August 10, 2022, 06:51:28 AM
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Topic: S- vs. O-alkylation using sodium sulfinates  (Read 3146 times)

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Offline rolnor

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Re: S- vs. O-alkylation using sodium sulfina
« Reply #30 on: July 10, 2022, 02:18:04 AM »
You are very dedicated, good. Still it would be nice to se a chromatogram, preferably a LC-MS. You dont learn so much from this NMR-study, its mostly confusing.
Yes, why do you see the iodide? Thats key, it should be consumed. If you used the sulfide as nuchleophile and then oxidised to sulphone you would get fast and more clear result I think. You could even do this one-pot.

Offline Babcock_Hall

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Re: S- vs. O-alkylation using sodium sulfinates
« Reply #31 on: July 10, 2022, 09:58:42 AM »
The TLC results and the P-31 NMR results were consistent with each other regarding both leaving groups.  With P-31 one might be able to learn what the side-product is when I used toluenesulfonate as the leaving group.  I am consulting with someone with much greater expertise in P-31 NMR than I have, although MS could also identify it.

The sulfonyl fluoride reaction followed by a Horner reaction can be done in one pot, but I am not sure that I want to go that route.  Do you mean sulfide, disulfide, or thiol?
« Last Edit: July 10, 2022, 10:22:59 AM by Babcock_Hall »

Offline rolnor

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Re: S- vs. O-alkylation using sodium sulfinates
« Reply #32 on: July 10, 2022, 01:33:25 PM »
If you alkylate a sulfide-Na salt  with the tosylate or iodide you get the sulfide, then oxidize this one-pot with Oxone to the desired sulphone. What you need is mercapto ethanol sodium salt I think?
Its probably so, that you dont get the product you want now, just as your NMR shows, but you dont know why, if you run LC-MS you can maybe see what goes wrong.
« Last Edit: July 10, 2022, 02:06:53 PM by rolnor »

Offline Babcock_Hall

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Re: S- vs. O-alkylation using sodium sulfinates
« Reply #33 on: July 11, 2022, 04:19:15 PM »
We performed the reaction between 3-mercapto-1-propanol and diethyl phosphonomethyltoluenesulfonate at least twice, once with potassium carbonate as the base and IIRC once with cesium carbonate as the base.  Although the yield has been variable in our hands, it is a satisfactory reaction overall.  The oxidation to the sulfone went smoothly.  It would make sense to use 2-mercaptoethanol in a similar reaction; it is inexpensive and not that volatile.  However, the corresponding sulfonyl phosphonate is not presently one of our targets.  The high cost of many of the sodium sulfinates makes this route (EDT, meaning sulfinate as the nucleophile) less attractive to me than it was before, but I already have sodium cyclopropanesulfinate in hand.
« Last Edit: July 11, 2022, 07:09:00 PM by Babcock_Hall »

Offline rolnor

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Re: S- vs. O-alkylation using sodium sulfinates
« Reply #34 on: July 11, 2022, 05:25:50 PM »
Excellent! I move my fingers like Mr Burns in "Simpsons".

Offline Babcock_Hall

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Re: S- vs. O-alkylation using sodium sulfinates
« Reply #35 on: July 12, 2022, 09:52:36 AM »
A year ago we alkylated benzyl mercaptan and then oxidized the product sulfide.  This spring we alkylated 2-thiopyridine and then oxidized the product.  I suspect that these reactions are slower owing to steric problems associated with the quaternary phosphorus atom, but they are otherwise OK.

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