Novel route -> P2P

[pHarmacist]

Didn't want to post this on the "stimulants" becouse this ketone isn't only used in the amphetamine synth..
 
I never heard of using oxiranes (with Gringard reagent) for the preparation of P2P. I don't know if the route is novel, I searched rhodium.ws and hive, no results, but I could be wrong. I hate the fact that I can't post the complete mechanism (I wrote it on paper). But I can describe in words and the little applet drawing below. Actually a Gringard reagent can be prepared from bromobenzene and Mg-tunings. This is then reacted with the oxirane (look below), the intermediate is protonated to give phenyl-2-propanol (don't want to show up in the applet the alcohol is oxidized with PCC or KMnO4 to give the desired ketone.

This is actually a Gringard at it's best, mechanisticly speaking we got a nucleophile attack from the Gringard  reagent on the primary (1*) carbon of the oxirane, this additionaly gives us the secondary (2*) alcohol, the alcohol is then oxidized to the ketone. enjoy:

Molecule:

reaction ("Br[Mg]c1ccccc1.CC1CO1>CC(O)Cc1ccccc1>CC(=O)Cc1ccccc1")



Many thanks to Organikum for helping me out with the Java-applet...

Greetings: Siegfried, Organikum
pHarmacist

[Rhodium]

I have had the outline posted on my page for quite some time -

https://www.thevespiary.org/rhodium/Rhodium/chemistry/p2pol.html

- but I haven't gotten around making a real writeup on it.

[pHarmacist]

Ah ok.. I searched for "oxirane" on your page with no results... what now? By the way, this method is amazing, elegant, clean, why lack of popularity, anyone?
pHarmacist

[Rhodium]

Most people at this board couldn't get a grignard reaction going if their life depended on it. They would need to learn to pay attention to using pure reactants, anhydrous solvents and a controlled laboratory environment.

[El_Zorro]

So what about in TSII, when the guy said he didn't use a N₂, and he said all he did to dry his ether was run it through Na₂SO₄, and he did fine. 

That always made me wonder whether or not he was telling the truth.
Who is that masked man?

[Rhodium]

It is not hard to get a grignard going if you know what you are doing. I have never used inert gas, and how much you need to dry the ether depends on how reactive your substrate is.

[Bwiti]

"They would need to learn to pay attention to using pure reactants, anhydrous solvents"

  I learned the hard way; Listen to what Rhodium says, and don't cut any corners.
Love my country, fear my government.

[pHarmacist]

just put some elemental Na in your ether and put it all in freezer it will keep it dry... As far as N2 atmosphere goes, it's not a must, just take a bent glas-pipe, throw in piece of cotton now some CuSO4 (anhydros) then some more cotton over it (like a sandwich) and connect it to the reflux condenser. it will keep the Gringard alive
pHarmacist

[pHarmacist]

Actually one can instead of "original" Gringard use Li-benzene, Li-benzene could be prepared from bromobenzene and Li, product is more reactive than Gringard reagent, mechanism is the same...
pHarmacist

[Organikum]

Rhodium wrote:

Most people at this board couldn't get a grignard reaction going if their life depended on it

This is the same as with the BIRCH I assume?

It´s on the bromobenzene I think. Schedule 1 precursor like P2P. A real and easy OTC way to bromobenzene might make also this popular when pills and anhydrous ammonium are out of reach.

Looking at the ghetto-stylish but in reality highly sophisticated "pill-cures", I cannot say there is something impossible for lovers of strong stimulanzia.  

ORGY

~ Love is the law, love under will. ~

[Rhodium]

Mg and Li are definitely not interchangeable!

[Organikum]

Mg and Li are definitely not interchangeable!

no doubt, thats right.
I wanted to express the opinion that some years ago no chemist would have believed if told that farmerboys perform a Birch-like reaction. Many won´t believe it nowadays either.

I don´t hope the reaction gets popular as it is risky for health and a catastrophe for the enviroment if done in the bushes by many.

no offense intended
ORGY

~ Love is the law, love under will. ~

[pHarmacist]

Rhodium:

Of course, you can't make a Gringard with Li, but this is compleatly possible:

Ar-Br + 2Li ---Et2O--> Ar-Li + LiBr


Ar-Li can then preform a nucleophillic attac on the primary carbon of the oxirane just like the Gringard did... That was my point...

pHarmacist

[Rhodium]

pHarmacist: What I meant was that alkyllithiums are less chemically selective, and that you cannot automatically use a R-Li when a synthesis calls for R-MgX (there are more added dangers too, but that wasn't my objective).

Organikum: As long as you aren't breathing/touching the ammonia, the birch reaction is extremely simple. You just have a container of ammonia, add an alkali metal "plop, plop, fizz", then add your aromatic "plop, plop, fizz", let the solvent evaporate and you have your product. No big deal. But a grignard reaction is comaratively involved.

[terbium]

But a grignard reaction is comaratively involved.
But a lot of near illiterate ghetto cooks in the US were using Grignard reagent in the 70's and 80's for the synthesiis of PCP. It really used to amaze me that these people could learn to perform a synthesis that involved cyanide and a Grignard reagent.
Baseline Does Not Exist.

[Rhodium]

Maybe morons were smarter 25 years ago?  

[goiterjoe]

ahhh, the wonders of science.  Try to make a reaction idiot-proof, and we will breed a better idiot. 
All paths are the same: they lead nowhere

[pHarmacist]

terbium: good point... true...
[pH]armacist - Elite Killing Technique

[Rhodium]

By the way, would styrene oxide (non-suspicious bulk plastics monomer) and OTC MeMgI also make P2Pol,  or would it be the wrong isomer?

[pHarmacist]

Rhodium, unfortunately, that would give phenyl-ethyl-ketone, as the nucleophillic attack takes place on the primary carbon...

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