Hi,

I recently found a patent about base-catalysed hydroamination of styrenes. High yield are reported on some substrates.

Exemples :

Allylbenzene : Methylamine (2:1) in THF, Base = BuLi 20 mol% , 50°C, Yield = 60% methamphetamine

Prop-1-enylbenzene : Diethylamine (0,5 : 0,3) in THF, Base = Na2Np (0,05), RT, Yield = 85% diethylamphetamine [2]

Prop-1-enylbenzene : Morpholine (1:1) in THF, Base = BuLi 10 mol%, Yield = 69% [3]

[1]See Attached patent

[2]The Reaction of Amines
with Conjugated Dienes in the
Presence of Alkali Naphthalenide.
A New Synthesis of Geranyl Acetate
T. Fujita, K. Suga and S. Watanabe

[3]Base-catalyzed amination of olefins: an example of an
environmentally friendly synthesis of amines
Matthias Beller *, C. Breindl

0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0

So I decided to do a trail on safrole with PrNH2 as the base:

Materials:

250 ml RBF is fitted with a thermometer and a reflux condeser. The THF is previously dried over LiAlH4 and the flask is dried in an oven and flushed with nitrogen before use. All the reaction was performed under nitrogen.

Reagents :

All the reagent (except safrole) are purum or puriss and ordered from sigma-aldric or Acros chemicals. Safrole is distilled from sassafras oil.

1.315g (10.3 mmol) Naphtalene is dissolved in 50 ml THF [note 1]. 0.4725g (20.6 mmol) sodium is cutted into small pieces and added to the naphtalene solution. This latter is magnetically stirred. 10 min later the suspension is dark green, it's not possible to see the sodium chips. The green suspension is let stirred at RT for 2h. 3.6g (60.9 mmol) Propylamine is rapidely added. 5 min later, the green colour disapear and the temperature rise up. Next, a solution of 2.4g (40.0 mmol) propylamine and 10g (62.7 mmol) is added dropwise over the course of 1h. The reaction mixture is let stirred under nitrogen atmosphere for 2 days.

The yellow solution is quenched with 3ml MeOH, THF is rotavapored off and the residue is treated with 10% HCl until pH is strongly acidic. The solution is extracted with 2x50 ml Toluene, and after evaporation of the solvent under vacuum it last 8.1g of yellow/orange oil containing (probably) isosafrole and naphtalene. The aqueous phase is basified with 2M NaOH and extracted with 3x toluene. The propylamine freebase is removed (along with 3/4 of the toluene)with a rotavap and the amine [note 2]is neutralised with 1M oxalic acid in iPrOH. Nothing crystallised. The flask is put in the fridge but there is no crystal at all.

I'll try to form the HCl salt next time.

[note 1] Less THF is used in the patent. Using less THF will increase the formation speed of the sodium naphtalide.
[note 2] The amine solution in toluene has a green colour.

General notes :

- Yield will be poor because most of the safrole has been recovered.
- One of my teammate tried this reaction on safrole with N-Methylbenzylamine and all the (iso)safrole was recovered. Yield is less than 3 %.

I hope you appreciated my work and I'm looking foward to seeing your comments and tips to improve this interesting one-step amination.

Dr.Methoxy

How strong of a base is nescessary? it would be practical and indeed useful if one didn't have to use organolithium bases nescessitating shlenk techniques.

Trust a trailertrash redneck meth cook with that sort of reaction? hehe, that would be a way to get that particular demographic to autodarwinate in short order.

And the DEA thought the red phos reduction was responsible for a fuck-ton of fires....

i like the term "autodarwinate" should be placed in the urban dictionary
clever play on words QD!!!

probably LDA would have a sufficient pkb what so you think???

i like the term "autodarwinate" should be placed in the urban dictionary
clever play on words QD!!!

Actually its Tsathoggua who wrote that jonny boy .

Wilhelm Schlenk invented the schlenk flask:

h**ps://secure.wikimedia.org/wikipedia/en/wiki/Schlenk_flask

 

This same theme popped up on blacklight too today.

There, I suggested a few ideas.

Namely the use of lithium nitride as a base, apparently its a fucking strong ass superbase, moisture sensitive, but it isn't pyrophoric, or perhaps one of the more basic alkoxides in a polar aprotic solvent, wherein they become much more strongly basic.

IIRC which I may not, these reaction involves deprotonation using an extremely strong base simular to how Safrole isomerization works just in these cases the reaction is setup so that the amine is the lest energetic and most stable of the structures where as in isomerization the electron shifts inorder to stabilize itself.

Sorry for such a hackish answer but many here could fill in the blanks, half truths and total lies of the above statement.


I have a book on superbase chemistry but with my FTP down I can not link to it and I can not upload it because it is to large for the site here to handle. Still do a search on this site for the Dimsyl ion to see what a real powerful base is all about. I theorize that could make hydroamination simple oneday by someone dedicated enough to experiment instead of monkey cook see, monkey cook do.....