May 17, 2022, 09:23:50 AM
Forum Rules: Read This Before Posting


Topic: Tandem reaction : conditions?  (Read 10326 times)

0 Members and 1 Guest are viewing this topic.

Offline faust

  • Regular Member
  • ***
  • Posts: 72
  • Mole Snacks: +3/-13
  • I'm a mole!
Tandem reaction : conditions?
« on: October 16, 2005, 10:10:49 AM »
Hello

I'm looking for condition to do a tandem reaction for my first step.

i think a good way is the following : addition of PhS(e)Cl by michael addition than capture of the enolate by C akylation on bromopentene. Then oxydation and elimination of PhS(e)O2

But after two hours on Scifinder, I can't find conditions! (solvent, time of reaction, base?, equivalent)

Do you have any references with experimental conditions? Or any other idea for my synthesis of acid?

Thank you


Offline Mitch

  • General Chemist
  • Administrator
  • Sr. Member
  • *
  • Posts: 5297
  • Mole Snacks: +376/-3
  • Gender: Male
  • "I bring you peace." -Mr. Burns
    • Chemistry Blog
Re:Tandem reaction : conditions?
« Reply #1 on: October 16, 2005, 12:13:50 PM »
Do you have access to an ozonolysis machine, I noticed your synthesis uses ozone?
Most Common Suggestions I Make on the Forums.
1. Start by writing a balanced chemical equation.
2. Don't confuse thermodynamic stability with chemical reactivity.
3. Forum Supports LaTex

Offline faust

  • Regular Member
  • ***
  • Posts: 72
  • Mole Snacks: +3/-13
  • I'm a mole!
Re:Tandem reaction : conditions?
« Reply #2 on: October 16, 2005, 12:40:42 PM »
yes I have access, that not a problem. Only the first step is a problem for me...

Offline movies

  • Organic Minion
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 1973
  • Mole Snacks: +222/-20
  • Gender: Male
  • Better living through chemistry!
Re:Tandem reaction : conditions?
« Reply #3 on: October 16, 2005, 01:44:27 PM »
Check out the Bayliss-Hillman reaction.

Also, ozone might chew up the double bond on the other side of your molecule.  I think other procedures like OsO4/NaIO4 are usually more selective and mild.

Offline faust

  • Regular Member
  • ***
  • Posts: 72
  • Mole Snacks: +3/-13
  • I'm a mole!
Re:Tandem reaction : conditions?
« Reply #4 on: October 16, 2005, 01:48:00 PM »
yes I know the bayliss hilmann... but it's trapped with an aldehyde...

I have already tryed ozonolyse with this molecule and the "michael" double bond isn't converted into ozonide

Offline movies

  • Organic Minion
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 1973
  • Mole Snacks: +222/-20
  • Gender: Male
  • Better living through chemistry!
Re:Tandem reaction : conditions?
« Reply #5 on: October 16, 2005, 05:23:20 PM »
It doesn't have to be an aldehyde in the Bayliss-Hillman reaction.  You might be able to use an alkyl bromide as well.

Offline Mitch

  • General Chemist
  • Administrator
  • Sr. Member
  • *
  • Posts: 5297
  • Mole Snacks: +376/-3
  • Gender: Male
  • "I bring you peace." -Mr. Burns
    • Chemistry Blog
Re:Tandem reaction : conditions?
« Reply #6 on: October 16, 2005, 06:13:56 PM »
The double bond in the ring wouldn't get chewed up first by ozone, so you could selectively perform ozonolysis.
Most Common Suggestions I Make on the Forums.
1. Start by writing a balanced chemical equation.
2. Don't confuse thermodynamic stability with chemical reactivity.
3. Forum Supports LaTex

Offline movies

  • Organic Minion
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 1973
  • Mole Snacks: +222/-20
  • Gender: Male
  • Better living through chemistry!
Re:Tandem reaction : conditions?
« Reply #7 on: October 16, 2005, 06:57:16 PM »
Yeah, I figured that you might have a shot since it is electron deficient, but I wasn't sure how good the selectivity was in reality.

Offline HP

  • Chemist
  • Full Member
  • *
  • Posts: 350
  • Mole Snacks: +33/-5
  • Gender: Male
Re:Tandem reaction : conditions?
« Reply #8 on: October 17, 2005, 01:36:59 PM »
What about if you start your synthesis from tetronic acid  to brominate its OH group by Appel reaction with CBr4/PPh3 and after that Grignard with  penteneMgBr.
xpp

Offline faust

  • Regular Member
  • ***
  • Posts: 72
  • Mole Snacks: +3/-13
  • I'm a mole!
Re:Tandem reaction : conditions?
« Reply #9 on: October 17, 2005, 03:13:50 PM »
Sorry I didn't catch your reaction...

I start from tetronic acid (the same as my first molecule but with a OH in beta of the ketone) --> it become a Br and then I don't catch the reaction with penteneMgBr... It will do an addition 1-2 on my ketone...

Offline HP

  • Chemist
  • Full Member
  • *
  • Posts: 350
  • Mole Snacks: +33/-5
  • Gender: Male
Re:Tandem reaction : conditions?
« Reply #10 on: October 18, 2005, 11:28:09 AM »
You are probably right about this side reaction...Then i suggest you to obtain organozink or cadmium derivate of your halopentene which may be much selective for your C-C forming  ???
Really complicated synthesis :) I'll think for anotrher rote...
xpp

Offline faust

  • Regular Member
  • ***
  • Posts: 72
  • Mole Snacks: +3/-13
  • I'm a mole!
Re:Tandem reaction : conditions?
« Reply #11 on: October 18, 2005, 01:15:00 PM »
i can do an organozincic, but i'll do an addition 1.4 and be in beta of the carbonyle but i want to functionnalize the alpha position...

Offline HP

  • Chemist
  • Full Member
  • *
  • Posts: 350
  • Mole Snacks: +33/-5
  • Gender: Male
Re:Tandem reaction : conditions?
« Reply #12 on: October 18, 2005, 02:41:57 PM »
Oh, now  i see your broblem  :o really hard one ..Think about how to obtain alfa-halo derivate?
xpp

Offline faust

  • Regular Member
  • ***
  • Posts: 72
  • Mole Snacks: +3/-13
  • I'm a mole!
Re:Tandem reaction : conditions?
« Reply #13 on: October 19, 2005, 01:05:10 AM »
In fact I have seen a publication with the variant of Bayliss Hilmann.

They use Ph-Se-Li instead of DABCO. and they do an addition of an aldehyde... May be I can try to replace the aldehyde by the bromopentene... But I don't know if it is commercial or not (the bromopentene)

Offline HP

  • Chemist
  • Full Member
  • *
  • Posts: 350
  • Mole Snacks: +33/-5
  • Gender: Male
Re:Tandem reaction : conditions?
« Reply #14 on: October 19, 2005, 12:03:03 PM »
Now i think a synthesis start from furan-2(5H)-one which if react addition with B2 to give 3,4-dibrom dihydrofuran-2-one. In this compound you have 2 Br athom close to different group: alfa and beta-position the carbonyl(CO) one.Then i suppose the alfa-brom will be much reactive with for example bromcadmium pentene and after C-C formin on alfa-position you siply have elimination with alcoholic KOH to eliminate HBr and may be to obtain desired product...I dont know try to imagine that synth :)
xpp

Sponsored Links