December 27, 2024, 06:27:34 AM
Forum Rules: Read This Before Posting


« previous next »
Pages: [1]   Go Down

Topic: Retrosynthesis question  (Read 2894 times)

0 Members and 2 Guests are viewing this topic.

Offline spidermclovin

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Retrosynthesis question
« on: November 28, 2018, 09:26:05 AM »
A retrosynthetic question asks for the synthons, real reagents and synthesis from the disconnection attached (shown in red). The alcohol group in this molecule makes grignard reagents unusable. Any ideas?
Logged

Offline sjb

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 3653
  • Mole Snacks: +222/-42
  • Gender: Male
Re: Retrosynthesis question
« Reply #1 on: November 28, 2018, 10:15:46 AM »
What reactions do Grignards undergo?
Logged

Offline Babcock_Hall

  • Chemist
  • Sr. Member
  • *
  • Posts: 5715
  • Mole Snacks: +331/-24
Re: Retrosynthesis question
« Reply #2 on: November 28, 2018, 02:24:44 PM »
What other reactions do you know that form C-C bonds?
Logged

Offline rolnor

  • Chemist
  • Sr. Member
  • *
  • Posts: 2309
  • Mole Snacks: +154/-10
Re: Retrosynthesis question
« Reply #3 on: November 29, 2018, 10:07:08 AM »
This could work, thiophene-chemistry:
Logged

Offline rolnor

  • Chemist
  • Sr. Member
  • *
  • Posts: 2309
  • Mole Snacks: +154/-10
Re: Retrosynthesis question
« Reply #4 on: November 29, 2018, 10:09:26 AM »
Sorry for messy scheme, the cyclohexyl thiophene is lithiated with n-BuLi.
Logged

Offline kriggy

  • Chemist
  • Sr. Member
  • *
  • Posts: 1520
  • Mole Snacks: +136/-16
Re: Retrosynthesis question
« Reply #5 on: November 29, 2018, 03:42:30 PM »
what about conjugated 1,6 addition and then reduction of the ketone and double bonds?
Logged

Offline clarkstill

  • Chemist
  • Full Member
  • *
  • Posts: 477
  • Mole Snacks: +77/-4
Re: Retrosynthesis question
« Reply #6 on: November 30, 2018, 04:03:32 AM »
Quote from: rolnor on November 29, 2018, 10:07:08 AM
This could work, thiophene-chemistry:

I've literally never seen that before but it's neat - thiophene as a masked n-butyl group!

I was thinking along the lines of a Wittig-hydrogenation (attached)...
Logged

Offline rolnor

  • Chemist
  • Sr. Member
  • *
  • Posts: 2309
  • Mole Snacks: +154/-10
Re: Retrosynthesis question
« Reply #7 on: November 30, 2018, 05:41:11 AM »
The Wittig-reagent is very basic and it could be quenched by the OH-group? Perhaps a protection-group?
Logged

Offline wildfyr

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 1777
  • Mole Snacks: +203/-10
Re: Retrosynthesis question
« Reply #8 on: November 30, 2018, 09:46:18 AM »
That thiophene trick is really great!
Logged

Offline rolnor

  • Chemist
  • Sr. Member
  • *
  • Posts: 2309
  • Mole Snacks: +154/-10
Re: Retrosynthesis question
« Reply #9 on: November 30, 2018, 10:59:07 AM »
Thanx wildfyr! :)
Logged

Offline clarkstill

  • Chemist
  • Full Member
  • *
  • Posts: 477
  • Mole Snacks: +77/-4
Re: Retrosynthesis question
« Reply #10 on: November 30, 2018, 11:37:21 AM »
Quote from: rolnor on November 30, 2018, 05:41:11 AM
The Wittig-reagent is very basic and it could be quenched by the OH-group? Perhaps a protection-group?

I don't think it's a problem, people tend to just use 2 eq. of the ylide, e.g. compound 9 here:

https://pubs.acs.org/doi/suppl/10.1021/jo8017704


... but I concede the thiophene method looks much more fun.
Logged
Pages: [1]   Go Up
« previous next »
Sponsored Links