • Posts: 461
  • Mole Snacks: +48/-1
Re: Tough asymmetric synthesis
« Reply #1 on: January 05, 2016, 03:41:31 PM »
The first thing that catches my eye is the different cyclization possibilities for the opening of the epoxide.  It could go the 6-exo sort of cyclization you show, but also 5-endo to form the furan derivative.
Logged
When in doubt, avoid the Stille coupling.

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: Tough asymmetric synthesis
« Reply #2 on: January 05, 2016, 03:53:47 PM »
Yeah, that would have low yield. Any alternative approach?
Logged

Offline Babcock_Hall

  • Chemist
  • Sr. Member
  • *
  • Posts: 5614
  • Mole Snacks: +322/-22
Re: Tough asymmetric synthesis
« Reply #3 on: January 05, 2016, 04:18:56 PM »
Will an epoxide survive in the presence of ammonia?
Logged

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: Tough asymmetric synthesis
« Reply #4 on: January 05, 2016, 05:26:29 PM »
Guess not.
Logged

Offline TheUnassuming

  • Chemist
  • Full Member
  • *
  • Posts: 461
  • Mole Snacks: +48/-1
Re: Tough asymmetric synthesis
« Reply #5 on: January 05, 2016, 05:30:19 PM »
Not sure about the work around.  Basic vs lewis acidic routes might give you different selectivity profiles, you'll have to check the literature on that one.   

I didn't see it, but babcock_hall made a good catch.  Can probably get away with just switching the order though.
Logged
When in doubt, avoid the Stille coupling.

Offline Rutherford

  • Sr. Member
  • *****
  • Posts: 1868
  • Mole Snacks: +60/-29
  • Gender: Male
Re: Tough asymmetric synthesis
« Reply #6 on: January 05, 2016, 05:31:59 PM »
Okay, 1st Birch, then Sharpless then protection of -OH with TBS.
Logged

Offline TheUnassuming

  • Chemist
  • Full Member
  • *
  • Posts: 461
  • Mole Snacks: +48/-1
Re: Tough asymmetric synthesis
« Reply #7 on: January 05, 2016, 05:37:31 PM »
Seems reasonable to me.

You also might have troubles getting selectivity for the dioxolane vs TBS when you deprotect at the end.
Logged
When in doubt, avoid the Stille coupling.
Pages: [1]   Go Up
« previous next »
Sponsored Links